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Type 2 diabetes (T2D) is a chronic metabolic condition characterized by insulin resistance and pancreatic ß-cell failure. Over the past decade, the incidence of T2D has been increasing, and is of growing concern, as T2D is often associated with obesity. Excess iron has been shown to induce ferroptotic pancreatic cell damaged caused by oxidative stress due to increased production of reactive oxygen species (ROS). This facilitates the progressive impairment of ß-cell function in the pathogenesis of T2D. The present thesis presents two novel therapeutic strategies for iron related damage in T2D management; the first approach sought to attenuate oxidative stress with different polyphenols and the second is an inducing antioxidant pathway by polyphenols against excess iron. Studies were conducted to gather evidence on the protective functions of various polyphenols in both in vitro cell and in vivo mouse models. This research presents data on the protective effect of curcumin and (-)- epigallocatechin-3-gallate (EGCG), against iron loading and erastin-mediated ferroptosis in MIN6 cells. Curcumin and EGCG both significantly protected pancreatic cells against iron-induced oxidative damage and erastin-induced ferroptosis. The polyphenols enhanced cell viability in erastintreated MIN6 cells in a dose- and time-dependent manner. Furthermore, MIN6 cells exposed to erastin alone showed elevated levels of iron, glutathione (GSH) depletion, glutathione peroxidase 4 (GPX4) degradation and lipid peroxidation compared to cells that were protected by co-treatment with curcumin or EGCG. Taken together, the data identify curcumin and EGCG as novel ferroptosis inhibitors, which might exert their protective effects by acting as iron chelators and preventing GSH depletion, GPX4 inactivation, and lipid peroxidation in MIN6 cells. The implications of the findings on the effects of iron overload and ferroptosis represent a potential therapeutic strategy against ironrelated diseases. Antioxidant therapy is a promising therapeutic strategy to prevent or even reverse the progression of iron-induced oxidative stress and ferroptosis by activating nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Thus, phenolic acids, ferulic acid (FA) and, its metabolite Ferulic Acid 4-O-Sulfate Disodium Salt (FAS) were evaluated against oxidative stress and ferroptosis in both in vitro cell and in vivo mouse models. FA and FAS both significantly protected MIN6 and HepG2 cells against erastininduced ferroptosis and iron related oxidative stress. Phenolic acids corrected oxidative stress markers in iron overloaded mice models. The prospects of those phenolic acids to reduce oxidative stress and ferroptotic cell damage will be of immense benefit in improving patient outcomes.

Mycoprotein is a sustainably-produced, fungal-derived dietary protein source and its consumption has been shown to improve acute postprandial glycaemic responses and decrease circulating cholesterol concentrations. However, whether these findings translate to habitual mycoprotein consumption improving physiologically relevant, longer-term changes in insulin sensitivity (IS) and/or glycaemic control has not yet been investigated. Mycoprotein is naturally rich in RNA-derived nucleotides (~10 g per 100 g dry weight), but heat-treated during production to reduce RNA content (to under 2 g per 100 g dry weight), for commercial products to comply with FAO/WHO/UNICEF recommendations limiting the additional dietary nucleic acid load from single-cell protein-rich novel foods to 2 g/day. These recommendations are based on data showing that short term ingestion of high-dose (> 2 g/day) isolated (or yeast-derived) nucleotides results in elevations in circulating uric acid concentrations above clinically acceptable levels (i.e. of > 420 µmol.L-1). Epidemiological and observational studies have reported that serum uric acid concentrations positively correlate with the development of gout, hypertension and metabolic syndrome, and are a predictor of type 2 diabetes, though causal links remain to be established. Despite these concerns regarding dietary nucleotides, serum uric acid concentrations and metabolic health, evidence supports an increased dietary requirement for nucleotides during periods of rapid growth (e.g. infancy) and stress, such as in certain disease states. Muscular exercise is one of the most common states of physiological stress and emerging data imply beneficial effects of dietary nucleotide supplementation on exercise performance and recovery. Dietary nucleotide supplementation has been shown to reduce post-exercise stress hormone response, improve markers of immune health, and result in improvements to muscular strength, force production and time to exhaustion. It has been suggested that dietary nucleotides might positively affect energy production but studies have not yet examined this. Increased production of ATP modulated by dietary nucleotide intake prior to submaximal moderate-intensity exercise might lead to improved exercise performance, potentially by sparing muscle glycogen. Additionally, these potential benefits to energy production might also lead to improved recovery following glycogen depleting exercise. Ribose, a pentose monosaccharide that makes up the structure of nucleotides, has also been proposed as a limiting factor in the production of ATP. As such, dietary ribose (like dietary nucleotide) intake might modulate fuel utilisation and improve energy production and exercise performance in a depleted state, as well as assist skeletal muscle cells in recovery from fatigue; but further research to establish these effects is necessary. The studies described in this thesis, performed in healthy human volunteers, have focused on two main topics. Firstly, the impact of both mycoprotein and dietary nucleotide intake on markers of metabolic health was assessed. Secondly, the potential for dietary nucleotides and ribose to impact muscle ATP and glycogen concentrations and endurance exercise muscle metabolism, performance and recovery. The major findings were that substituting meat/fish for mycoprotein twice daily for 1 week did not modulate whole-body IS or glycaemic control but resulted in changes to plasma lipid composition, the latter primarily consisting of a coordinated reduction in circulating cholesterol-containing lipoproteins. The ingestion of a nucleotide-rich mixed meal was found to increase serum uric acid concentrations for ~12 h but did not influence postprandial blood glucose or serum insulin concentrations. Accordingly, twice-daily consumption of high-nucleotide mycoprotein for one week led to sustained increases in serum uric acid concentrations (above clinically relevant thresholds), but not to any associated deleterious effects in IS, glycaemic control or plasma lipid composition. Finally, the twice-daily ingestion, for 2 weeks, of a nucleotide-rich mycoprotein drink, with or without added ribose, did not influence skeletal muscle ATP content, muscle fuel utilisation during exercise, exercise performance or the metabolic or performance-related recovery from exercise. The present thesis documents the first investigations into the potential impact of mycoprotein on IS and extends on previous observations of the beneficial effects of mycoprotein intake on blood lipid profile by demonstrating how rapidly these benefits ensue. Further novel findings were that high nucleotide intake, even when incorporated into mixed meals, leads to a cumulative increase in serum uric acid concentrations, which after three to five days become clinically significant. Despite this, our results clearly show measures of IS and glycaemic control remained unaffected. Furthermore, it is described in this thesis the first attempt to increase resting skeletal muscle ATP concentrations in humans using dietary nucleotide and ribose supplementation and to assess their impact in muscle fuel utilisation during fatiguing exercise and after acute recovery. The findings of this thesis have theoretical and practical applications regarding the use of sustainable alternative protein sources on the prevention and treatment of cardiometabolic risk factors and add valuable knowledge to our understanding of the role of dietary nucleotides and ribose in muscle fuel utilisation and exercise performance.

Food and beverages containing large amounts of highly bioaccessible starch and sugars induce pronounced postprandial blood glucose concentrations. Chronic exposure to exaggerated sharp peaks in blood glucose can lead to adverse modifications to functional proteins, oxidative stress and pancreatic ß-cell dysfunction, thereby increasing the risk of cardiometabolic diseases. Previous research by our group demonstrated that 1.8 g of polyphenol-rich apple attenuated the early-postprandial glucose response to a high-carbohydrate meal. Lower effective doses of apple polyphenols on postprandial glycaemia are unknown and mechanisms of action to explain the glucoregulatory properties of apple polyphenols have not been fully elucidated. The overarching aim of this thesis is to present evidence to support the acute gluco-modulatory mechanisms of a polyphenol-rich apple extract (AE). This has been carried out in three phases: 1). A randomised controlled trial (RCT) in healthy volunteers to demonstrate clinical efficacy and determine potential physiological mechanisms of the AE; 2). A systematic review of in vitro studies investigating the effect of polyphenol-rich fruit extracts on the activity of carbohydrate-hydrolysing enzymes. 3). In vitro experiments to investigate mechanisms relating to intestinal transport and digestive enzyme inhibition. The RCT tests the hypothesis that drinks containing the AE (HIGH=1.8 g AE; MED=1.35 g AE; LOW=0.9 g AE) will dose-dependently decrease the rate of glucose absorption v control, assessed by measuring early-phase postprandial glucose concentrations (incremental area under the curve (iAUC) 0-30 min) as the primary outcome, following a 75 g starch+sucrose meal in healthy adults (n=30). Secondary outcomes include: additional glycaemic markers in addition to postprandial parameters of insulin secretion (insulin, C-peptide), glucose-dependent insulinotropic polypeptide (GIP) and serum polyphenol metabolites; gastric emptying rates measured by the acetaminophen absorption test; and 24 h urinary glucose excretion as an indicator of polyphenol-induced inhibition of renal glucose reabsorption. All AE drinks dose-dependently reduced plasma glucose iAUC 0-30 min relative to control; the HIGH dose inhibited by 58 % compared to control. Similar significant dose-dependent effects were observed for insulin, C-peptide and GIP, and serum phloretin, quercetin and epicatechin metabolites were detected postprandially. Gastric emptying rates and urinary glucose excretion did not differ. The systematic review included 34 papers using in vitro digestion models to quantify gut digestive enzyme(s) activity on starch digestion in the presence of fruit polyphenol extracts. Studies were consistent overall in showing stronger inhibition of α-amylase compared to α-glucosidase by proanthocyanidin- and/or ellagitannin-rich fruit extracts. However, greater consistency between in vitro assay conditions is required for future research in this area to enable meaningful synthesis of the literature as a whole. The original in vitro experiments reported in this thesis verified the inhibitory effects of the same AE used in the RCT and various fractions of the extract on intestinal glucose transport (IC50=1.19 ± 0.35 mg/mL) and α-amylase activity (Ki=0.28 ± 0.06 mg/mL); using Caco-2/TC7 cells as a model of the human enterocyte and fluorescence digestion assays with porcine pancreatic α-amylase, respectively. A dose of 1.12 mg/mL AE - approximately equivalent to the HIGH dose consumed by volunteers in the RCT - inhibited α-amylase activity by 83 % and total glucose uptake by 48 %, relative to control. Of the apple extract fractions, the fraction high in phlorizin and procyanidin B2 was the most effective at inhibiting α-amylase activity (Ki=0.56 ± 0.36 mg/mL), whilst the fraction high in phlorizin and quercetin was the most potent inhibitor of total glucose uptake (IC50=0.27 ± 0.04 mg/mL). Combined results from the systematic review and in vitro work highlighted the need to identify other secondary metabolites in apples that may have biological-activity potential. This research has demonstrated that the AE, even at a low dose, can delay early-phase glycemia. Both the inhibition of α-amylase and glucose uptake are likely two important mechanisms which can explain the glucoregulatory properties of the AE. We have highlighted several major gaps in our understanding of high-polyphenol fruit extracts and the 'unknown' components that may be present. It is important that future research identifies the potential combination of the effects derived from the complex mixture of phytochemicals that are likely in the AE, in addition to polyphenols. Such knowledge could allow effective choices to be made for development of the AE as a functional ingredient in novel functional foods and/or beverages.

Background: It is well recognised that eating a poor quality diet can lead to a number of long term health conditions and premature mortality. In response, a variety of materials, offering healthy eating advice from both state and commercial sources, have been produced in the UK to help and encourage people to eat well and avoid diet related health issues. However, a large proportion of the population still suffer from long term conditions which could have been avoided through an improved diet. The aim of this research was to consider how healthy eating advice is relayed to the public and how people relate to it by exploring how healthy eating is socially constructed in the 21st century in the East of England. The research aimed to uncover the discourses used in healthy eating texts in the UK, how people positioned themselves in relation to these discourses and the power relations between institutions and the UK public. Method: A Foucauldian Discourse Analysis was applied to a range of healthy eating texts from both state and commercial sources. In addition, five focus groups were carried out to determine how the participants positioned themselves within the text's discourses and their sense of trust in the materials. Findings: The analysis of the texts uncovered a combination of discourses including scientific, thermodynamic, natural, childcare, medical and moral discourses which offered up subject positions to their readers in relation to moral citizenship and personal responsibility. Through the use of bio-power, foods within the texts appeared to be categorised as 'good' or 'bad' foods in which bad foods were considered to be risky to health due to their nutritional composition. Most of the texts assumed people have the agency to follow the text's advice and failed to consider the readers' personal context. Focus group findings revealed that many participants felt that healthy eating should be based on common sense and ideally it is better to listen to your body to understand what it needs and there is no one size fits all approach such as that presented in the texts.

Obesity is now described as a pandemic (Hu, 2013) and a strong association has been identified between sugar consumption and excessive weight gain (e.g. Te Morenga, Mallard & Mann, 2013). Yet difficulty in establishing the factors driving this relationship leaves a dearth of research investigating causal mechanisms behind this global crisis (Lean, Astrup & Roberts, 2018). Food choice has been linked with cognitive processes involved in decision making (Peters, 2009), which in turn, has been linked with affect, i.e. mood and emotion (Lerner, Li, Valdesolo & Kassam, 2015). The aim of this thesis was therefore to explore the way in which both state and trait affect influence impulsive, sweet food decision making across three studies. As hypothesised and supported by affective regulation theory (Gross, 1998), results showed that as laboratory-induced mood (i.e. state affect) moved from positive to negative, the likelihood of choosing a chocolate reward over a non-food/neutral reward increased. This finding was conclusively evident when controlling for other factors such as chocolate craving in Study 2, ultimately highlighting the complex influence of affect on sweet food choice. Following this initial choice in Studies 1 and 2, subsequent hypotheses concerning impulse and self-control were not wholly supported as participants in both mood conditions were more likely to make impulsive decisions than exercise self-control. While affective regulation theory also explained those in negative moods making impulsive choices, an integrative framework was put forward to explain those in positive moods displaying the same behaviour (Andrade, 2005). In Studies 2 and 3 a willingness-to-pay (WTP) task was included to explore the relationship between state and trait affect and economic decisions concerning chocolate and high-sugar foods. While laboratory-induced mood did not predict WTP prices in Study 2, decreasing positive affectivity (i.e. trait affect) was found to significantly predict higher WTP prices for chocolate and high-sugar items, as hypothesised in Study 3. Reduced positive affectivity has been linked with symptoms of depression (Watson, Clark & Carey, 1988) which, in turn, is associated with an increase in desire for chocolate and sweet foods (Lester & Bernard, 1991). These results therefore provided robust evidence that higher spending for sweet items is connected to the absence of positive affectivity rather than presence of negative affectivity. Finally, increasing chocolate craving was found to significantly predict choices and increasing WTP prices for chocolate items in Studies 2 and 3. The potential parallel between chocolate and substances more commonly associated with addiction is discussed, together with the broad, practical implications of all findings in the context of sweet food choice and obesity.

