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Climate protection and other environmental concerns render it critical that diets and agriculture systems become more sustainable. Mathematical optimization techniques can assist in identifying dietary patterns that both improve nutrition and reduce environmental impacts. Here we review 12 recent studies in which such optimization was used to achieve nutrition and environmental sustainability aims. These studies used data from China, India, and Tunisia, and from 7 high-income countries (France, Finland, Italy, the Netherlands, Sweden, the United Kingdom, and the United States). Most studies aimed to reduce greenhouse gas emissions (10 of 12) and half aimed also to reduce ≥1 other environmental impact, e.g., water use, fossil energy use, land use, marine eutrophication, atmospheric acidification, and nitrogen release. The main findings were that in all 12 studies, the diets optimized for sustainability and nutrition were more plant based with reductions in meat, particularly ruminant meats such as beef and lamb (albeit with 6 of 12 of studies involving increased fish in diets). The amount of dairy products also tended to decrease in most (7 of 12) of the studies with more optimized diets. Other foods that tended to be reduced included: sweet foods (biscuits, cakes, and desserts), savory snacks, white bread, and beverages (alcoholic and soda drinks). These findings were broadly compatible with the findings of 7 out of 8 recent review articles on the sustainability of diets. The literature suggests that healthy and sustainable diets may typically be cost neutral or cost saving, but this is still not clear overall. There remains scope for improvement in such areas as expanding research where there are no competing interests; improving sustainability metrics for food production and consumption; consideration of infectious disease risks from livestock agriculture and meat; and researching optimized diets in settings where major policy changes have occurred (e.g., Mexico's tax on unhealthy food)., (Copyright © The Author(s) 2019.)

Background: Non-communicable diseases are the leading cause of death in England, and poor diet and physical inactivity are two of the principle behavioural risk factors. In the context of increasingly constrained financial resources, decision makers in England need to be able to compare the potential costs and health outcomes of different public health policies aimed at improving these risk factors in order to know where to invest so that they can maximise population health. This paper describes PRIMEtime CE, a multistate life table cost-effectiveness model that can directly compare interventions affecting multiple disease outcomes., Methods: The multistate life table model, PRIMEtime Cost Effectiveness (PRIMEtime CE), is developed from the Preventable Risk Integrated ModEl (PRIME) and the PRIMEtime model. PRIMEtime CE uses routinely available data to estimate how changing diet and physical activity in England affects morbidity and mortality from heart disease, stroke, diabetes, liver disease, and cancers either directly or via raised blood pressure, cholesterol, and body weight., Results: Model outcomes are change in quality adjusted life years, and change in English National Health Service and social care costs., Conclusion: This paper describes PRIMEtime CE and highlights its main strengths and limitations. The model can be used to compare any number of public policies affecting diet and physical activity, allowing decision makers to understand how they can maximise population health with limited financial resources.

