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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.

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.

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 maternal diet high in fruits and vegetables is associated with increased placental size and birthweight and decreased incidence of preeclampsia. This relationship is not explained by maternal socioeconomic status or levels of micro- and macronutrients in the diet, suggesting that an, as yet, unaccounted for nutrient could be contributing to fetal growth. Extracellular vesicles (EVs) are a recently identified component of fruits and vegetables. EVs are nanosized lipid-encased parcels of protein, RNA and other molecules that can alter the function of recipient cells. Fruit and vegetable EVs are internalised into mouse intestinal cells. It was, therefore, hypothesised that EVs from plants consumed as part of the diet would be internalised into human intestinal cells, resulting in the transmission of plant and/or intestinal-derived signals to the placenta, altering placental growth, development or function and thereby linking maternal fruit and vegetable intake to fetal growth. EVs derived from watermelon (WMEVs) were isolated using ultracentrifugation and found to be of a size and morphology consistent with the EV subtype known as exosomes. Mass spectrometry and qPCR arrays were used to identify that WMEVs exhibit protein, lipid and miRNA profiles that differ from watermelon cells, suggesting that their contents are likely actively loaded. Further analysis of the WMEV proteome predicted a possible dual origin from the endosome and plastid for these WMEVs and suggested they may have a role in watermelon fruit ripening. WMEVs were labelled with a lipid (PKH26) or RNA (SYTO RNAselect) dye and incubated apically with Caco-2 cells differentiated on transwell membranes into small intestinelike epithelial cells. Flow cytometry determined that PKH26-labelled WMEVs were internalised into Caco-2 cells in a time (49.45% of cells at 180 minutes; p < 0.0001) and dose-dependent (R2 = 0.99; p < 0.0001) manner, resulting in increased Caco-2 proliferation (7.12-fold increase; p < 0.05). WMEV RNAs, including microRNAs (analysed by qPCR array), were transferred by WMEVs into Caco-2 cells (96.16% of cells at 240 minutes; p < 0.0001) and through the Caco-2 tight barrier to the basal media compartment (16.36% apical-basal crossover; p < 0.05). Proteomic analysis of this conditioned basal media (WMEV-CBM) revealed alterations to the Caco-2 secretome (5 proteins > 1.5-fold upregulated; 13 proteins > 1.5-fold downregulated) in response to WMEVs. Caco-2 secretion of fetuin-A, an inhibitor of extravillous trophoblast (EVT) migration and trophoblast viability, was decreased (4.3-fold lower; p < 0.01) by exposure to WMEVs. Proteomic analysis of placental trophoblast BeWo cells exposed to WMEV-CBM predicted beneficial alterations to several trophoblast parameters, which were investigated experimentally. WMEV-CBM induced expression of 6 syncytialisation genes and increased cell-cell fusion in BeWo cells (1.44-fold increase; p < 0.01) and primary cytotrophoblasts (1.75-fold increase; p < 0.001). WMEV-CBM was also found to decrease apoptosis (1.98-fold; p < 0.01 in BeWo cells) and increase EVT migration (2.17- fold; p < 0.001) from first trimester placental explants. These data suggest that plant EVs, such as WMEVs have the potential to impact upon placental development, growth and function, potentially linking maternal fruit and vegetable intake to improved fetal growth. With further research, this could inform dietary advice in pregnancy and the development of plant EV-based therapies for pregnancies at risk of fetal growth restriction or preeclampsia.