Background: The intake of nutrient-dense foods is recommended for overall health improvement and maintaining healthy body fat. However, there is a dearth of evidence on the relationship between the dietary nutrient density and body fat percentage. Investigating this relationship depends on the availability of valid dietary assessment methods for estimating micronutrients and the bioavailability of micronutrients, considering that nutrient-dense foods are rich in phytate which may affect the bioavailability of micronutrients. Aims: This thesis primarily investigated the association between change in dietary nutrient density and change in body fat percentage using a prospective cohort study design. It also validated a 4-day food photography method for estimating micronutrients in the diet and conducted a systematic review on the influence of dietary phytates on the bioavailability of micronutrients. Methods: This research was conducted in three stages. Firstly, a 4-day food photography method was validated against the weighed food record method as a reference. Secondly, a systematic review was conducted on the influence of dietary phytate on the bioavailability of micronutrients. Finally, the association between change in dietary nutrient density and change in body fat was investigated in a 6-month prospective cohort study involving 108 adults. For the validation study, measures obtained from both methods were compared using Student's t-test, and the agreement between both measures was assessed using Bland-Altman analysis. In the systematic review, specific databases were searched, and the results were reported based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Statement. The relationship between dietary nutrient density and body fat percentage was investigated using linear mixed model regression. For all stages, the statistical significance was considered for p-values less than 0.05. Results: In the validation study, the difference between the measures obtained by the food photography method and the weighed food record was not statistically significant (p > 0.05). Bland-Altman plots showed a good agreement for the nutrient estimates obtained by both methods. The bias for each nutrient estimate was less than 20%. The systematic review concluded that phytate negatively influenced the bioavailability of iron, magnesium and, zinc. In the cohort study, an increase in the dietary nutrient density of vitamins A, E, K and C, folate, iron, calcium, magnesium, potassium, selenium, zinc and, phosphorus were each found to correspond to a decrease in body fat percentage (p < 0.05) after adjusting for dietary phytate and covariates. Conclusions: The food photography method is suitable for assessing dietary micronutrients; dietary phytate reduces the bioavailability of iron, magnesium and, zinc; an increase in dietary nutrient density of vitamins A, C, E and K, folate, iron, calcium, magnesium, selenium and phosphorus was associated with a decrease in body fat percentage in adults.

This research thesis further contributes to the understanding of both psychological influences on dietary choices and bodyweight status, and the impacts of diet interventions on psychological wellbeing. This thesis is split across three chapters, each outlined below: Chapter One A systematic review of the impacts of Mediterranean diet interventions on psychological wellbeing. Narrative synthesis within indicated that Mediterranean diet interventions may lead to a range of improvements in psychological wellbeing across clinical and non-clinical populations. Particular benefits on hedonic and eudaimonic psychological wellbeing are discussed. Clinical implications and future research directions are outlined. Chapter Two A research study examining the influence of implicit (relative to explicit) attitudes toward 'junk food', on habitual consumption of junk food and subsequent risk of overweight/obesity. Results suggested that implicit attitudes are significant and more powerful predictors of habitual consumption of junk food than explicit attitudes, and might influence risk of overweight/obesity. It is concluded that related interventions to improve public health may benefit from targeting implicit attitudes potentially influencing eating behaviours and habits. Chapter Three A personal reflective account of the process of conducting the research outlined in chapter one and two. A 'pragmatist reflective position' is broadly taken in order to aid learning from the research experiences. Following reflection across a range of topics within, numerous benefits to the role of clinical psychologist are highlighted and discussed.

Background: Dementia is one of the world's biggest health problems and is a major public health challenge that is becoming more common as the aged population grows. There is no known cure for dementia, and thus more efforts have been made to investigate its risk or protective factors for prevention. Previous studies suggested that increased consumption of fish reduces the risk of cardiovascular diseases. However, it is unclear whether the consumption of fish was associated with the risk of dementia and outcomes of people with dementia. Also, few studies have specifically examined factors influencing the consumption of fish in older people, despite the world population aging. The purpose of this research project was to conduct a systematic literature review and examine the determinants and impacts of fish consumption on the incidence and mortality of dementia in older people using a convergent parallel database mixed methodological approach. Methods: This study employed a systematic literature review and a mixed method of quantitative and qualitative approaches that is based on a large cohort study dataset from China and two focus group discussions from the United Kingdom. In 2007-2009, 6071 participants aged ≥60 years were randomly selected from urban and rural communities in five-provinces, China. Using a standard interview method, participants' socio-economic status, disease risk factors and fish consumption over the past two years were documented at baseline and this was followed up until 2012. The data of the cohort were analysed in multivariate adjusted logistic regression and Cox proportional hazards regression models. In 2018, the focus group discussions that consisted of 12 older adults were conducted in the UK, and the qualitative data was analysed using thematic analysis. Results: The findings of these studies demonstrated that increased consumption of fish was associated with reduced risk of dementia and all-cause mortality among older people. The study also examined and found that large socioeconomic inequalities, and certain lifestyle, psychosocial factors and health-related conditions are significant determinants of fish consumption. The qualitative study further revealed that participants consume fish for its taste, flavour, the desire for variety of food and the nutritional and health benefit including reducing the risk of dementia and other health outcomes. Although cost, bony/scaly fish, smell and availability/accessibility of fish were highlighted as the major barriers of fish consumption. Conclusions: This research has provided evidence for preventing dementia and reducing all-cause mortality through adequate fish consumption. The findings of the study should be extended to improve public health policy, and this could form the basis for further research.

Dietary assessment surveys are an important tool for measuring and/or monitoring the nutritional profile of a population. The analysis of data that is collected in these surveys helps to develop health care guidelines and policies that minimise the risk of diet related diseases on a national scale. For years these surveys had to be conducted in a form of an interview by trained researchers with a nutritional background. The emergence of systems that automate interviewer-led protocols and transform these interviews into online surveys has addressed financial limitations and brought scalability into dietary assessment studies. In the meantime, online dietary assessment surveys mostly copy the interviewer-led procedures and inherit some of their methodological issues that lead to misreporting of dietary intake and lower the accuracy of assessment. This thesis primarily focuses on the issues related to human-memory, motivation of respondents to take part in dietary assessment studies, and the usability of survey interfaces. This work pinpoints the elements of automated dietary assessment systems, where these issues affect the accuracy of results. This analysis is then translated into three research questions of this thesis. Challenges related to human-memory are then addressed by developing and evaluating a recommender system for prompting omitted foods in online dietary assessment surveys. This work also explores short retention intervals (i.e. time between an intake and recall) as another method for recall assistance. As a way to motivate respondents to take part in dietary assessment surveys this thesis explores tailored dietary feedback provided to respondents at the end of a survey. Usability and performance of new methods are analysed in real-life dietary assessment surveys using a usability framework developed for this research. Acceptance of the methods is analysed using thematic analysis of transcribed interviews with respondents. Research activities conducted during this work provide some support to hypotheses defined in the research questions.

Rationale: The proportion of adults aged above 60 is rapidly increasing and by 2050 they will comprise almost one fourth of total world population. However, with moderate disability rates also increasing, there is great need for older people to maintain overall well-functioning. Physical and cognitive functioning play a major role in daily activities and determine life quality of older people. Maintaining walking ability is crucial for independent living and walking speed is predictive of overall health, survival and better physical and cognitive functioning. Rates of functional decline vary interindividual and between sexes, with women living longer but with higher comorbidity rates than men. Part of this variability in functional trajectories is attributable to modifiable lifestyle factors, with diet being of great interest. Specific nutrients and presumably healthy diets have been associated with better physical and cognitive performance in older people. Research gap: Evidence for diet quality in line with current dietary guidelines and objective measures of well-functioning, important for older people, is limited. In addition, considering well-known differences in eating and ageing trajectories between men and women, it is highly underexplored whether the effect of diet on overall functioning of older people is sex-specific. Finally, evidence for whether accumulation of healthy dietary exposure over time may exert additional benefits on overall functioning in later life, is scarce. Aim: To investigate the overall and sex-specific prospective associations between diet quality in late midlife and over a 27-year period in adulthood and objective measures of walking speed in older life, indicating survival and physical and cognitive functioning. Methods: This thesis used dietary data (five-day food diaries) of men and women from four time points of the 1946 MRC National Survey of Health and Development birth cohort (N=5,362) when participants were at ages 36, 43, 53 and 60-64 and measures of walking speed from the Insight 46 (N=502), its clinical sub-study, when participants were at age 69- IV 71. Diet quality was defined by the Healthy Eating Index-2015 at each age (low: 0 - high: 100). Prospective associations with walking speed at age 69-71 were assessed for diet quality (a) in late midlife (age 60-64) and (b) over adulthood (from age 36 to 64), considering major demographic, health and lifestyle factors from age 36 to 64. Sample size: At least one valid dietary assessment was available for n=480. Walking speed was available for n=474 and among men (51%) and women in the Insight 46, dietary data was available as follows: n=313 (age 36), n=369 (age 43), n=346 (age 53), n=444 (age 60-64). Final sample size ranged from n=331 (Chapter 4) to n=437 (Chapter 6). Results: Diet quality improved over adulthood (age 36: HEI=47 ± 11 vs age 64: HEI=62 ± 13). Women had higher diet quality than men at each age (β=4 HEI points, 95% CI: 3, 6; p<0.05). Men had faster absolute values of walking speed than women at age 69-71 (1.39 m/s ± 0.15 vs 1.32 m/s ± 0.14, p<0.05), which was attenuated after controlling for anthropometric differences (p= 0.85). Main analysis showed there was a null overall association between diet quality in late midlife (β: 0.01 m/s, 95% CI: -0.01, 0.02) and over adulthood (β: 0.02 m/s, 95% CI: -0.02, 0.03) and walking speed in later life. Sex-specific analysis showed a positive association between diet quality in late midlife and faster walking speed in women independently of other factors (β: 0.02 m/s, 95% CI: 0.01, 0.04), but null associations for men (β: -0.01 m/s, 95% CI: -0.03, 0.01). When walking and performing a cognitive task, there was indication of a positive association between diet quality and walking speed in women (β: 0.03 m/s, 95% CI: 0.01, 0.05) and an inverse association in men (β: -0.02 m/s, 95% CI: -0.05,-0.01). Finally, starting with and maintaining high diet quality over adulthood was associated with faster walking speed in later life in women (β: 0.04 - 0.06 m/s, 95% CI: 0.01, 0.11), thus reflecting better functioning and longer survival, but not men (β: -0.01 m/s, 95% CI: -0.02, 0.01); yet the association was not independent of other lifestyle factors. V Contribution to knowledge: This thesis provided novel insights of the impact of diet quality across various stages over adulthood on measures of overall functioning, which predict survival and are clinically relevant for older people. Furthermore, it added original evidence for sex differences modifying this relationship and most importantly it suggested that achieving and maintaining high diet quality the longest possible over adulthood is likely to yield additional benefits towards better age-related physical functioning, in particular in women.

Producing meat generally leads to greater greenhouse gas emissions, deforestation, water use and pollution, and biodiversity loss compared to producing plant-based foods. While there are many supply-side measures that can help to mitigate livestock's environmental impact, substantively reducing meat consumption is required to ensure that food systems can sustainably feed the growing global population and would result in some benefits for human health too. Behavioural interventions to encourage changes in eating habits could help to reduce meat intake, but few such interventions have been implemented and rigorously tested. The aim of this thesis is to contribute towards addressing this evidence gap by generating empirical evidence on the effectiveness of behavioural interventions to reduce meat consumption through (i) systematically reviewing and synthesising the evidence on the effectiveness of interventions targeting conscious behavioural determinants or restructuring physical micro-environments; (ii) the development of a novel behavioural intervention (Replacing Meat with Alternative Plant-based Products, RE-MAP) to reduce meat consumption through the provision of meat substitutes, infographics, success stories, and recipes; (iii) a randomised trial evaluating the impact of RE-MAP on meat consumption, wider dietary changes, markers of health risk, markers of environmental degradation, and psychosocial factors related to meat and meat substitutes consumption; and (iv) qualitative interviews exploring the mechanisms through which the intervention might have delivered impact and recipients' experiences of the intervention. The results of my DPhil suggest that some behavioural interventions targeting conscious determinants of human behaviour and restructuring physical micro-environments can help to reduce meat consumption. Providing meat substitutes for four consecutive weeks along with supporting informational material is an acceptable strategy to help people eat less meat and emerged as one of the most effective interventions to reduce meat consumption tested to date. Specifically, RE-MAP led to a 63 g/d reduction in meat consumption at the end of the intervention and a 39 g/d reduction four weeks after the intervention completion. Based on these findings, future research should investigate how to translate the active components of the RE-MAP intervention into a scalable policy option.