Background: An increasing number of countries are implementing taxes on unhealthy foods and drinks to address the growing burden of dietary-related disease, but the cost-effectiveness of combining taxes on unhealthy foods and subsidies on healthy foods is not well understood., Methods and Findings: Using a population model of dietary-related diseases and health care costs and food price elasticities, we simulated the effect of taxes on saturated fat, salt, sugar, and sugar-sweetened beverages and a subsidy on fruits and vegetables, over the lifetime of the Australian population. The sizes of the taxes and subsidy were set such that, when combined as a package, there would be a negligible effect on average weekly expenditure on food (<1% change). We evaluated the cost-effectiveness of the interventions individually, then determined the optimal combination based on maximising net monetary benefit at a threshold of AU$50,000 per disability-adjusted life year (DALY). The simulations suggested that the combination of taxes and subsidy might avert as many as 470,000 DALYs (95% uncertainty interval [UI]: 420,000 to 510,000) in the Australian population of 22 million, with a net cost-saving of AU$3.4 billion (95% UI: AU$2.4 billion to AU$4.6 billion; US$2.3 billion) to the health sector. Of the taxes evaluated, the sugar tax produced the biggest estimates of health gain (270,000 [95% UI: 250,000 to 290,000] DALYs averted), followed by the salt tax (130,000 [95% UI: 120,000 to 140,000] DALYs), the saturated fat tax (97,000 [95% UI: 77,000 to 120,000] DALYs), and the sugar-sweetened beverage tax (12,000 [95% UI: 2,100 to 21,000] DALYs). The fruit and vegetable subsidy (-13,000 [95% UI: -44,000 to 18,000] DALYs) was a cost-effective addition to the package of taxes. However, it did not necessarily lead to a net health benefit for the population when modelled as an intervention on its own, because of the possible adverse cross-price elasticity effects on consumption of other foods (e.g., foods high in saturated fat and salt). The study suggests that taxes and subsidies on foods and beverages can potentially be combined to achieve substantial improvements in population health and cost-savings to the health sector. However, the magnitude of health benefits is sensitive to measures of price elasticity, and further work is needed to incorporate potential benefits or harms associated with changes in other foods and nutrients that are not currently modelled, such as red and processed meats and fibre., Conclusions: With potentially large health benefits for the Australian population and large benefits in reducing health sector spending on the treatment of non-communicable diseases, the formulation of a tax and subsidy package should be given a more prominent role in Australia's public health nutrition strategy., Competing Interests: LJC is a member of the Editorial Board of PLOS Medicine.

Objectives: To model food group consumption and price of diet associated with achieving UK dietary recommendations while deviating as little as possible from the current UK diet, in order to support the redevelopment of the UK food-based dietary guidelines (now called the Eatwell Guide)., Design: Optimisation modelling, minimising an objective function of the difference between population mean modelled and current consumption of 125 food groups, and constraints of nutrient and food-based recommendations., Setting: The UK., Population: Adults aged 19 years and above from the National Diet and Nutrition Survey 2008-2011., Main Outcome Measures: Proportion of diet consisting of major foods groups and price of the optimised diet., Results: The optimised diet has an increase in consumption of 'potatoes, bread, rice, pasta and other starchy carbohydrates' (+69%) and 'fruit and vegetables' (+54%) and reductions in consumption of 'beans, pulses, fish, eggs, meat and other proteins' (-24%), 'dairy and alternatives' (-21%) and 'foods high in fat and sugar' (-53%). Results within food groups show considerable variety (eg, +90% for beans and pulses, -78% for red meat). The modelled diet would cost £5.99 (£5.93 to £6.05) per adult per day, very similar to the cost of the current diet: £6.02 (£5.96 to £6.08). The optimised diet would result in increased consumption of n-3 fatty acids and most micronutrients (including iron and folate), but decreased consumption of zinc and small decreases in consumption of calcium and riboflavin., Conclusions: To achieve the UK dietary recommendations would require large changes in the average diet of UK adults, including in food groups where current average consumption is well within the recommended range (eg, processed meat) or where there are no current recommendations (eg, dairy). These large changes in the diet will not lead to significant changes in the price of the diet., Competing Interests: Competing interests:  AK reports funding from Public Health England, during the conduct of the study; funding from European Commission: 7th EU Framework Programme Small Collaborative Project CLYMBOL (contract no. 311963), outside the submitted work. PS reports grants from Public Health England, grants from British Heart Foundation, during the conduct of the study. KS reports that she is an employee of Public Health England during the conduct of the study. MR reports grants from Public Health England, grants from British Heart Foundation and is the Chair of Trustees for Sustain, during the conduct of the study. This work was commissioned by Public Health England who provided data used and were involved in discussions around the methods and analyses., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Objective: To evaluate what is known about the relative health impacts, in terms of nutrient intake and health outcomes, of diets with reduced greenhouse gas emissions (GHGE)., Design: We systematically reviewed the results of published studies that link GHGE of dietary patterns to nutritional content or associated consequences for health., Setting: We included studies published in English in peer-reviewed journals that included data on actual and modelled diets and enabled a matched comparison of GHGE with nutrient composition and/or health outcomes., Subjects: Studies included used data from subjects from the general population, who had taken part in dietary surveys or prospective cohort studies., Results: We identified sixteen eligible studies, with data on 100 dietary patterns. We present the results as dietary links between GHGE reduction and impact on nutrients to limit (n 151), micronutrient content (n 158) and health outcomes (n 25). The results were highly heterogeneous. Across all measures of 'healthiness', 64 % (n 214) of dietary links show that reduced GHGE from diets were associated with worse health indicators. However, some trends emerged. In particular, reduced saturated fat and salt are often associated with reduced GHGE in diets that are low in animal products (57/84). Yet these diets are also often high in sugar (38/55) and low in essential micronutrients (129/158)., Conclusions: Dietary scenarios that have lower GHGE compared with average consumption patterns may not result in improvements in nutritional quality or health outcomes. Dietary recommendations for reduced GHGE must also address sugar consumption and micronutrient intake.