Diet related chronic disease is a global problem related to millions of deaths worldwide. To encourage healthier diets, a greater understanding of the determinants of food choice is necessary. Food choice is a complex, multifaceted process, with a wide range of non-price determinants of food choice. Economic studies tend to focus on the importance of price factors and categorise non-price determinants as individual preferences. The aim of this thesis is to investigate the role of non-price determinants of food choice, specifically exploring how perceived barriers towards healthy eating, time preference, and signposting a food tax can influence food choices. Analysis of the Scottish Health Survey identified associations between perceived barriers to healthy eating and fruit and vegetable consumption. Results show perceiving healthy foods as too boring or not liking the taste of healthy foods were associated with lower fruit and vegetable consumption for men and women. A lack of willpower was reported as the most commonly reported perceived barrier to healthy eating. Time preference is a concept closely related to willpower and to investigate the impact of dietary choices further, primary data were collected to estimate the relationship between time preference and diet. No association between time preference and diet was observed in this study. The effect of signposting a food tax on food purchases was tested using two methods: a discrete choice experiment and field experiment. The discrete choice experiment found that the tax signpost was significantly associated with food choices whilst the field experiment showed no effect. These contradictory results may be explained by the majority of participants failing to notice the signpost in a real-world setting, compared to the discrete choice experiment which was completed online. To conclude, this thesis highlights that non-price determinants of food choice play an important role in the understanding of food choices.

Dietary fibre and mixed link ß-glucans found within oats and barley may reduce the risk of cardiovascular disease and colorectal cancer. Little is known about how oat fibre consumption influences the gut microbiota. Here we investigated the effects of enzymatically pre-digested oats on microbial activity and composition using a combination of in vitro techniques. Pure culture and batch culture experiments identified specific bacteria could grow on oat fibre. Fermentor experiments identified Roseburia spp., Lactobacillus spp. and Desulfovibrionales spp. were found in greater numbers specifically in the mucin environment, while Bacteroides spp. and F. prausnitzii were more abundant in the liquid environment. Time had a significant impact on both butyrate production and the abundance of butyrate producing species. Differences in the output of short chain fatty acids (SCFA) between experimental conditions was apparent. In batch culture systems butyrate was the most abundant SCFA detected from oat fibre fermentation compared to acetate in the fermentor system. Oat fibre was more fermentable under higher pH conditions and more SCFA were detected at pH 6.5 compared to 5.8. This suggests that in vivo most of the fermentation of oat fibre may likely take place in the distal colon. Bacteroides spp. are known to prefer higher pH conditions, such as those found in the distal colon, and grew consistently on oat fibre. All cereal samples used were obtained from Orkney College, and detailed agronomic and nutritional analysis was performed on different cultivars of oats and barley as part of this project. Cereal trials identified that Scandinavian oat and barley cultivars were viable alternatives to native Scottish crops for growers in the North of Scotland. Scandinavian cultivars produced higher yields, thousand grain weights and had a similar growing period to cultivars more regularly grown in Scotland. As expected the environment has a bearing on the nutritional and agronomic performance of cultivars, in terms of yield and protein and starch content.

Lifestyle choices threaten to compromise health and performance of trained athletes. This thesis presents a series of studies which broadly investigated the impact of nutritional and physical challenges to human health and performance. The potential causes and effects of fluid imbalances on physical health, immune function and athletic performance were investigated. Certain populations experience chronic low-level hypohydration and athletes often fail to rehydrate sufficiently between exercise sessions. The long-term implications of hypohydration are not fully understood, but are suggested to be associated with chronic disease. In this thesis, maintenance of fluid balance was observed in healthy males, despite a caffeine intervention thought to cause diuresis. Furthermore, when mild hypohydration was induced by 24-h fluid restriction, there was little impact on mucosal immunity during endurance exercise compared with euhydration. The impact of intensified training (IT) on the physical, mental, hormonal and immunological status of well-trained athletes was investigated. A performance-specific nutritional intervention was implemented to investigate the effects of nutrient availability during prolonged exercise training sessions. Phases of IT are a regular feature of a periodised training programme. However, an imbalance between training and recovery can have significant implications for long-term athletic performance and general wellbeing. Changes in neuroendocrine, neurobiological and mucosal immune function were observed during IT and some potential markers of overreaching and were identified. Further research is required before practical application of these markers can be used effectively in the field. A relatively short period of IT resulted in significant disruptions to mood state and sleep quality. Minor changes in exercise performance were observed. Markers of overreaching were highly individual, as were responses to training.