The dietary supply of copper (Cu) as an essential trace element has implications for dairy cow performance, health and fertility. Despite being the most widely reported mineral deficiency, there is evidence to suggest an over-supplementation of the element on farm, consequently 38% of Holstein-Friesian cull cow liver that enters the food chain contains toxic liver Cu concentrations. Suggested reasons for this over-supplementation include suppressing the effects of the Cu absorption antagonists sulfur and molybdenum, and a perception from those within the industry that in the absence of clinical toxicity, there are no harmful sub-clinical consequences of elevated hepatic Cu concentrations. Recent evidence however of an increasing Cu status in lactating Holstein-Friesian cows as a result of replacing grass silage with maize silage in the diet, advocates the potential of other nutritional factors to alter Cu absorption. The objective of these studies was to determine dietary factors other than concentrations of Cu antagonists that may have increased hepatic Cu concentration on farm, and determine the long-term consequences of Cu over-supplementation on Holstein-Friesian heifer performance, health, and fertility. Results in study one identify the potential of increased dietary starch concentration and/or decreased ruminal pH to increase the Cu status of lactating Holstein-Friesian cows, and may indicate a lack of understanding within the industry regarding Cu availability in total mixed rations. Despite a marginal growth rate increase in study two, feeding Holstein Friesian heifers Cu in excess of requirement during the growing phase decreased fertility, modulated the immune response, and compromised early lactation performance when continued beyond parturition in study three. In conclusion, increasing dietary starch concentration and/or reducing rumen pH increases hepatic Cu reserves, and the long-term feeding of Cu above requirement during the rearing phase and early lactation may compromise growing heifer fertility, as well as lactation performance.

Introduction - Adherence to the Mediterranean diet, could reduce the risk of mortality and CVD across the life course. However, its epidemiological instrumentation needs to be contextualized and adapted to local cultures. Moreover, there is evidence that typical dairy products should be disaggregated in the MDS due to divergent health properties. Methods - The Västerbotten Intervention Program (VIP), the Northern Sweden MONICA, the H70 elderly study, the Copenhagen MONICA study, and the IDEFICS EU children study were included. A refined version of the Mediterranean Diet Score (MDS) was calculated from diet histories (H70), FFQs (VIP), and food records (MONICA-Copenhagen) by including foods that better describe the context of a genuine Mediterranean diet (e.g., wholegrain instead of total cereals) and ingredients from mixed dishes. Cox models, adjusted for potential confounders, were used to compare the original and refined MDS and their associations with mortality, CVD incidence, and mortality. Adjusted Cox models were also used to test the association between dairy intakes and the risk of mortality in the VIP and H70 cohorts. Adherence among children was assessed using both FFQ and recall data, and its association with BMI, waist circumference, WtHR, and % fat mass was assessed crosssectionally and longitudinally. Results - The refined MDS, but not the original score, inversely predicted the risk of allcause mortality in the MONICA-Copenhagen (HR = 0.93) and VIP (HR = 0.95) studies, as well as with CVD incidence and CVD mortality in all cohort studies. Stroke incidence and stroke mortality were not associated with both scores. Milk intakes directly predicted all-cause mortality (HR = 1.02, 95% CI: 1.00, 1.05) whereas cheese intakes showed an inverse association with all-cause mortality (HR = 0.94, 95% CI: 0.91, 0.97). Fermented milk intakes showed a borderline significant inverse association with all-cause mortality. The MDS was inversely associated with the risk of overweight and obesity in children with low prevalence of high-adherent children in all countries (< 30%) except Sweden. Discussion and conclusions - The adoption of a Mediterranean-like diet is protective for CVD across the lifespan, and adherence should be increased among children. The sensitivity of assessments evaluating adherence to this pattern can be increased. The results on dairy product intakes suggest differences between milk and cheese, but they should be interpreted cautiously.

Orthorexia Nervosa (ON) describes a pathological, unhealthy fixation with eating healthy food. Research concerning the symptomatology of ON, and its prevalence in numerous samples, differs as there no official measures or clear diagnostic criteria exist for this fairly new affliction. Though research on the link between the epidemiology of ON and social media is gaining traction, published evidence is scarce. This study intends to further understand ON and its possible link to the use of social media, and specifically, to test the prevalence of ON in an opportunity sample with the use of two ON measures - the ORTO-15 and the Tereul Orthorexia Scale (TOS); to use and validate a new ON measure (TOS); to examine the relationship between ON and social media use, with a focus on Instagram users; and to further understand the participants' interpretations of the possible link between eating patterns and social media use. This study uses a convergent design and a mixed methods approach, which employs both statistical and thematic analysis (TA) to evaluate the quantitative and qualitative data generated. Data from 201 participants suggested a high prevalence of ON across the sample, and the results also reinforced the validity of the TOS measure (α = .86). ORTO 15 scores showed significant differences between age groups, genders, and Instagram users and non-Instagram users. The TA generated three overall themes: 'The Importance of Belonging', 'Health as Art' and 'Craving'. The high prevalence in the sample may have been a result of the researcher's recruitment method, and the ON measures may have categorised individuals on non-medically prescribed diets as 'orthorexic'. Both the quantitative and qualitative results offer evidence to support a possible link between ON and social media use, specifically Instagram. Further research should be done to establish official criteria and measures for ON and the effect of social media on eating patterns, and to investigate the notion of 'healthism'.

Background: Decades of research have demonstrated that dietary-induced weight losses are rarely maintained in the long-term. The research described in this thesis aimed to contribute towards answering one big question - why is long-term weight loss maintenance (WLM) difficult to achieve for most people? A range of factors were examined including psychological, physiological and clinical/demographic influences. Aims: This thesis had four overarching aims: 1) To gain an in-depth understanding of weight loss and WLM experiences (study 1) 2) To integrate physiological and psychological perspectives to reach a broad view of WLM difficulties (study 2) 3) To investigate the role of appetite-related hormones in weight regain (study 3) 4) To investigate clinical and demographic predictors of type 2 diabetes remission and the role of weight loss (study 4) Methods: The four empirical chapters in this thesis are based on two distinct studies (‘Beyond’ and ‘DiRECT’). In both studies, individuals were recruited into a 2-year multi-component behavioural weight management programme. Weight loss was initiated by total diet replacement, which provided 825-853 kcal/day of liquid formula diet (shakes/soups) for up to 20 weeks, followed by ongoing visits designed to support long term WLM until 2-years. Both studies demonstrated average weight losses in the region of 15kg after total diet replacement, followed by varying degrees of weight regain over time. These studies therefore provide a suitable context to study the challenges of WLM. In study 1, a longitudinal qualitative design was used to investigate weight loss and WLM experiences around theoretical themes known to be important for behaviour change maintenance: motivation, self-regulation, habits, psychological resources and social/environmental influences. In study 2, a mixed-methods study design was used to evaluate the role of physiological and psychological factors in weight regain. The role of appetite-related hormones (GLP-1, ghrelin, PYY, leptin and GDF-15) and adaptive thermogenesis in weight regain were the specific focus. Resting metabolic rate was measured by indirect calorimetry and body composition was assessed by whole-body MRI. Findings were integrated alongside qualitative interview data from study 1. Studies 3 and 4 were post hoc analyses of the DiRECT study, investigating potential predictors of diabetes remission, weight loss and weight regain using multiple regression analyses. The role of appetite-related hormones (leptin, ghrelin, GLP-1 and PYY) was examined in study 3 and demographic and clinical influences were the focus of study 4. Results: In study 1, 64 interviews were completed over a 2-year period in 11 participants (median, n=6 per participant, range:4-8). Weight management experiences were individualised and the behavioural maintenance model used to anchor the analysis offered a fitting and broad framework to capture experiences. All theoretical themes (motives, self-regulation, habit, psychological resources and social/environmental influences) contributed towards understanding weight-related cognitions, behaviours and outcomes. Similarities and differences between Maintainers and Regainers were described and there was no single, common factor that seemed decisive in determining outcomes. Negative views of obesity were strong motivations for weight loss and WLM. Perceiving new routines as sustainable and developing a ‘maintenance mindset’ was characteristic of Maintainers whereas meeting emotional needs at the expense of WLM goals during periods of stress and negative mood states was reported more often by Regainers. Optimistic beliefs about maintaining weight losses seemed to interfere with barrier identification and coping planning for both Maintainers and Regainers. Better long-term outcomes tended to be achieved by those with larger initial weight losses, which was linked to greater satisfaction and changes in self-perception In study 2, qualitative data from study 1 was integrated within a mixed-methods study design to present an analysis investigating the role of physiological and psychological factors in weight regain. Fasting GLP-1 concentration measured before and at maximal weight loss was negatively associated with weight regain. Adaptive reductions in thermogenesis were observed but did not associate with weight regain. Despite significant increases in ghrelin and reductions in GLP-1 and leptin these changes did not correspond to increases in subjective hunger, and on the contrary, participants often reported having a smaller appetite after weight loss during qualitative interviews. Individuals tended to perceive lapses and weight regain through the prism of stress and negative emotions. In study 3. the findings concerning GLP-1 from the study described above were investigated further, but not replicated, in a large cluster-randomised trial. However, the rise in fasting ghrelin (but not any other measured hormone) during weight loss between baseline and 12-months was a predictor of weight regain between 12 and 24 months. Concentration of ghrelin at 12-months also predicted subsequent weight regain, and ghrelin remained elevated over time despite weight-regain, which may suggest a compensatory drive to regain weight. This study provides further evidence to the hypothesis that physiological adaptations contribute to weight regain following diet-induced weight loss. In study 4, weight loss was found to be the best predictor of type 2 diabetes remission. This raised questions regarding predictors of weight loss, and WLM. Men were more successful at sustaining remission and weight losses over time. Higher anxiety/depression scores and antidepressant drug use were associated with poorer weight losses and remission outcomes. More frequent attendance predicted weight loss and remission. Weight loss achieved in the early weeks of treatment (by 4 weeks) was associated with remission status at 12 and 24-months, confirming evidence from other studies that those losing weight more rapidly achieve better long-term WLM outcomes. These findings provide evidence to clinicians, healthcare planners and to patients that diabetes remission is possible if adequate weight loss is achieved. Conclusions: Weight regain is a complex problem and improving outcomes requires a multi-faceted approach. By integrating methodologies within the same study populations a broad understanding of WLM and its difficulties was reached. To lose and maintain weight losses in the long-term requires a combination of motivation, support, self-regulation and an investment of time and energy to adhere to healthy lifestyle behaviours. Findings from this thesis suggest that adherence to a reduced energy diet supporting WLM would be enhanced through intervention strategies addressing negative emotional states (e.g. from life stress, low mood/depression) and attenuating the rise in the hunger hormone ghrelin, which occurs in response to significant diet-induced weight loss and is likely to increase the drive to eat.

The convergence of a changing burden towards increased rates of diet-related non-communicable diseases (NCDs) and of growing rates of urbanisation—considered a key upstream factor in shiftingdiets towards patterns conducive to NCDs—has drawn attention to low and middle-income countries (LMICs) as the epicentre of current global public health challenges. Using the case of Indonesia, a country that has undergone major shifts in terms of socio-economic and health indicators over the past decades, this thesis problematises the assumed linearity of food systems and dietary change in LMICs, and the role of urbanisation in these processes. It examines whether there is evidence of an alternative narrative of change, which can account for the heterogeneity existing in food systems and cultures between and within LMICs and in their urban food environments. The first part of the thesis studies the relationship between urbanisation and diets through the analysis of large-scale quantitative longitudinal data available for Indonesia. Findings from this portion of the thesis suggest that some components of the traditional diet are resilient to the socio-economic shifts associated with increased urbanisation; and that varying urbanisation levels at more localised scales have different effects on diets. In the second part of the thesis, these findings are triangulated with qualitative insights from fieldwork in Yogyakarta, Indonesia. Results from this narrower geographical perspective show that urban food environments and the foodways of local residents are resilient to processes of food systems change. Qualitative findings also highlight the key role of individual agency and of contextual socio-economic and cultural factors as moderators of nutritional behaviours. The thesis concludes by highlighting that processes of nutrition transition are highly complex, and that predictions on their outcomes in terms of (nutritional) health are prone to overgeneralisations that can overshadow localised change dynamics. Findings from my research show that, while some of the predicted shifts in diets have occurred in Indonesia, there is evidence that many others have been less dramatic than expected, or have not materialised at all. Rather, my findings suggest the persistence of an enduring negotiation between the desire to retain local traditional diets and the (physical and economic) possibility to do so, amidst rising social and economic disruption. In turn, this highlights the need to account for contextual and localised nuances in the analysis of dietary change processes across LMICs, to better inform interventions that can effectively improve population health.