Objective: To estimate the cost-effectiveness of fiscal measures applied in remote community food stores for Aboriginal Australians., Methods: Six price discount strategies on fruit, vegetables, diet drinks and water were modelled. Baseline diet was measured as 12 months' actual food sales data in three remote Aboriginal communities. Discount-induced changes in food purchases were based on published price elasticity data while the weight of the daily diet was assumed constant. Dietary change was converted to change in sodium and energy intake, and body mass index (BMI) over a 12-month period. Improved lifetime health outcomes, modelled for the remote population of Aboriginal and Torres Strait Islanders, were converted to disability adjusted life years (DALYs) saved using a proportional multistate lifetable model populated with diet-related disease risks and Aboriginal and Torres Strait Islander rates of disease., Results: While dietary change was small, five of the six price discount strategies were estimated as cost-effective, below a $50,000/DALY threshold., Conclusion: Stakeholders are committed to finding ways to reduce important inequalities in health status between Aboriginal and Torres Strait Islanders and non-Indigenous Australians. Price discounts offer potential to improve Aboriginal and Torres Strait Islander health. Verification of these results by trial-based research coupled with consideration of factors important to all stakeholders is needed., (© 2015 The Authors.)

Objective: The aim of this study is to provide an overview of interventions to reduce or prevent overweight or obesity and improve diet or physical activity., Methods: A review of meta-analyses and/or systematic reviews of these interventions in any setting or age group were conducted. Narrative systematic reviews were included for intervention categories with limited meta-analyses available. Summary measures including weighted mean difference, standardised mean difference, and I-squared, were examined., Results: A total of 60 meta-analyses and 23 systematic reviews met the inclusion criteria. Dietary interventions and multi-component interventions targeting overweight and obesity appeared to have the greatest effects, particularly in comparison with workplace or technology or internet-based interventions. Pharmaceutical and surgical interventions produced favourable results for specific population sub-groups (i.e. morbidly obese). Population-wide strategies such as policy interventions have not been widely analysed. The effectiveness of the interventions to assist in maintaining behaviour or weight change remains unclear., Conclusions: Various individually targeted interventions were shown to reduce body weight, although effect sizes were typically modest, and the durability of effects has been questioned. New approaches to evaluating population-based interventions, such as taxes and regulation, are recommended. Future research modelling the long-term effects of interventions across the lifespan would also be beneficial., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Concern about the overconsumption of unhealthy foods is growing worldwide. With high global rates of noncommunicable diseases related to poor nutrition and projections of more rapid increases of rates in low- and middle-income countries, it is vital to identify effective but low-cost interventions. Cost-effectiveness studies show that individually targeted dietary interventions can be effective and cost-effective, but a growing number of modeling studies suggest that population-wide approaches may bring larger and more sustained benefits for population health at a lower cost to society. Mandatory regulation of salt in processed foods, in particular, is highly recommended. Future research should focus on lacunae in the current evidence base: effectiveness of interventions addressing the marketing, availability, and price of healthy and unhealthy foods; modeling health impacts of complex dietary changes and multi-intervention strategies; and modeling health implications in diverse subpopulations to identify interventions that will most efficiently and effectively reduce health inequalities.