Background: Participating in meaningful activities, and maintaining identity, are each embedded within best practice guidelines to improve mental well-being among older adults in the United Kingdom. Food plays a part in many meaningful activities that are important to health and wellbeing. Although there is moderate evidence that participating in food activities contributes to identity maintenance and change, only six studies include British older adults. Aim: To explore the relationship between food activities and identity maintenance among community-living older adults in West London. Methods: A concurrent mixed-methods design from a pragmatist perspective was used. Data collection included semi-structured interviews with 39 older adults (60 to 89 years). Qualitative data were analysed using grounded theory methods. Quantitative methods were used to investigate the relationship between demographic data, transformed qualitative data, and the Occupational Performance Measure of Food Activities. Q methodology data were analysed using centroid factor estimation and interpretation, and triangulated with the qualitative and quantitative components using qualitative matrix analysis and quantitative methods. Findings: This study found three predominant past and present identities as ‘food-lover’, ‘non-foodie’ and ‘not bothered’. These food identities are defined as a composite sense of who one is, derived from one’s experience of participating in food activities. Maintenance of food identities was explained in the processes of ‘Participation and maintenance’, ‘Threat and compensation’, and ‘Changes in meaning and identity’. These processes varied according to the importance and meaning of food activities for each participant. There was no consistent relationship between maintenance or change in food identities, and participants’ hoped-for, feared and expected possible selves. Conclusions: Participation in food activities maintains older adults’ important identities and mental wellbeing when food activities are an important and pleasurable part of daily life. Nevertheless, older adults whose food activities and identities change continue to experience mental well-being in later life.

This thesis summarises a series of academic publications that make a contribution to the field of sports nutrition over a period of 30 years. It begins with research in the field of carbohydrate and endurance sport reflecting the early era of research into carbohydrate and endurance performance, and evolves into studies investigating the impact of sports nutrition and hydration on team sports. It presents papers and other peer reviewed outputs that focus on the application of scientific knowledge to enhance human performance, whilst demonstrating the increasing awareness of the relative importance of carbohydrate and hydration in a range of both female and male team and individual sports. The thesis also highlights the challenge faced by the manufacturers of sports nutrition products in making use of advances in science to develop new and innovative products. The thematic nature of this thesis shows how sports nutrition continues to evolve. As science identifies new and legal means of enhancing human performance, so sport, athletes and coaches will demand more advanced and specialised approaches to refuelling and hydration. This thesis draws together findings from a series of publications which demonstrate how scientists, coaches, athletes and sports nutrition manufacturers need to work closely together to research, identify and interpret the next stages in an exciting and demanding area of research. It also reflects the scientific advancement in the field of sports nutrition over a thirty year period, identifies possible areas for future research, and the continued application of hydration and nutrition strategies to enhance male and female endurance and team sports.