Osteoarthritis (OA) is a leading cause of pain and disability in the UK for which there is, at present, no effective pharmacological treatment and no cure. Given the prevalence of the disease, there is increasing interest in the impact of nutrition and its potential to contribute both to prevention and treatment. Existing data in this area is both inconsistent and limited. This research investigates associations in two large population based cohorts, in cross-sectional and longitudinal settings, with a particular focus on biological pathways known to contribute to disease development. Data available contained radiographic OA and pain variables in the TWINS-UK cohort, and clinician classified OA and pain variables in the EPIC-Norfolk cohort. Both groups had data on serum lipids and information on dietary exposure obtained through the use of food frequency questionnaires. Genetic data were also available in the EPIC-Norfolk cohort. A cross-sectional analysis was performed in 20517 adults from the EPIC-Norfolk cohort and in 8351 females from the TWINS-UK cohort. Longitudinal analysis investigated incidence and change in hip and knee pain over time in EPIC-Norfolk. Key associations were explored further in a Mendelian randomisation analysis in an attempt to clarify the potential causal relationships between putative exposures and outcomes. The main finding from the FFQ cross-sectional analysis in TWINS-UK is that a ‘Traditional English’ dietary pattern showed a 28% increase in the risk of hand OA. An unexpected result was that the ‘Fruit and Vegetable’ dietary pattern was suggested to increase the risk of knee OA by 19%. Further analysis into the Mediterranean dietary pattern revealed a protective association with OA decreasing the risk of radiographic hand OA by 12%. Analysis of serum lipid levels showed that triglycerides increased the risk of hip OA, hand OA, elbow and forearm pain, and chronic widespread pain. Cholesterol and LDL were also consistently found to increase the risk of OA/pain and the LDL component apoB1 was found to significantly increase the risk of hand OA. Findings from the case-control and longitudinal analysis in EPIC-Norfolk, revealed that increased BMI is strongly associated with hip and knee OA (p<0.0001) and with onset of hip pain (p<0.0001) and knee pain (p=0.0001). Triglycerides were also found to increase knee OA (p=0.023) and knee pain (p<0.0001) in the case-control analysis and were found to increase knee pain in females (p=0.0013). Findings also showed that cholesterol levels increased the risk of future knee pain (p=0.016) and increased vegetable consumption was inversely associated with change in hip pain. The findings from the Mendelian Randomisation study, using SNPs from FTO and APOA5 to investigate reverse causality between BMI and triglycerides and OA, showed no causal associations with OA. In conclusion, data from these two cohorts suggests that a diet high in saturated fats increases the risk of OA/pain as do the serum levels of lipids. Increased consumption of a Mediterranean diet is suggested to be protective of hand OA. Although BMI is strongly associated with hip and knee OA and incidence and change in hip/knee pain over time, both BMI and triglycerides were found not to be causal of OA when explained by genetic variants responsible for changes in these two exposures. Although wider replication is needed to confirm these observations, the results from this research suggest potential dietary modifications for prevention and treatment of OA and pain associated with OA that could be tested further in randomised trials.

Background: There is a need for cost-effective and adaptable health interventions to address complex issues within the UK National Health Service (NHS). Reverse innovation in public health is the process of adapting health interventions developed in low-income countries (LICs) and implementing them in high-income contexts (HICs) (1). This process is gaining traction in global health as a means of offers knowledge sharing between the global south and the global north. The adaptation of interventions from one context to another is ubiquitous and necessary, but the process is often unrecorded. There is a tension between fidelity to the intervention and adaptation to the specific needs of the target context and a heterogeneous population. In the UK, ethnic minority groups in particular experience disproportionate levels of obesity, type 2 diabetes, cardiovascular disease and micronutrient deficiencies compared with the majority White European-origin population (2), and current NHS services are unable to address the increasing rates of nutrition-related ill-health in these populations. Furthermore, there are inconsistencies in the effectiveness of NHS interventions in minority ethnic groups and there is a risk of intervention generated inequalities. Adapting interventions that have been subject to reverse innovation could increase intervention effectiveness in their new context. The aim of this thesis is to present a framework that supports the theoretical adaptation of one such intervention, the women’s group Participatory Learning and Action cycle (PLA cycle) (3) using the Nurture Early for Infant Nutrition (NEON) study (4) in the Bangladeshi population of Tower Hamlets as an exemplar. The framework is intended for multiple policy, practice and research benefits. Failing to follow a framework for implementation could lead to an unsuccessful intervention (5). Methods: This thesis employed a qualitative research design across two studies: 1. The principles of how the women’s group PLA cycle was adapted in practice were captured through Study 1. This study explored the process of adaptation to the women’s group PLA cycle across the original seven cluster randomised controlled trials (RCTs) in Bangladesh, India, Nepal and Malawi through 14 key informant interviews. 2. Study 2 determined the specific contextual adaptations that could address the acceptability and feasibility to the women’s group PLA cycle through focus group discussions (FGDs) with individuals of Bangladeshi-origin from Tower Hamlets. All data were subject to the Braun and Clarke (2006) guidelines to thematic analysis (6). Results: The key informant interviews generated data that resulted in an outline of a generic theoretical adaptation framework. The framework includes components requiring fidelity and those requiring subtle adaptations. The four-stage framework detailed a preparation phase, the process of adaptations and highlighted a specific set of micro-adaptations that can be adjusted to emulate local context. The FGDs aimed to address the micro-adaptations that were suggested by the key informants. They showed a paradoxical relationship between the participants’ Bangladeshi heritage and their lived environment. There were specific differences between individuals who had been in the country for less than three years, those that had been in the country for more than three years, and those that had been born in the UK but whose parents were from Bangladesh. Discussion The women’s group PLA theoretical adaptation framework is the first attempt to create a formal adaptation structure for the PLA cycle which is also relevant to other participatory intervention paradigms. The framework was developed in the context of a wider study about reverse innovation of the women’s group PLA cycle model but would also be relevant to any situation where a participatory intervention is being adapted. Relatively few studies have previously considered the macro policy and political context as a influencers on adaptation processes for health interventions, although this is well characterised in implementation literature (7). Recognising the inherent differences within the Bangladeshi population of Tower Hamlets could allow the women’s group PLA cycle to be adapted appropriately by the NEON study. I believe it is important to adjust the micro-adaptations to encompass both areas of the population’s identity - heritage and environment. This has implications for other interventions that are looking to culturally adapt their interventions for minority populations in the UK. Conclusion: The theoretical adaptation framework for the women’s group PLA cycle is new to the innovation literature, because they outline areas to consider when an intervention developed in a LIC is undergoing reverse innovation. Strength lies in the homogeneity of experience of the key informants, meaning that data had less ‘noise’ in terms of the actual intervention itself. This thesis has constructed a theoretical framework that could potentially assist other researchers with the adaptation of the model into their HIC context.

Micronutrient deficiencies (MNDs), also referred to as hidden hunger, are of global concern with over 2 billion people being at risk. Although MNDs, including iodine (I), iron (Fe) and zinc (Zn), are recognised as being of public health concern especially in sub-Saharan Africa (SSA), there is growing interest in the public health importance of selenium (Se) deficiency, an essential micronutrient important for thyroid and antioxidant functions. Currently, there is limited evidence on the prevalence of Se deficiency at population level in SSA, and there has been little research of potential interventions to address Se deficiency. Based on evidence from small-scale, localised studies, Se deficiency was raised as a potential issue in Malawi and measurement of Se status was included in the Malawi National Micronutrient Strategy of 2013, alongside Zn. This thesis reports how evidence on the Se status of the Malawi population was developed through the inclusion of blood plasma Se measurements from the nationally representative National Micronutrient Survey, as well as new evidence on utility of urine for assessing population Se and Zn status. The plasma Se study comprised >3000 people, including preschool children (PSC, aged 6–59 months, n=1500), women of reproductive age (WRA, aged 15–49 years, n=780), school-aged children (SAC, aged 5–14 years, n=700), and men (aged 20–54 years, n=228). The plasma data revealed long-range geospatial variation in Se deficiency risks being closely linked to soil characteristics, socio-economic status, and proximity to Lake Malawi and the Shire Valley. The geospatial patterns in urine Se concentration based on casual (spot) urine samples (n=1,406) taken from the same sample of WRA (n=741) and SAC (n=665) showed that between-cluster (enumeration area, EA) variation in urine Se concentration corresponded with variation in plasma Se concentration. Geospatial correlation was stronger between urine and plasma Se concentrations – at the EA scale – when urine Se concentration data were adjusted for individual hydration status (e.g. using specific gravity) compared with uncorrected urine. It is concluded that Se deficiency is widespread in Malawi and status is largely driven by environmental factors including soil type. Urine Se concentration appears to be a viable and useful biomarker of Se status, and may be appropriate for population-level surveillance of Se status, being less intrusive than blood plasma sampling. The utility of urine Zn concentration as a biomarker for Zn status was found to be effective. Policy and research recommendations to support the Government of Malawi’s effort in ending the neglected hidden hunger of Se and Zn have been drawn.

Neurodegenerative and neurological diseases are metabolic diseases that invite metabolic treatments. Nutritional interventions that induce a state of ketosis, or “ketogenics,” are one class of metabolic treatment that have the potential to address the root pathologies of such diseases. Presented first in this thesis are three clinical studies that investigated the effects of a ketone ester (KE) drink in patients with Parkinson’s disease. The first study was a randomized, placebo-controlled, crossover trial in 14 participants that demonstrated a significant improvement in endurance exercise performance following a KE drink. Participants sustained a therapeutic cycling cadence of 80 rpm for 24% longer after ingesting KE as compared to performance following a placebo (carbohydrate) drink. The second study utilized ³¹P magnetic resonance spectroscopy in 11 participants and demonstrated that exogenous KE did not alter brain energetics one hour following a drink. The third study was a randomized, placebo-controlled 28-day intervention in which 20 participants were to ingest either KE or placebo drinks four times daily for one month, while motor and non-motor symptoms were monitored. Four participants completed the protocol before the COVID-19 pandemic stopped Oxford clinical studies. Thus, the completed work is included herein as a validation of methods and feasibility study. This thesis also includes intellectual contributions in the form of recent peer-reviewed publications, most of which are literature reviews and theoretical papers, although one is a case report and another is a technological innovation: a tracking tool that has potential to open new avenues in nutrition research. Although the contents of this thesis may appear disparate, they are woven around the narrative that brain disorders are caused by disturbances in metabolism, and that the development of disease-modifying therapies, including ketogenics, will likely require addressing the core metabolic dysfunction that underlies each disease.

Background—The nutritional status of women and children continues to be a global public health concern, particularly in low- and middle-income countries. While improvements have been gained in nutrition-related health indicators In Ethiopia, 38% of children under five remain stunted, 25% of women of reproductive age are undernourished, and an estimated 1.7 million children, pregnant, and breastfeeding women require specialised nutrition support. Maternal dietary and child nutrition is not solely the result of access to food. Orthodox Christianity is practised by an estimated 40 million people in Ethiopia and strictly prohibits the consumption of animal products and restricts the times allowed for eating for the 200 days per year that are designated fasting days; yet, there is little understanding of its practice amongst pregnant and breastfeeding women. Research Aim—To increase our understanding of how and why Ethiopian Orthodox women practice religious fasting during pregnancy and when breastfeeding through their own accounts. Methods— Using a social ecological framework, interviews with pregnant and breastfeeding women explored the interrelated factors that contribute to dietary behaviour during these nutritionally important periods, including social norms and religious decisions around fasting. A sample of 19 participants was selected purposively for interviews from both urban and rural sites in the Amhara Region of Ethiopia. Interviews were conducted in the local language, audio recorded. Using NVivo software, transcribed interviewed were analysed to define thematic areas. Results—Religiosity and its effect on health was a major theme of women’s nutrition experiences which drove their motivation and behaviour, intersecting all other themes and subthemes. There was a closely linked association between women’s experiences of the physical effects of pregnancy, breastfeeding during fasting and the spiritual experience of fasting. Women’s exercise of agency in their fasting behaviour and their conception of health as encompassing both spiritual and physical aspects were identified as major themes. The influence of social networks, including peer, family, and community, also played an important role in women’s dietary choices during pregnancy and breastfeeding. Conclusion—Recognizing spiritual well-being as a normative health framework for Ethiopian Orthodox women may in fact facilitate adoption of the types of multisectoral approaches to undernutrition that are recommended in global health nutrition guidance. Directly involving priests and lay community members as more prominent stakeholders to address undernutrition in this socio-cultural context may result in more effective strategies to reduce nutrition-related maternal and child morbidities and mortality in Ethiopia.

Aim: To explore the interrelationship between functional dentition, food and nutrient intake, and nutritional status among older adults in Thailand. Methods: This was a 12-month longitudinal study of community dwellers, aged 60 years and over, in Phetchaburiprovince (central Thailand). Baseline data were collected through interviews, anthropometric measurements and dental examinations. Dietary intake was assessed with the 154-food-item Thai semi-structured Food Frequency Questionnaire (Thai Elderly-FFQ), from which nutrient intake was estimated via the INMUCAL-Nutrients V4.0 software. Anthropometric measurements included were body mass index (BMI), waist circumference (WC) and triceps skinfold thickness (TSF). Dentists examined the number and condition of teeth (dental caries and severe mobility), functional tooth units and quality of dentures. The follow-up survey collected information on dietary intake and anthropometric measurements only. All associations were tested in linear regression models adjusted forconfounders.

Background: Suboptimal dietary patterns associated with many snack foods, typically high-fat, high-refined carbohydrate foods, that are low in fibre and nutrients, present an easily identifiable target to improve cardio-metabolic health. Meta-analyses of epidemiological and interventional studies have reported that almonds are associated with lower intermediary risk of CVD. However, tree nut and almond consumption levels are unknown in the UK population, and the impact of almond snack consumption on endothelial function and liver fat, as key drivers of CVD, remains unclear. Aim: 1) to investigate the prevalence of tree nut/almond consumption and its association with diet quality and CVD risk in the UK adult population, and 2) to study the effects of snacking on tree nuts, specifically whole almonds, on CVD risk markers, including endothelial function and liver fat as main outcomes, and other metabolic risk factors, in displacement of typical snacks. Methods: In cross-sectional analysis using the UK National Diet and Nutrition Survey (NDNS) data from adult respondents(≥19y), the average consumption of almonds was determined and its association with intermediary CVD risk markers, including body composition and fasting blood lipids using analysis of covariance (ANCOVA) adjusted for covariates was explored. Following a 2-week run-in period consuming control snacks, a 6-week parallel arm trial was undertaken where participants were randomized to isoenergetic treatments: 1) control snacks (mini-muffins) replicating the UK average snack nutrient profile; or 2) dry-roasted whole almonds, providing 20% estimated energy requirement. Endothelial function (via flow-mediated dilation (FMD)), liver fat (via MRI/1H-MRS), heart rate variability (HRV) and other risk measures were assessed at baseline and endpoint. A total of 107 participants (75F,32M; mean age 56.2y, SD 10.4) were randomized and 105 completed the trial.