Background: Fruits and vegetables are an essential part of the human diet, but many people do not consume the recommended serves to prevent cardiovascular disease and cancer. In this research, we evaluate the cost-effectiveness of interventions to promote fruit and vegetable consumption to determine which interventions are good value for money, and by how much current strategies can reduce the population disease burden., Methods/principal Findings: In a review of published literature, we identified 23 interventions for promoting fruit and vegetable intake in the healthy adult population that have sufficient evidence for cost-effectiveness analysis. For each intervention, we model the health impacts in disability-adjusted life years (DALYs), the costs of intervention and the potential cost-savings from averting disease treatment, to determine cost-effectiveness of each intervention over the lifetime of the population, from an Australian health sector perspective. Interventions that rely on dietary counselling, telephone contact, worksite promotion or other methods to encourage change in dietary behaviour are not highly effective or cost-effective. Only five out of 23 interventions are less than an A$50,000 per disability-adjusted life year cost-effectiveness threshold, and even the most effective intervention can avert only 5% of the disease burden attributed to insufficient fruit and vegetable intake., Conclusions/significance: We recommend more investment in evaluating interventions that address the whole population, such as changing policies influencing price or availability of fruits and vegetables, to see if these approaches can provide more effective and cost-effective incentives for improving fruit and vegetable intake.

Objective: Intensive weight loss programs that incorporate dietary counselling and exercise advice are popular and are supported by evidence of immediate weight loss benefits. We evaluate the cost-effectiveness of two weight loss programs, Lighten Up to a Healthy Lifestyle and Weight Watchers., Methods: Health gains from prevention of chronic disease are modelled over the lifetime of the Australian population. These results are combined with estimates of intervention costs and cost offsets (due to reduced rates of lifestyle-related diseases) to determine the dollars per disability-adjusted life year (DALY) averted by each intervention program, from an Australian health sector perspective., Results: Both weight loss programs produced small improvements in population health compared to current practice. The time and travel associated with attending group-counselling sessions, however, was costly for patients, and overall the cost-effectiveness ratios for Lighten Up ($130,000/DALY) and Weight Watchers ($140,000/DALY) were high., Conclusion: Based on current evidence, these intensive behavioural counselling interventions are not very cost-effective strategies for reducing obesity, and the potential benefits for population health are small., Implications: It will be critical to consider other strategies (e.g. changing the 'obesogenic' environment) or explore alternative methods of intervention delivery (e.g. Internet) to see if they offer a more cost-effective approach by effectively reaching a high number of people at a low cost.

Background/Objectives It is not known if diets lower in greenhouse gas (GHG) emissions are also healthier. We evaluated the population health implications of changing to more sustainable diets in the UK, France, Finland, Italy and Sweden. Subjects/Methods We developed a life table model to simulate mortality and morbidity from diet-related diseases over the lifetime of the current population. Populating the model with locally available data for each country, we simulated the impact of country-specific dietary scenarios that had been optimised to meet dietary recommendations and reduce GHG emissions. Outcome measures included a change in disease-specific deaths, life expectancy and disability-adjusted life years (DALYs). Results Diets that meet nutritional recommendations lead to substantial improvements in population health, ranging from 0.19 (95% uncertainty interval: 0.18-0.21) DALYs per person in Italy up to 0.89 (0.80-0.98) DALYs per person in Finland. Simultaneously reducing GHG emissions does not reduce the size of this impact, and in some cases produces additional health benefits. If sustainable diets can be maintained throughout adulthood, life expectancy would increase by between 2.3 (1.6-3.2) and 6.8 (5.5-8.5) months by country. However, results are sensitive to assumptions about how quickly changes in diet can influence disease, and future trends in disease. Conclusions Modelling the health impact of diets that are both nutritional and low in GHG emissions shows the potential for significant co-benefits in health and sustainability from dietary changes. Future work is needed to find effective interventions to deliver healthy sustainable diets., Author(s): Linda J. Cobiac [sup.1] , Peter Scarborough [sup.1] Author Affiliations: (1) Centre on Population Approaches for Non-Communicable Disease Prevention, Big Data Institute, Nuffield Department of Population Health, University of [...]