Background: Dietary zinc recommendations vary widely across Europe. The EURRECA (European Micronutrient Recommendations Aligned) Network of Excellence was brought together to harmonise the approach to setting micronutrient recommendations. The overall aim was to produce a set of guidelines and an extensive database that may be of use to expert panels in underpinning future micronutrient recommendations, based on a series of systematic reviews and meta-analysis of published data. A secondary aim was to identify gaps in knowledge regarding micronutrient status, intake and health outcomes for future research. A third aim, coming from the result of the secondary aim, was to investigate the long term effect of supplementation on cognition. Objectives: The objectives of this thesis were: (1) To adapt the methodology for undertaking a systematic review and meta-analysis developed by EURRECA for zinc in all population groups (infants, children, adolescents, pregnant and lactating women and adults and elderly). (2) To identify knowledge gaps in the research through the assessment of the interrelationships between zinc intake, status and health outcomes. (3) To design and implement a study to explore the intake-status-health relationships between micronutrient supplementation and cognitive function in Peruvian children. Methods: Phase 1: The EURRECA systematic review. Database searches were conducted in MEDLINE, Embase and the Cochrane library, from inception to March 2014. For the assessment of the intake-status relationship, an intake-status regression coefficient (^) was estimated for each individual study and the overall pooled ^ and SE ^ was calculated using random effect meta-analysis on a double log scale. The systematic review included randomized controlled trials, cohort studies, cross sectional studies and nested case-control studies in healthy children and adult populations that measured zinc intake (diet and supplements) and zinc status (serum/plasma zinc) in association health outcomes that included cognitive function and psychomotor development. Phase 2: Empirical study. This included the assessment of multiple micronutrients (MMN) supplementation and cognitive development in Peruvian children when compared with giving iron supplements alone. These tests were considered to reflect theoretical dimensions of working memory (Nine boxes), and inhibitory control (Day/Night stroop task). Intelligence Quotient (IQ) was measured using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI); social-emotional behaviour was assessed via the Brief Infant–Toddler Social and Emotional Assessment (BITSEA) and reasoning through the theory of mind test. Results: Meta-analysis of data reporting zinc intake and status revealed that doubling intake increased plasma zinc concentration by 9% in children, by 3% during pregnancy, by 1% during lactation and by 6% in adults and elderly. The systematic review of zinc and health outcomes highlighted the need for further research on the relationship between micronutrients and cognitive function. The empirical study was therefore designed and undertaken. The results revealed that there were no significant differences between the iron and the MMN supplemented groups for all cognitive tests, with the exception of the vocabulary WPPSI subtest in girls (mean±SD), (MMN, 6.83±2.05; iron 5.78±1.59, p = 0.028) and no significant differences were found for plasma zinc and haemoglobin concentrations between the two groups. Conclusions: The systematic reviews provided novel dose-response estimates between zinc intake-status that could be used either qualitatively or quantitatively with balance studies when setting future zinc recommendations. Following an assessment of the impact of micronutrient supplementation on cognitive and social-emotional development in Peruvian preschool children, it can be concluded that MMN supplements had no long term additional effects on cognitive function compared with iron alone, however the timing of the supplement for maximal potential benefit needs to be explored further.

Survivors of critical illness suffer from a range of problems affecting physical, psychological and social well-being (Needham et al 2011). Weakness, fatigue and malnutrition are highly prevalent during the months following a critical illness. Few studies have systematically and comprehensively explored the factors that influence nutritional recovery or ways to overcome them. The aim of this study was to provide a comprehensive understanding of the factors influencing nutritional recovery, and the relationship between them, in post intensive care (ICU) patients. A model of care was then developed to improve current management of nutrition for patients recovering from critical illness. Grounded theory methodology was used with a mixed method research design. Nutritional status and intake were assessed on discharge from ICU and at three months post ICU discharge. The process of nutritional recovery during the first three months post ICU discharge was explored from a patient perspective and at the level of ward organisation of care, through observation of practice and interviewing patients and staff. Seventeen patients, who had required greater than 48 hours ventilation, were recruited on discharge from the ICU. On transfer to the ward 9 of the 17 patients were assessed as well-nourished and 8 were malnourished using Subjective Global Assessment. At three months post ICU discharge 14 patients were followed up (1 lost to follow up, 1 incapacitated following illness and 1 went overseas). Seven of these were classified as well-nourished and the other 7 were malnourished. Patients universally failed to meet their nutritional targets during their ward stay and although intakes had improved by three months post ICU discharge, the majority of patients were still not achieving their nutritional requirements. Qualitative data revealed that patients' nutritional intake was influenced by interrelated system breakdowns during the recovery process; this emerged as the overarching core theme. Three sub-themes were ‘experiencing a dysfunctional body’, ‘experiencing socio-cultural changes in relation to eating and ‘encountering organisational nutritional care delivery failures’. This study identified connections and interrelations between these concepts and provided new insights into the factors that influence the nutritional care of post ICU patients. In order to optimise nutritional rehabilitation in this patient group a model of care has been developed which addresses the identified organisational and patient related factors that were shown to influence the nutritional recovery of patients after critical illness. This nutritional strategy will need to be evaluated in clinical trials or quality improvement programmes.