In the UK there are well recognised socio-economic inequalities in diet and health. However, research about dietary inequalities rarely focuses on young people. Whilst some qualitative research has studied how low-income families manage food and eating, less has examined or compared young people’s food practices in more affluent families. This study takes a mixed methods approach to examine the role of family income and other factors in understanding the food and eating practices of young people (aged 11 – 16 years) in higher-income and lower-income families at home and school. To examine the relationship with young people’s diet quality, secondary analyses of the National Diet and Nutrition Survey (NDNS; 2008/09 - 2013/14) was carried out. To explore the ways in which young people’s diets and food practices are shaped by different contexts, the study employed a case approach using a range of qualitative methods with young people in six higher and 30 lower-income families from one inner London borough. Quantitative analyses of the NDNS show that as household income increases young people’s diet quality also increases. Other factors also appeared to be important: family food purchasing, the young person’s sex, takeaway consumption and mothers’ employment. The qualitative analyses of cases found that lower family income generally constrained the household food budget, limiting young people’s access to quality fresh food. In contrast, higher family income meant families spent more on food and young people had greater access to more nutritious foods. Mothers’ working hours and family food practices related to parental ethnicity were also important. Whilst challenges of bringing together the different data and analyses are noted, it is argued that, in combination, they provide a fuller and more nuanced picture of the ways in which income and other factors influence the diets and food practices of young people.

Background: Non-allergenic perceived food intolerance (PFI) is a distressing condition reported by up to 35% of individuals, whereas the prevalence of food allergy (FA) is 0.9 –3%. The aim of the present paper is to systematically review the evidence for associated psychological, clinical and psychosocial factors in order to improve current understanding of PFI and contribute to future targeted interventions. Methods: Articles published from 1970 until September 2019 were identified through Web of Science, Scopus, PsycINFO, MEDLINE, EMBASE and Global Health. Search terms involved PFI and various synonyms, combinations, operators, truncations, wild cards and limiters. Case-control, prospective cohort, cross-sectional and retrospective studies published in English thata) included a subject population of adults over 18 with PFI and b) examined psychological, clinical and/or psychosocial factors of PFI were reviewed in two stages against inclusion criteria, by three separate reviewers. The methodological quality was assessed, data were extracted, and a narrative synthesis was conducted.

Existing literature exposes poor eating habits and low vegetable consumption as rife amongst adolescents. Increased autonomy in relation to decision-making around food often follows the onset of secondary school education. Studies have shown that adolescents are vulnerable to peer pressure because they want to fit in with their peers. The aim of this research was to develop a detailed insight into young adolescents’ (aged 11- to 13-years-old) behaviour concerning vegetables through exploratory research. The findings will inform the vegetable marketing of the company partner, Puffin Produce (who currently package Welsh fresh produce for supermarkets across Wales). A triangulated research methodology incorporated quantitative and qualitative data collection predominantly from schools in South Wales. Phase One involved collecting data from school canteen purchases (n=3 secondary schools), qualitative school catering manager interviews (n=6), catering staff focus groups (n=14) and parent focus groups (n=5). Phase Two included school canteen observations (n=3 secondary schools) and adolescent focus groups (n=42). A design period preceded the participatory design research with adolescents (n=41) and final parent focus groups (n=16) (Phase Three). Abductive thematic analysis resulted in numerous themes, the three most pertinent being convenience, taste preferences and parenting. This study fills three identified ‘gaps’ in the literature: the novel use of catering staff participants, the geographical research area of South Wales and the incorporation of adolescents in the participatory design research. The original contributions to knowledge includes an understanding into the factors influencing Welsh adolescents’ (aged 11- to 13-years-old) attitudes towards vegetables in addition to their food consumption routines and behaviours. Moreover, these insights are of commercial interest and could potentially inform the marketing communications of food companies seeking to target this market and improve healthful eating. The NPD process resulted in a vegetable-based snacking concept that is innovative yet feasible, suitable for Puffin Produce to develop further.

This thesis presents a body of work that deepens our knowledge and understanding of food environments and drivers of food acquisition practices in transitioning low- and middleincome country (LMIC) settings. It includes critical contributions to food environment theory, a systematic review of evidence from LMICs, the development, application, and evaluation of a novel qualitative geographical information systems (Q-GIS) methodological approach, and a qualitative investigation of the food environment and drivers of food acquisition in periurban Hyderabad, India. The first article presents a new food environment definition, a globally applicable conceptual framework for food environment research, and maps methodological approaches. Critical perspectives suggest how existing knowledge and evidence may be leveraged to accelerate food environment research in LMICs, and key challenges and opportunities are identified. The second article is the first systematic review of food environment research from LMICs. The review reveals the rapidly emerging body of literature from LMICs and provides a synthesis of the evidence base testing for associations between dimensions of food environment exposure and dietary, nutrition and health outcomes. The third article presents the development, application and evaluation of a novel Q-GIS approach that features participatory photo mapping and follow-up graphic- and photoelicitation interviews (n=22) designed to investigate food environments from an emic perspective. Results include participant’s perceptions and experiences of documenting their FE as well as empirical data on the utility and feasibility of this approach. The fourth article presents findings from in-depth interviews (n=18) and the Q-GIS approach (n=22) investigating complex, multi-scalar, and multifaceted drivers of food acquisition in two transitioning peri-urban villages in Hyderabad. Key drivers of food acquisition included: 1) food prices; 2) vendor and product properties, including freshness and quality, and adulteration and contamination; and 3) a sense of community and trust related to known people.

Previous studies and cross-sectional surveys conducted in Malaysia have shown that the prevalence of obesity, diabetes and other non-communicable diseases (NCDs) are associated with poor diet practices. Overeating is contributing to the increasing prevalence of obesity and other NCDs among Malaysians. This study aims to investigate how environmental influences might impact food preferences between Malay and Chinese. Past research shows that ethnicity is related to differences in food-related beliefs, preferences and overall eating behaviour. To investigate how environmental factors might influence food preferences, a series of experiments were conducted using psychological paradigms. First, food consumption patterns using a Food Frequency Questionnaire (Chapter 2) between the two groups were compared. It was found that Malay participants consumed more spicy and savoury foods, and larger portions of both artificially and naturally sweet foods, such as fruits. Overall findings of the FFQ showed that Malay participants consume a higher level of energy intake compared to the Chinese participants, which is reflective of existing literature in Malaysia. Additionally, Malay participants showed a preference for wheat-based foods other than rice- which is staple food in traditional Malay cuisine. In contrast, Chinese participants showed a higher preference for traditional Chinese cuisine for everyday meals such as noodles and porridge. Preferential food selection was examined using a 2AFC method (Chapter 3). Malay participants selected spicy foods more than Chinese participants, and both groups made more preferential selections of savoury foods than they did for spicy foods. Malay participants made the most selections for sweet foods, whereas the Chinese participants chose savoury foods the most. Spicy foods were the least preferred among the Chinese participants, whereas the control food items (e.g. raw vegetables and fruits) were the least preferred among Malays. To understand whether selections made on a 2AFC task are representations of actual preferences; a categorization and ratings task was given to assess participants’ recognition of spicy, savoury, and sweet foods (Chapter 4). Results showed that Malay participants had significantly more errors in categorizing the savoury foods than Chinese participants, while the Chinese participants made significantly more errors in categorizing spicy foods than the Malay participants. Both groups attributed highest ratings of palatability to spicy foods, followed by sweet foods and rated control foods the lowest. The Chinese participants found spicy foods to be higher in flavour compared to the other categories of food. It is proposed that although the Chinese participants might not consume spicy foods on a regular basis, they provided higher ratings of palatability. The effects of semantic priming on categorising different categories of foods flavours between the groups was examined in Chapter 5. It was predicted that the presence of a prime (visual imagery) would interfere with participants’ abilities in characterising target words effectively depending on what category the prime represented. Malay participants had higher errors than Chinese participants in processing target words from spicy, sweet, and control categories although this difference was not significant. Both groups had difficulties in characterising spicy and savoury target words when the prime presented were spicy and savoury food stimulus. The final experiment explored the role memory and familiarization in food recognition abilities across the two groups. Certain types of dishes might be more “salient objects” for one group rather than the other and this could influence food preferences (Chapter 6). Results showed a higher average consumption quotient for spicy, savoury and sweet foods on the R-FFQ among the Malay participants. Malay participants were not more susceptible in discriminating repetitions of spicy and sweet food stimuli more than the savoury and control food stimuli. Although Malay participants exhibited the lowest d’ scores in recognition for the spicy food items, scores were not significantly different from scores in recognizing the other food categories. Chinese participants showed the highest accuracy in recognition for control food items, and no relationship between familiarity and recognition of the savoury food items. We were unable to establish a connection between familiar foods and performance on the recognition task. Cumulatively, the overall findings from this entire investigation raises questions about measures which can effectively measure food selection. For future studies, we hope to employ more indirect, discreet measures in assessing preferential food selection among Malaysians. Overall, the findings show that both groups show a slight predisposition towards flavour components present in their traditional cuisines, but more research needs to be carried out to understand this further.

Whilst mounting evidence implicates innate immune cells such as monocytes and macrophages in the development of atherosclerotic cardiovascular disease, evidence supporting dietary saturated fat intake as an established risk factor has been a topic of recent controversy. Little however, is understood about the effects of acute dietary saturated fat intake on monocytes and their subsets. A dietary interventional study with a coconut oil meal, rich in lauric acid was utilised to investigate human monocyte subset responses to saturated fat intake, comparing fasting and postprandial monocytes in healthy human donors. Utilising ex vivo and in vitro experiments, monocyte subsets differed at baseline in terms of surface marker expression and that the CD16low subset accumulates cytoplasmic lipid droplets to a greater extent than their CD16high counterparts, but that neither subset mounts an inflammatory response to dietary saturated fat exposure at either surface protein or gene expression level. Somewhat unexpectedly however, both subsets of postprandial monocytes lost relative migratory ability towards a chemokine gradient following postprandial lipids exposure and downregulated their inflammatory responses when stimulated by bacterial or viral TLR cues. The effects were augmented further when utilising higher concentrations of postprandial triglycerides in the form of triglyceride-rich lipoproteins and replicated with other dietary lipid sources such as palm and olive oil. Utilising gas and liquid chromatography mass spectrometry, I demonstrated that this surprising immunoparetic phenotype may in part be due to intracellular changes in lipid metabolism and the accumulation of isomers of docosahexaenoic acid (DHA), a polyunsaturated fat with anti- inflammatory properties. Although a significant body of work suggests intake of dietary saturated fat may provoke an inflammatory response, ingestion of lauric and other fatty acids used in this study, in fact resulted in an immunoparetic response, which may be of importance in understanding atherogenesis and healthy eating in the context of immunity.

Unhealthy diets and physical inactivity are important modifiable risk factors for premature mortality and major chronic diseases, such as cardiovascular disease (CVD) and type 2 diabetes (diabetes). However, few large-scale studies have examined the combined influence of overall diet quality and physical activity on longevity and the risk of clinically-diagnosed CVD and diabetes in adults recruited from the general population. Of popular opinion, is the notion that the health risks from poor diets can be compensated by physical activity; i.e. that one can “outrun a bad diet”. The food industry has often sought to sway public opinion towards the belief that dietary indulgences can be enjoyed as long as one engages in sufficient physical activity. However, it is unclear if the risk of premature mortality and cardiometabolic disease from unhealthy diets can be offset by physical activity, and vice versa. Therefore, the overall theme of this dissertation is to examine the epidemiological associations of diet quality and physical activity on the risk of mortality, CVD and diabetes. Specific objectives are to: 1) Study the independent associations of overall diet quality and physical activity on the primary outcomes of all-cause mortality, cardiovascular disease, and diabetes. 2) Examine the dose-response associations between physical activity and the risk of mortality and cardiovascular disease, including more of the evidence base by employing comprehensive exposure dose-harmonisation methods. 3) Examine the interactions between diet and physical activity on the health outcomes: a. If the risk of mortality and cardiometabolic disease from unhealthy diets can be offset by physical activity, and vice versa. (i.e. compensation) b. If diet and physical activity can work synergistically to further lower the risk of mortality and cardiometabolic disease, beyond the independent effect from each exposure alone (i.e. synergism) 4) Quantify the population health impacts of diet and physical activity, in terms of preventable events (deaths and disease cases) associated with both exposures, as well as the population attributable fractions (PAFs) of poor diet and inactivity contextualised with other major lifestyle risk factors. 5) Examine the long-term trajectories of physical activity (increases, decreases, and maintenance) on the risk of mortality. These investigations can bring further clarity to the public health messaging around diet and physical activity for improving longevity and the prevention of cardiovascular disease and diabetes.