Aims: We used data from a recent systematic review to investigate weight regain after behavioural weight management programmes (BWMPs, sometimes referred to as lifestyle modification programmes) and its impact on quality‐of‐life and cost‐effectiveness. Materials and Methods: Trial registries, databases and forward‐citation searching (latest search December 2019) were used to identify randomized trials of BWMPs in adults with overweight/obesity reporting outcomes at ≥12 months, and after programme end. Two independent reviewers screened records. One reviewer extracted data and a second checked them. The differences between intervention and control groups were synthesized using mixed‐effect, meta‐regression and time‐to‐event models. We examined associations between weight difference and difference in quality‐of‐life. Cost‐effectiveness was estimated from a health sector perspective. Results: In total, 155 trials (n > 150 000) contributed to analyses. The longest follow‐up was 23 years post‐programme. At programme end, intervention groups achieved –2.8 kg (95%CI –3.2 to –2.4) greater weight loss than controls. Weight regain after programme end was 0.12‐0.32 kg/year greater in intervention relative to control groups, with a between‐group difference evident for at least 5 years. Quality‐of‐life increased in intervention groups relative to control at programme end and thereafter returned to control as the difference in weight between groups diminished. BWMPs with this initial weight loss and subsequent regain would be cost‐effective if delivered for under £560 (£8.80‐£3900) per person. Conclusions: Modest rates of weight regain, with persistent benefits for several years, should encourage health care practitioners and policymakers to offer obesity treatments that cost less than our suggested thresholds as a cost‐effective intervention to improve long‐term weight management. Registration: The review is registered on PROSPERO, CRD42018105744. [ABSTRACT FROM AUTHOR]

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This paper estimates the cost-effectiveness of a 20% price discount on healthy food and beverages with and without consumer nutrition education, as trialled in remote Northern Australia. Changes in actual store sales, from the pre-discount baseline period, were analysed for population impact on consumption of fruit and vegetables, water and artificially sweetened soft drinks, in addition with total dietary weight (grams), energy (Mega Joules), and sodium (milligrams). Disability Adjusted Life Years (DALYs), arising from changes in dietary risk factor prevalence in the population, were estimated as the primary health outcome in a multi health-state Markov model. The costs of the strategies were sourced from paid invoices and time estimates of staff providing store-based discount promotion and consumer education. The incremental cost-effectiveness ratio adopted a partial societal perspective, (including health and retail sector costs), as cost per DALY averted and was presented in 2011 Australian dollars. The price discount, helped address a gap in food price equity for residents of remote communities. However, the discount strategy, with or without consumer education led to a net loss of population health –36 95%CI (-47,-25) or -21(-28, -15) DALYs respectively, at increased cost to the retail and health sectors, of AUD860000 95%CI (710000, 1million) or AUD500000 (410000, 590000). The strategies trialled were thereby categorised as dominated by current practice while acknowledging considerable uncertainty surrounding the health outcome estimates. The 20% discount on limited targeted products appeared to need to be considered in conjunction with other marketing strategies to support healthy food choices, if remote Australian Indigenous population health is to be improved. [ABSTRACT FROM AUTHOR]

Objective: To model population health impacts of dietary changes associated with the redevelopment of the UK food-based dietary guidelines (the ‘Eatwell Guide’). Method: Using multi-state lifetable methods, we modelled the impact of dietary changes on cardiovascular disease, diabetes and cancers over the lifetime of the current UK population. From this model, we determined change in life expectancy and disability-adjusted life years (DALYs) that could be averted. Results: Changing the average diet to that recommended in the new Eatwell Guide, without increasing total energy intake, could increase average life expectancy by 5.4 months (95% uncertainty interval: 4.7 to 6.2) for men and 4.0 months (3.4 to 4.6) for women; and avert 17.9 million (17.6 to 18.2) DALYs over the lifetime of the current population. A large proportion of the health benefits are from prevention of type 2 diabetes, with 440,000 (400,000 to 480,000) new cases prevented in men and 340,000 (310,000 to 370,000) new cases prevented in women, over the next ten years. Prevention of cardiovascular diseases and colorectal cancer is also large. However, if the diet recommended in the new Eatwell Guide is achieved with an accompanying increase in energy intake (and thus an increase in body mass index), around half the potential improvements in population health will not be realised. Conclusions: The dietary changes required to meet recommendations in the Eatwell Guide, which include eating more fruits and vegetables and less red and processed meats and dairy products, are large. However, the potential population health benefits are substantial. [ABSTRACT FROM AUTHOR]