A significant amount of energy and resource has been devoted to promoting home food preparation, based on the hypothesis that it is an important, modifiable determinant of diet composition and quality. Ideas about the importance of home food preparation to good nutrition have permeated into policy, with a number of countries emphasising home food preparation and home-prepared food in their dietary guidelines and food guides. These policies encourage individuals to maintain ‘traditional’ domestic food practices in order to eat healthily, even while the food system, along with other dimensions of life such as working hours and leisure activities, are undergoing substantial change. Interventions have often focused on boosting skills, guided in part by public and academic discourse that posits that people are cooking less than they did in the past because they no longer know how. This idea persists despite evidence that most people feel their skill set to be adequate to their needs, and cite other barriers, including, notably, a lack of time. Concerns have been raised surrounding both the effectiveness of encouraging home food preparation as a strategy to improve dietary quality, and its repercussions for equity, with foodwork still being predominantly undertaken by women, and with those who are time-poor being potentially less able to adopt time-intensive approaches to food provisioning. Further, there is a certain lack of clarity surrounding what is being encouraged: not all foodwork produces foods that might be defined as ‘home-prepared’. This thesis aims to present a social epidemiology of foodwork and home-prepared food consumption, using nationally representative data from UK adults to: 1) Investigate how a ‘lack’ of time, in the form of competing demands on and other uses for time, is associated with time allocated to foodwork; and 2) Explore the association between home-prepared food consumption and diet quality. First, analysis of three waves of cross-sectional UK time use surveys, spanning three decades, demonstrated that both participation in foodwork and time spent on foodwork continued to decrease. A compositional data analysis approach was used to put this in the context of other daily activities, examining how time spent on activities such as work, sleep and leisure has evolved in tandem with time spent on foodwork. Results suggest that time devoted to work, paid and unpaid, has not increased substantially over this period. Instead, more time is spent on sleep and screen time. Second, analysis of the most recent wave of the UK time use survey compared how participants who did no foodwork, some foodwork, or a lot of foodwork allocated their time differently. Participants who spent more time on foodwork also spent less time on sleep, although not on screen time. Foodwork was predominantly done by women, and women who did more foodwork increased time spent on work (both paid and unpaid) and reduced time spent on leisure and personal care activities more substantially than their male counterparts. Third, a measure of home-prepared food consumption based on food diaries was developed using data from the UK National Diet and Nutrition Survey, and compared to a more orthodox measure: self-reported frequency of meals being prepared at home in participants’ households. These measures were significantly associated with one another, and this association did not vary systematically between most socioeconomic and demographic groups. Fourth, the food diary-based measure of home-prepared food was deployed to estimate consumption levels in the UK population (around a third of energy intake), and to determine the association between home-prepared food consumption and dietary quality. A moderate, though significant, association was found between the two. However, there was limited variation in the consumption of home-prepared food or its association with diet quality between different socio-demographic groups, suggesting that other components of diet may be responsible for consistently reported inequalities in diet quality. Finally, we explored the possibility of eating healthily where extensive foodwork was not possible or desirable by identifying individuals who ate healthily with minimal reliance on home-prepared food, describing their intake in terms of food and nutrients, as well as their socio-demographic characteristics. As a whole, this work suggests that, while foodwork and home food preparation continue to play a role in how people in the UK spend their time and provision their food, other ways of eating also play an important, and potentially growing, role, and may not always necessarily be detrimental to health. Interventions that seek to improve dietary quality at the population level must take a full account of contemporary life, supporting individuals in eating healthily through a diverse range of approaches to food.

This study investigates how self defined vegetarians in modern Beijing construct their identity through everyday experience in the hope that it may contribute to a better understanding of the development of individuality and self identity in Chinese society in a post traditional order, and also contribute to understanding the development of the vegetarian movement in a non--'Western' context. It is perhaps the first scholarly attempt to study the vegetarian community in China that does not treat it as an Oriental phenomenon isolated from any outside influence. Using qualitative data collected from interviews with vegetarians and non vegetarians, observation and text from social media, this study finds that the motivations behind vegetarians in modern Beijing are highly similar to the motivations revealed in studies of vegetarians in other societies. The religious influence may be especially noticeable in the local context and is often combined with other arguments for vegetarianism, such as ethics. Vegetarians in Beijing have developed different strategies to maintain their vegetarian identity in a mostly non vegetarian society, including taking more control of their own diet, using rhetoric to avoid direct confrontation and making certain compromises. Vegetarianism related organizations are important in forming the vegetarian community, yet a general depoliticisation of vegetarianism in China makes it difficult to strive for more rights for vegetarians. The thesis suggests areas for future research about the vegetarian community in China, the global vegetarian movement and how it may contribute to future policy making.

The routine measurement of the biologically active fraction of calcium 'ionised calcium' is fraught with difficulties. Therefore, an assessment of this fraction is estimated through a mathematical equation using the regression of albumin on calcium. In clinical practice, the most widely used equations for calcium estimation were derived by Payne et al (1973). To date this equation has been derived using hospitalised patients' data after excluding patients with diseases that may disturb calcium metabolism. Since the inception of their use, reports have described many inherent problems with applying a calcium equation to adjust total calcium measurements across different patient groups. However, no robust alternative approach or method for calcium measurement has been proposed by these critics. This study aims to elucidate the reasons behind suboptimal performance of the free calcium estimation (hereafter called adjusted calcium), causes for variability in adjusted calcium reporting as well as exploring new concepts to improve adjusted calcium performance such as the derivation and validation of a population specific equation for ambulant patients. For this purpose, three data sets were collected; first, a retrospective data set from 14 hospitals and communities representing various analytical platforms. These data were collected from all the methods that are commercially available for calcium measurement and were used to derive calcium equations, for hospitalised patients and ambulant patients. The second was a prospectively collected data set. This set was used to validate the newly proposed population specific equation for ambulant patients for a single analytical platform (Roche Cobas). The third data set includes an external quality data set that was collected to assess analytical and post analytical factors that impact on adjusted calcium classifications such as analytical performance goal of calcium and albumin and their reference intervals. Results from this study showed that in comparison to 'ionised calcium', the population specific equation performed better in ambulant patients than an equation derived from hospitalised patients. Replacing creatinine ≤ 200 Âμmol/L with estimated glomerular filtration rate (eGFR) > 60 mL/min/1.732 in the inclusion criteria prior to an equation derivation was without effect whereas replacing the calcium population mean with a mean of 2.4 mmol/L in the equation worsened the equation performance, leading to misclassification of calcium status. Reference interval studies for calcium and albumin showed a wide variation between various analytical platforms and methods. This finding was supported by the analytical performance studies. The Association of Clinical Biochemistry (ACB) proposed approach for data gathering (which includes total calcium values between 2.0 and 2.7 mmol/L) for equation calculation, appears promising and may lead to reduced adjusted calcium variability between laboratories. However, it has been shown that one of the major problems adding to increased adjusted calcium variability is related to analytical variability of the calcium and albumin methods. Albumin methods (Bromocresol green and Bromocresol purple) accounted for significant differences in the classification of adjusted calcium results which was found to be related to a difference in albumin concentrations measured by these assays. The mean albumin concentration of these assays was consistently higher for BCG than BCP methods irrespective of platform. Calcium methods showed a closer agreement with the exception of Siemens calcium assays, for which re-calibration should be seriously considered. This study showed a population specific equation concept can be a solution for improving the adjusted calcium equation in ambulant patients. The same concept opens the door for more sub-division and consideration of an age and gender related adjusted calcium equation. It has been found that standardising adjusted calcium equations and reducing variability in adjusted calcium results is a remote possibility without eliminating albumin and calcium calibration issues. Until these issues are resolved, laboratories should continue deriving their own equations according to Payne's described method. However, the introduction of a population specific equation in combination with the ACB recommended data collection approach is a step forward towards reducing variability in adjusted calcium reporting.

Nutritional epidemiology is a complex area of research plagued with bias and measurement error partly arising from the use of imperfect methods of dietary data measurement and inadequate data analyses. Some foods or nutrients are consumed habitually, while others are consumed occasionally. This thesis addresses three important public health problems: (1) Estimation of under and over consumption of foods consumed occasionally such as alcohol; (2) Investigation of the determinants of food intake, and (3) Estimation of the effect of the intake of occasionally-consumed foods on health outcomes. The analysis of food intake is complicated because foods are often eaten in combination. This gives rise to multiple correlated habitually- and occasionally-consumed food intakes, characterised by a large proportion of zero observations. Modern statistical methods are required to deal with measurement error, excess zeros in the intake distributions, and correlated preferences for frequency of consumption and portion sizes across foods. The thesis demonstrates the use of contemporary statistical methods, based on mixed-distributions and mixed-effects modelling approaches, for the analysis of a single and multiple correlated habitually and occasionally-consumed food intakes. These methods are complex due to the need to evaluate intractable integrals for parameter estimation. Firstly, to describe under and over consumption, the thesis provides a new numerical approach, which is a quicker and simpler alternative to Monte Carlo simulation, to estimate the distributional quantiles of occasionally-consumed food intakes in predefined sub-populations. Secondly, dietary data from the UK National Diet and Nutrition Survey Rolling Programme (NDNS RP), which provides the only source of current authoritative information on food and nutrient intake in the UK, are analysed with a mixed-effects two-part model to estimate the associations between personal and socio-economic risk factors and the intake of several foods of current public health importance. % This is the first time this approach is applied to NDNS RP data to assess explicitly socio-economic and personal characteristics related to occasionally-consumed food intakes in the UK population. Then, the thesis develops a novel multivariate joint model for several correlated occasionally-consumed food intakes utilising a pseudolikelihood approach and parametric bootstrap for parameter estimation. The approach is illustrated by modelling the intake of alcohol, jointly with the intake of other foods, and the resulting analysis is compared with that based on the two-part model for a single food and the traditional multivariable linear regression model widely used in nutritional epidemiology. Finally, a regression calibration approach is applied to correct for the effect of excess zeros and multiple correlated person-specific preferences when several food intakes are investigated as predictors of health outcomes. Again the results are contrasted with those obtained by applying multivariable regression analysis which ignores excess zeros and correlated preferences, introducing potential bias in the effect estimates. As an example, the relationships between alcohol intake in a male sub-population of NDNS RP and haemoglobin A1c (HbA1c), a known predictor of type 2 diabetes mellitus, are investigated. Ideally, to obtain unbiased estimates of predictors' effects, all correlated unobserved person-specific effects should be accounted for. However, the task is incredibly complex and to tackle this the suggestion is to simplify the model by accounting only for the largest residual correlations. Even in this imperfect form, regression calibration produces markedly different results from multivariate linear regression.

Adolescence is a period of transition in which the individual changes physically and psychologically from a child to an adult. Relative to other age groups, less is known about the diet of young Singaporeans. The aim of this work was to examine the eating habits of the mid and late adolescents, aged 17 to 21 years old, in Singapore. This age group was selected as they formed the post-secondary cohort in which, they have more autonomy in their food choices and are not bounded by school canteens. Dietary habits were compared between different genders, ethnicities, BMI classes and educational institutes. A particular focus of the study was on diet quality, breakfast intake, out-of-home eating and snacking habits. Multiple pass 24-h recalls and focus groups were used to examine the dietary habits of participants from an ITE (Institute of Technical Education), JC (Junior College) and POLY (polytechnic). A healthy eating index (HEI-SG) and three models for snacking were developed as part of the work. A total of 507 participants (100 participants each from ITE and JC, 307 from POLY) were recruited for the multiple pass 24-h recalls and six focus groups (36 participants from POLY, of which there were 18 Chinese, 9 Malays and 9 Indians) were conducted. Overall median HEI-SG scores were low at 47.2 (IQR 16) out of 100 due to an insufficient intake of total fruits, whole fruits, total vegetables, whole grains, dairy products and a high intake of sodium. More than 55% of the energy intake per day (56.58%, IQR 61.4% for female and 56.77%, IQR 52.7% for male) for both genders was contributed from food purchased out of home. It appeared that almost a third of Singaporean post-secondary students in this sample did not consume breakfast. Snacking behavior appeared frequent but estimation of this was hampered by the lack of a universally accepted definition. Three criteria and models for defining a snack were developed and tested. Divergent number of snacks/snackers were obtained, depending on the criterion used. This is the first study to use the 24-h recall method to assess the dietary intake of late adolescents living in Singapore. Public health strategies to address the low intake of fruits, vegetables, whole grains and dairy products and the high intake of sodium and frequent skipping of breakfast in this population group are recommended.

Iodine is an essential trace mineral. Iodine deficiency during pregnancy can lead to adverse postnatal consequences such as impaired mental development, reduced intelligence scores and impaired motor skills in the offspring of the deficient women (Khazan et al., 2013, Rayman et al, 2008). There is growing evidence in the UK of low dietary iodine intakes and potential iodine deficiency in vulnerable populations (pregnant women and women of child bearing age group) (Rayman and Bath, 2015, Vanderpump et al., 2011) and a paucity of information on the iodine content of food products. In developing countries where iodine deficiency is widespread, salt has successfully been used as a vehicle for iodine fortification, however iodised salt is not widely available in UK supermarkets and there are valid health concerns about promoting salt intake. Salt is an essential component of the cheese production process, and cheese is commonly consumed in the UK. The overall aim of the present study was to explore the use of iodised salt in cheese production to improve the iodine status in the UK. In order to accomplish this, 4 smaller interconnected aims were identified namely development of method and subsequent analysis of iodine content of cheese samples in the UK, examining these results in relation to the legislative policies regarding iodine fortification practised in the country of production of cheese, understanding about the knowledge, attitudes and practices of consumers regarding iodine nutrition and fortification through a survey and then finally manufacturing popularly consumed cheese varieties (soft cheese and cheddar – from the consumer survey) using iodised salt and comparing it with cheese made with non- fortified regular table salt in terms of iodine content and overall sensory acceptability. A cheese mapping exercise was conducted to gain an overview of cheese varieties available across three major supermarkets in the UK and their country of origin. Selected varieties of cheese were analysed for their iodine content which was subsequently mapped against legislation policies (mandatory or voluntary) for iodine fortification in their country of origin. A questionnaire was designed to explore the knowledge attitude and practices (KAP) of general consumers about the use of iodised salt in food products. After pilot testing and minor modifications, the questionnaire was used to obtain KAP data from general consumers (n=506). To explore the use of iodised salt in cheese production, a collaboration between UCLan and Food technology centre (Anglesey) was established. Two varieties of cheese (cheddar cheese and soft cheese) with two variations (with and without iodised salt) were developed. Sensory acceptability was assessed by both expert (at Cardiff Metropolitan University) and non-expert consumer (at UCLan) panels. The newly developed cheese samples were analysed for their iodine content to evaluate their potential as a novel vehicle of improving dietary iodine intake. The iodine content of cheese samples from countries with mandatory legislation ranged from 0.16mg/kg for creamy Danish blue cheese (from Denmark) to 0.76mg/kg for Canadian cheddar. From countries with voluntary legislation, the range in iodine content was much broader, from 0.08 mg/kg (Swiss Le Gruyere) to 0.92 mg/kg (Farmhouse Cheddar). Analysis of milk and salt samples revealed that the iodine content of all the selected salt samples produced in the UK was negligible. Consumer KAP survey results revealed a general lack of awareness about significance of iodine for optimal health with only 11% participants aware that it is ‘Extremely important’ for maintaining optimal levels of iodine in the body and a high percentage of participants (81%) were not aware of any illness associated with iodine deficiency. 11% of consumers reported seeing brands of iodised salt in supermarkets, indicating low availability in the UK and most (62%) expressed a preference for non-iodised salt. The survey also revealed that 61% of respondents reported consuming cheese more than once a week and that Cheddar cheese was the most popular variety. The iodine content of the soft and hard cheese made with iodised salt was higher (0.92 mg/kg and 0.77mg/kg respectively) than those made with regular salt (0.76mg/kg and 0.48mg/kg respectively). Sensory evaluation of this cheese by sensory experts and general consumers revealed the use of iodised salt in place of regular salt had no significant impact on the main attributes (colour, appearance, taste, texture, odour and overall quality) or specific characteristics (sweetness, bitterness, aftertaste, creamy odour, saltiness) of the cheese (Chi Square test p > 0.05). In conclusion, this research has revealed that on a global scale, mandatory iodine fortification policy may result in more consistency in the iodine content of cheese. In a sample of the UK population, there was a lack of awareness of the importance of iodine for human health. The research demonstrated that replacing non-iodised salt with iodised salt in the production of both soft and hard cheese increased the iodine content of the cheese by 21% and 60% respectively and had no detectable impact on the sensory attributes, thus is potentially a useful vehicle for iodine fortification in the UK.

Objectives: Research suggests that a reduction in calories may impact cognitive functioning in healthy adults. Despite studies that demonstrate changes to cognitive function following periods of fasting and continuous calorie restriction, any potential impact for those who follow intermittent fasting (IF) diets remains unclear. Among the most popular IF diet is the 5:2 fasting diet. Proponents of this dieting regime claims that it has numerous benefits to general health. Less in known about the impact of this diet on cognition. Given that some studies have shown cognition is impaired following acute fasting, concerns remain about the impact of a fasting diet that encourages high levels of intermittent calorie restriction. This study sought to understand the impact on specific areas of cognition for healthy adults who follow the 5:2 diet. Methods: Part A Using a within-subjects repeated measures design, 36 healthy adults who were following the 5:2 diet for more than four weeks were measured for cognitive performance on fasting and non-fasting days using a range of online cognitive tasks. Specifically, we measured cognitive flexibility, working and prospective memory, reflective impulsivity and psycho-motor speed. Part B Using a between-subjects design, mean performance on the cognitive tasks for healthy adults following the 5:2 diet (n=36), was compared to those following CCR diets (n=30). Both groups had been following their diets for more than four weeks. Results: Part A Cognitive flexibility, working and prospective memory was impaired on fasting days along with a reduction in impulsivity. Overall composite scores revealed impaired reaction time and accuracy on fasting days. Part B Participants following the 5:2 diet performed worse than those following CCR diets in tasks designed to measure psycho-motor speed and cognitive. Overall composite scores revealed impaired reaction time for those following 5:2 diets, compared with those following CCR diets. Conclusions Research that investigates the impact of calorie restriction and fasting on cognitive function should also consider the potential risks of cognitive impairment for those who choose to follow intermittent fasting diets. Future studies would benefit from longer term measurement of cognition for those following IF diets whilst accounting for potential confounding variables.

The short-term effects of exercise on appetite and ad libitum energy intake have received considerable interest as a potential strategy to reduce the prevalence of obesity over the past two decades. The experiments in this thesis have further investigated this topic by examining the appetite and the ad libitum energy intake responses in anticipation of an acute bout of aerobic exercise session. To achieve this, healthy, regularly active males and females (M= 55; F= 34; mean ± SD: age 24± 5 years; BMI 23.4± 3.2kg/m2) were recruited into four studies. The aim of the experiments in this thesis was to focus on the behavioural aspects of appetite and energy intake,and therefore, gut hormone responses were not investigated. In Chapter IV, a hypothetical exercise scenario (i.e. 60 minute hard aerobic exercise session) prompted a ~24% increase in the planned energy intake as opposed to a hypothetical rest scenario in regular exercisers. In Chapter V, we further demonstrated that anticipation of an aerobic exercise session (30 minutes cycling at 75% HR-max; 30 minutes running at 80% HRmax) led to an increase in planned energy intake for breakfast compared to a resting control trial. However, differences in planned energy intake did not result in any differences in the actual ad-libitum energy intake in the post-exercise or rest period. Chapter VI revealed a novel and a reproducible method to measure evening energy intake with a food pack that contained preweighed food items. This method was then employed for the following two chapters to measure evening food intake. Chapter VII investigated the effect of a planned 60 minute late-afternoon aerobic exercise session on appetite and energy intake both before (i.e. at breakfast and lunch) and after (i.e. over the evening) exercise compared to an identical resting control trial. The results indicated that a partial compensation (~11% increase in energy intake at lunch in the exercise trial) takes place during the preceding meal in response to a planned exercise session. However, this increase in energy intake at lunch was not sufficient to offset the energy deficit created by the exercise session, and therefore, still resulted in a negative energy balance (EB) in the short-term. Finally, Chapter VIII showed that this compensatory behaviour is still apparent in the preceding 24 hours and resulted in a ~10% increase in energy intake when compared to a resting control in anticipation of an aerobic exercise session, although this compensatory increase was still not sufficient to offset the energy deficit created by the exercise. Taken together, this thesis has shown that ad-libitum energy intake is affected by the anticipation of an aerobic exercise session. Moreover, although this compensatory increase in energy intake is not sufficient to offset the energy deficit created by the exercise session, it furthers our understanding of the effects of exercise on eating behaviour and the need for an explicit study design to explore the effects of exercise on appetite and energy intake in a laboratory setting. The results from this thesis can partially explain the discrepancies observed with the long-term exercise intervention studies that report less than expected amounts of weight loss.

Background: Takeaway foods have increased in popularity over the past 40 years and there has been much debate regarding the determinants of their consumption. Whilst takeaway foods are thought to be associated with a number of non-communicable diseases, wider dietary patterns may be more predictive of disease risk than individual foods due to the synergistic effects of food combinations. However, accurate measurement of habitual food, particularly energy-dense nutrient-poor foods, using self-reported dietary assessment tools can be subject to participant bias. Recent research has demonstrated that metabolites derived from individual foods present in urine samples provide biomarkers of dietary exposure. Aim of PhD: To investigate takeaway food consumption within wider dietary patterns of a Merseyside population and their socio-demographic and lifestyle determinants. Additionally, to identify novel metabolite biomarkers from urine samples associated with takeaway foods as a means of validation of self-reported food consumption. Methods: Study 1) Design a food frequency questionnaire (Eating Habits Survey (EHS)) and conduct pilot (n = 26) to test the efficacy of methods prior to a larger scale study. Study 2) Record habitual and takeaway food consumption of study population (n = 1724) using the EHS and use principal component analysis (PCA) to determine dietary patterns. Study 3) Validate the EHS using three 24 hour ‘Multiple Pass’ dietary recalls (3 x 24 h MPR) and metabolomics on urine samples from a sub-sample (n = 151) from Study 2. Results: Being male, in a younger age group, having children in the household, alcohol use and smoking were positively associated (p < 0.05) with takeaway food consumption, whereas being in an older age group 3 and having higher qualifications were negatively (p < 0.01) associated. Nevertheless, specific takeaway food groups were associated at varying degrees. PCA identified some contrasting dietary patterns from the EHS and 3 x 24 h MPR, many of which included ultra-processed foods, and two concurring major patterns; ‘Western’ and ‘Prudent’. Metabolomics determined, for the first time, differences among the metabolite fingerprints of takeaway food consumers, and has shown good biomarker potential for kebab, Indian, English and Chinese takeaway food. Metabolomics validated self-reported dietary intake and determined urinary metabolites associated with habitual exposure to specific foods including poultry, coffee, alcohol, cocoa, oils, and fruit and vegetables. Conclusion: This research makes a novel contribution to knowledge and offers valuable insight into the determinants of takeaway food consumption and wider dietary patterns in the UK adult population. Moreover, it has built on an innovative metabolite fingerprinting technique that distinguishes food exposure from urinary samples. These findings should inform further research in this highly topical area and provide the evidence base to influence the formation of policy and interventions on takeaway food locally and in other areas.

This thesis addresses challenges Malaysia faced in weight management. Issues, aims, objectives and thesis layout were explored and explained in chapter one. Chapter two delves on technical details of overweight and obesity; its cause, consequence and measures with past studies and relevant theories critically evaluated. Chapter three explored experiences of 46 selected individuals that previously engaged in weight loss/maintenance and cultural impact as barrier through a semi-structured interview. Although most have good knowledge on obesity, they lack motivation and self-regulatory skills. Challenges included societal norms and peer pressure; with time and commitment were most difficult to overcome. Malays and Indians ethnicities mentioned need of family members to be present at meal times. Family, work or social gatherings required participants to join in and eat together to avoid causing offense. Chapter four explored weight management experiences of 4971 individuals using a survey and model predictors of weight loss success. Majority attempted weight loss at least once, are minimally active, few sought professional help and most wishing for more weight loss success but very few were successful. The first predicting model revealed sex, physical activity level and treatment control as strongest predictor but having 2.3% variance predictability. The second model predictors were physical activity level, treatment control, emotional representations, timeline cyclical, high caloric food score, identity and timeline with a higher variance of 31.7%. Chapter five analysed Body Image Scale’s (BIS) potential as a proxy measure for BMI in a Malaysian population. Individuals presently engaging either on weight loss attempts or maintenance can match their BMI correctly to corresponding image on BIS. Participants with BMI < 25.0 tend to overestimate their position on the BIS and vice-versa for those with BMI > 25.0. Chapter six concluded in proposing some key ideas for intervention development and use of results in existing programmes the MoH is implementing.

Omega-3 polyunsaturated fatty acids (n-3PUFA) ingestion is associated with multiple health benefits, including improved brain and heart function. Research examining the influence of n-3PUFA supplementation on indices of athletic performance remains limited, with studies administering various dosing strategies in an attempt to improve recovery from muscle damaging exercise, revealing mixed findings. Currently, protein is the most common nutritional strategy to improve recovery from muscle damage however, studies have shown mixed results. As n-3PUFA supplementation is known to exhibit anti-inflammatory properties, combining n-3PUFA with protein in supplement form may promote recovery from muscle damaging exercise. This thesis demonstrates that coingesting n-3PUFA with protein serves to reduce muscle soreness and attenuate the rise in putative blood markers of muscle damage following an intense bout of exercise in soccer players. However, there were no improvements in soccer-skill performance observed with n-3PUFA and protein supplementation. The mechanism(s) underpinning the improvement in recovery with n-3PUFA supplementation is not currently known but may relate to the increase in n-3PUFA composition within skeletal muscle. Dietary n-3PUFA ingestion has been shown to exhibit protective effects on lean tissue during periods of skeletal muscle catabolism such as leg immobilisation and in disease states. This thesis demonstrates that during short-term (2-wk) weight loss, increased dietary n-3PUFA intake fails to attenuate the decline in lean body mass during energy restriction. However, n-3PUFA supplementation improved muscle strength despite the reduction in muscle mass. The explanation for the improvement in muscle strength with n-3PUFA supplementation may be related to a modification of neuromuscular function. This thesis also examined the biological role of the antioxidant, curcumin, to facilitate the incorporation of n-3PUFA into whole blood and the phospholipid membrane of skeletal muscle. However, we demonstrated that the addition of curcumin to an n-3PUFA-based supplement did not facilitate tissue incorporation of n-3PUFA into blood or skeletal muscle. The explanation for this null finding unclear, but may relate to the dose of curcumin and/or n-3PUFA administered in the supplementation regimen. Abstracts containing actual data are included within each experimental chapter.

The overall aim of my thesis was to investigate the associations between ultra-processed food consumption (UPF) and cardiometabolic health at the individual and the population-level while adhering to methodological principles such as incorporating and presenting a multiverse of statistical results and interpreting statistical hypothesis testing in a non-dichotomous way. I addressed these aims in three studies: a systematic review and meta-analysis of 41 prospective cohort studies, an ecological, longitudinal cross-country comparison, and a prospective analysis in the UK EPIC-Norfolk cohort. The research presented in this dissertation revealed consistent associations between UPFs and adverse cardiometabolic health. The results of the systematic review and meta-analyses of chapter 2 provided the first systematic analysis of published nutritional epidemiology studies from the perspective of food processing. I defined UPF consumption more broadly and identified studies in which UPF consumption had been termed in several different but related ways, such as fast, convenience, or Western foods. I combined those diets and dietary pattern studies that were characterized by a higher relative intake of UPFs in non-linear and summary random-effects meta-analysis estimates. Higher intakes of UPFs were associated with both an increased risk of cardiovascular diseases (CVD) and type 2 diabetes mellitus (T2DM). Higher sales of UPF were associated with an increased risk of adiposity and diabetes mellitus in the country-level analysis in chapter 3, using data from 76 countries across all five continents over 16 years. The panel analysis demonstrated that a strong and consistent association existed between the sales of UPFs at the food system level and adiposity and diabetes prevalence in low-to-middle-income countries (LMICs) for children, adolescent, and adult populations, as well as for both sexes separately. This finding adds value to the literature because no previous study had systematically investigated these associations in countries in which often a lack of individual data exists and had estimated associations for LMICs and high-income countries (HICs) separately. However, the analysis did not establish an association between UPF and adiposity in HICs, which was surprising, given that previous studies indicating an association at the individual level were mostly from HICs. The lack of variability in UPF data from HICs during the study period were likely a key reason for the lack of estimated associations in HICs. As a consequence of the many combinations of data processing and analytical methods and the variability of point estimates and P-values, no particular set of point estimates was emphasized, but the consistency of findings indicate that the expansion of global adiposity and diabetes since 2000 can partially be attributed to the increased sales of UPFs, at the level of the food system or country. The associations that were found in the meta-analysis and the panel study were replicated in prospective analyses of detailed data from over 17,000 individuals in the EPIC-Norfolk cohort, yielding associations between increased UPF intake and adiposity as well as risk of T2DM and CVD. This study demonstrated that the way UPF intake is operationalized can fundamentally influence results. Previous UPF studies had only expressed UPFs as weight or the proportion of food weight, with the justification that energy measures would not capture the non-calorific components of UPFs with potentially adverse effects on health. Guided by previous nutritional epidemiological research to adjust for total energy intake, I modelled UPF and disease risks in five different ways. The analyses revealed that these different approaches affect the statistical results, but also that they affect the results differently for different diseases. For example, the differences between measures of UPF intake based on energy and weight were much more pronounced for T2DM as an outcome than for CVD, suggesting that potentially different mechanisms relating to dietary energy and other factors common to UPFs might be responsible for different outcomes. Chapter four was also the first research to comprehensively test the associations between UPF and three important cardiometabolic disease outcomes (adiposity, T2DM, and CVD) in a prospective cohort with a long follow-up period. The findings of an almost consistent positive association provide the strongest evidence to date that UPFs are positively associated with adverse risk of cardiometabolic health. The secondary analyses of eight different food groups and outcomes indicated that greater consumption of ultra-processed meat, fish, and eggs; fast foods; and SSBs are associated with an increased risk of T2DM and CVD, whereas consumption of ultra-processed fruits and vegetables, milk and diary, fats, and breads and cereals might not be associated with an increased risk of disease. Bodyweight is likely a very important mediator of the association between UPF and T2DM and CVD, while increased total energy intake through UPFs is likely the most important driver of the UPF-adiposity association.

Obesity is a worldwide rising pandemic disease and a great challenge for healthcare systems due to its associated disorders. Exercise, drugs and all sorts of dietary plans are typical weight loss options that overweight or obese individuals are offered besides more radical actions such as bariatric surgery. However, weight loss is sometimes incremental, especially at the very start of a regimen and this often leads to the patient dropping-out of a dietary program. Hence, there is a need to identify biomarkers that are affected over a 24-hour interval and use them to provide quantitative biofeedback on the efficiency of a diet. It would also allow personalised optimisation of dieting parameters with relevance to short-term. There is also a need to understand the effects of various food on these biomarkers and the mechanisms by which the food affects adipose tissue metabolism in particular. This thesis describes for the first time the identification of insulin, lactate and angiotensin converting enzyme (ACE) as potential biomarkers of weight loss. Decreased levels of these biomarkers were observed in the urine of individuals following a low-calorie diet. Importantly, these changes preceded weight loss and were consistently associated with weight loss on the long term. Therefore, insulin, lactate and ACE are biomarkers that may be used to assess the metabolic benefits of a diet in its early stages where weight loss is not always a reliable parameter. Further, nutritional means are identified by which ACE could be regulated and it is found that lemon extract (LE) down regulates ACE activity in adipocytes and is associated with both improved adipose insulin sensitivity and increased lipid mobilization. In a proof of concept study, biomarkers have been identified that could provide molecular feedback on food intake behaviour.

The proportion of the British population reducing their consumption of animal food products has increased dramatically over the last decade, while vegetarian and vegan options are now widely available in supermarkets and restaurants across the UK. This phenomenon presents vital benefits for climate change, environmental degradation, human health and animal welfare. Yet, little research has investigated the rapidly growing trend. A broader understanding of the decision to reduce one's consumption and the cognitive, social and physical processes involved in maintaining dietary changes is essential for policy makers, campaigners and researchers working toward a sustainable future. Meat reduction and vegan campaigns by non-governmental organisations serve as a primary promoter of reduction and present a unique opportunity to research reducers when they may first be seeking a dietary transition. The theoretical framework employed within this dissertation combines the first comprehensive model of behaviour change, the Behaviour Change Wheel (Michie, Atkins and West 2014), with the fields of social consumption and sustainable and ethical consumption to analyse the reducer and the reduction process through a more comprehensive framework. A mixed-methods approach has been used to investigate the barriers, motivators and goals of participants in seven UK-based meat reduction and vegan campaigns through focus groups (n=33) and a longitudinal web-based survey (n=1,587). To the best of the researcher's knowledge, this represents the most comprehensive study of reducers and reduction campaigns to date. Interviews with campaign staff (n=13) and an examination of campaign messaging and strategies have been used to further analyse campaign participation and the reduction process. Findings reveal key trends within highly diverse approaches to reduction, including a reduction hierarchy that prioritises red meat and neglects fish and egg reduction through a tendency for small, gradual dietary changes. While meat reducers were likely to be successful on a short-term basis, they were unlikely to maintain reductions over a prolonged period. Those with the greatest levels of abstention were, instead, the most likely to meet their reduction goals. Animal protection also emerged as key for many reducers, potentially creating a new perspective - a mindshift - that re-positions the animal source within the consumption process. Findings suggest that policy makers, campaigners and advocates need to consider the psycho-social element within the reduction process, with the potential for a wide variety of consumer types and, importantly, the need to not simply address what is consumed but to address normative omnivorous consumption that is formed around a meat component and de-values meatless meals.

Breakfast, which is typically consumed within 2-3 hours after waking up, is considered by many to be the most important meal of the day. Its carbohydrate (CHO) content ranges between 50-60% of its energy, meaning breakfast could replenish carbohydrate (glycogen) stores after a long overnight fast. A number of studies have shown the detrimental effect of omitting breakfast on endurance exercise, however, little is known about the effects on resistance exercise. Considering the prevalence of omitting breakfast among exercisers, commonly due to logistical/practical reasons, examining breakfast consumption versus omission on resistance exercise performance is of particular interest. To initially investigate this, the study reported in Chapter 3 compared performance in 4 sets to failure of back-squat and bench press at 90% of 10 repetition maximum (10-RM), between an ecologically valid breakfast (BC), containing 1.5 g carbohydrate/kg body mass, and a water only breakfast (BO). As hypothesised, total repetitions of back squat and bench press were less during BO compared to BC. Correspondingly, hunger was elevated, whilst fullness was decreased in the BC condition. These results demonstrate that omission of a pre-exercise breakfast might impair resistance exercise performance. However, it cannot be discounted that, as subjects were aware of when they were consuming breakfast or not, that the exercise performance responses were confounded by psychological factors (i.e. placebo/nocebo effects). Therefore, a double-blind study was conducted (Chapter 4), with the aim to compare resistance exercise performance after consuming a water only control breakfast (WAT) or two identical semi-solid breakfasts, one a virtually energy-free placebo (PLA), the other containing 1.5 g carbohydrate/kg body mass (CHO). CHO and PLA breakfasts were eaten with a spoon from a bowl and contained 4.25 mL/kg body mass water, 0.75 mL/kg body mass sugar-free orange squash and 0.1 g/kg body mass xanthan gum as a thickener, with addition of 1.5 g/kg body mass of maltodextrin in the CHO breakfast. Back-squat total repetitions were greater in both CHO and PLA compared to WAT. Correspondingly, CHO and PLA similarly suppressed hunger and increased fullness relative to WAT. This study indicated that breakfast likely exerted its effect on resistance exercise performance via a psychological effect. However, when higher volume resistance exercise was applied (Chapter 5), consisting of sets of 10 repetitions of leg extension to exhaustion at 80% 10-RM, an ergogenic role of carbohydrate was evident, as CHO produced greater total repetitions compared to PLA. Whilst the studies in Chapter 3 and 4 suggested that breakfast influenced performance via a psychological effect, appetite also responded correspondingly, raising the question as to whether appetite might influence resistance exercise performance. In a follow-up study (Chapter 6) two breakfasts containing 1.5 g carbohydrate/kg body mass were provided, but one included 0.1 g/kg body mass of xanthan gum (SEM), whilst the other did not (LIQ), with the aim of manipulating appetite without affecting carbohydrate intake. Interestingly, back squat total repetitions were greater following the SEM compared to LIQ and this correspond with decreased hunger and increased fullness in SEM compared to LIQ. In conclusion, the results from these experiments demonstrate that the perception of breakfast consumption, rather than carbohydrate/energy per se, improves resistance exercise performance. The ergogenic role of pre-exercise carbohydrate only seems to benefit extremely high-volume resistance exercise performance. Whether these effects are still apparent when pre-breakfast/meal glycogen stores are not optimal is unknown (i.e. if a not fully replaced from a previous training session). However, when subjects are well-fed, high-intensity intermittent exercise like resistance exercise might be influenced by sensation of fullness and a pre-exercise meal might exert its effects through this novel mechanism. In situations where the amount carbohydrate or the metabolic effects of the carbohydrate consumed before exercise are unlikely to influence performance (such as resistance exercise), consumption of meals that decrease sensations of hunger might be a simple strategy to enhance performance.

A woman’s diet quality and level of physical activity during pregnancy will influence both her own health and the lifelong health of her offspring. From the earliest stages of development, a baby’s health and long-term risk of disease are programmed according to its mother’s nutritional status and body composition, among other factors. One way of improving the health of the next generation is therefore to intervene during pregnancy, supporting women to improve their health behaviours, and give their offspring the best possible start. Pregnancy is often viewed as a teachable moment when women are more motivated to improve their health for their babies’ benefit. However, many pregnant women gain weight that exceeds guidelines and do not meet recommendations for physical activity, showing that more needs to be done to support women to make a change during pregnancy. It is clear from the literature that the factors that influence diet and physical activity in pregnancy are complex and wide-ranging, and many of these factors influence one another. For this reason, a complex adaptive system framework underpins this thesis with a particular focus on individual-level factors as these have not previously been conceptualised as a complex system. This work was undertaken to inform the development of future interventions to support women to improve their diet and physical activity behaviours in pregnancy. First, questionnaire data were analysed to identify key factors associated with diet and physical activity in mothers of childbearing age. This analysis identified that social support, self-efficacy for healthy eating, perceived control, food involvement and positive outcome expectancies were associated with diet quality and that self-efficacy for physical activity was associated with women’s level of physical activity. The second study comprised a systematic review of behaviour change interventions in pregnancy that aimed to increase physical activity or improve diet quality, and that also aimed to improve at least one individual-level factor that may mediate or moderate intervention effectiveness. Nine studies were identified. Narrative synthesis of these studies showed that knowledge and planning were both amenable to change and associated with changes in behaviour. Finally, a qualitative study that included interviews with recently pregnant women, and focus groups with pregnant women, was undertaken to gain a richer understanding of women’s experiences in pregnancy and their engagement with available behaviour change support. Women’s interest in improving their health behaviours, and their engagement with available sources of support, appeared to be closely linked to the extent to which they identified as healthy people. Thus, ‘health identity’ is a key concept that emerged from this research. Data from the qualitative work also showed that pregnancy-specific symptoms such as nausea make it difficult for some women to make a change, even if they intend to do so, and that women’s interest in their own health is an important factor that affects their motivation to change. The findings from these three studies have been incorporated into a complex adaptive systems model, which may be used to inform the development of future interventions to support pregnant women to improve their diet quality or increase their levels of physical activity.

Despite the recognised importance of diet for health in older age and how common poor diet quality and nutritional status are at this stage of the life course, little is known about the complexity of influences on diet quality at this age, particularly in community-living people. Furthermore, there is limited understanding of how a transition between relatively good quality diets in early old age, to poorer quality diets and greater risk of malnutrition observed at older ages, might occur. In this project, participants were recruited from the Hertfordshire Cohort Study (HCS) and focus groups were run to explore influences on diet among community-dwelling older people living in the county of Hertfordshire, UK. Drawing upon the qualitative findings, a secondary data analysis of previously collected HCS data was carried out to identify psychosocial correlates of diet quality in older community-dwelling men and women, and determine their associations with change in diet quality over 10 years. This was followed by a mapping study in the local context of the city of Southampton, to describe services or interventions available to local community-dwelling older people that might support their diets. This study formed part of the process evaluation of the GENIE (Generating Engagement in Network Involvement) pilot intervention study. The last piece of work was a pilot study of the GENIE social network intervention, which was carried out in a group of older community-dwelling adults in the Southampton area. In this pilot study, the potential of improving social networks to promote diet quality was evaluated. The findings from the qualitative study suggested that social and psychological factors were important influences on diet and that they may mediate some of the effects of age-related factors on the diets of older people. Findings from the quantitative study showed that a range of social factors, including greater participation in social and cognitive leisure activities, were associated with diets of better quality in cross-sectional analyses. The mapping study identified a range of services that could support the diets of community-living older people in Southampton, however these did not appear to be adequately joined-up. The results of the pilot study suggest that a social network intervention of this kind may hold promise for the promotion of diet quality of community-based older adults. This thesis has added to the evidence-base on influences on older people’s diets, particularly in a UK context. It has especially highlighted modifiable factors, such as social isolation, that could be targeted in interventions and public health strategies to promote the diets and health of community-living older adults. Further larger intervention studies, with appropriate evaluation, are needed to establish the effectiveness of such interventions. In addition, psychological factors such as resilience, self-efficacy and outcome expectancies, should also be considered as a part of such strategies. It may be crucial for these interventions to be put in place early on to prevent decline in diet quality and associated poor health outcomes.