Background: A "diet high in sodium" is the second most important dietary risk factor for health loss identified in the Global Burden of Disease Study 2013. We therefore aimed to model health gains and costs (savings) of salt reduction interventions related to salt substitution and maximum levels in bread, including by ethnicity and age. We also ranked these four interventions compared to eight other modelled interventions.Methods: A Markov macro-simulation model was used to estimate QALYs gained and net health system costs for four dietary sodium reduction interventions, discounted at 3 % per annum. The setting was New Zealand (NZ) (2.3 million adults, aged 35+ years) which has detailed individual-level administrative cost data.Results: The health gain was greatest for an intervention where most (59 %) of the sodium in processed foods was replaced by potassium and magnesium salts. This intervention gained 294,000 QALYs over the remaining lifetime of the cohort (95 % UI: 238,000 to 359,000; 0.13 QALY per 35+ year old). Such salt substitution also produced the highest net cost-savings of NZ$ 1.5 billion (US$ 1.0 billion) (95 % UI: NZ$ 1.1 to 2.0 billion). All interventions generated relatively larger per capita QALYs for men vs women and for the indigenous Māori population vs non-Māori (e.g., 0.16 vs 0.12 QALYs per adult for the 59 % salt substitution intervention). Of relevance to workforce productivity, in the first 10 years post-intervention, 22 % of the QALY gain was among those aged <65 years (and 37 % for those aged <70).Conclusions: The benefits are consistent with the international literature, with large health gains and cost savings possible from some, but not all, sodium reduction interventions. Health gain appears likely to occur among working-age adults and all interventions contributed to reducing health inequalities. [ABSTRACT FROM AUTHOR]

Abstract: Objective: The aim of this study is to provide an overview of interventions to reduce or prevent overweight or obesity and improve diet or physical activity. Methods: A review of meta-analyses and/or systematic reviews of these interventions in any setting or age group were conducted. Narrative systematic reviews were included for intervention categories with limited meta-analyses available. Summary measures including weighted mean difference, standardised mean difference, and I-squared, were examined. Results: A total of 60 meta-analyses and 23 systematic reviews met the inclusion criteria. Dietary interventions and multi-component interventions targeting overweight and obesity appeared to have the greatest effects, particularly in comparison with workplace or technology or internet-based interventions. Pharmaceutical and surgical interventions produced favourable results for specific population sub-groups (i.e. morbidly obese). Population-wide strategies such as policy interventions have not been widely analysed. The effectiveness of the interventions to assist in maintaining behaviour or weight change remains unclear. Conclusions: Various individually targeted interventions were shown to reduce body weight, although effect sizes were typically modest, and the durability of effects has been questioned. New approaches to evaluating population-based interventions, such as taxes and regulation, are recommended. Future research modelling the long-term effects of interventions across the lifespan would also be beneficial. [Copyright &y& Elsevier]

Objective To evaluate population health benefits and cost-effectiveness of interventions for reducing salt in the diet. Design Proportional multistate life-table modelling of cardiovascular disease and health sector cost outcomes over the lifetime of the Australian population in 2003. Interventions The current Australian programme of incentives to the food industry for moderate reduction of salt in processed foods; a government mandate of moderate salt limits in processed foods; dietary advice for everyone at increased risk of cardiovascular disease and dietary advice for those at high risk. Main Outcome Measures Costs measured in Australian dollars for the year 2003. Health outcomes measured in disability-adjusted life years (DALY) averted over the lifetime. Results Mandatory and voluntary reductions in the salt content of processed food are cost-saving interventions under all modelled scenarios of discounting, costing and cardiovascular disease risk reversal (dominant cost-effectiveness ratios). Dietary advice targeting individuals is not cost-effective under any of the modelled scenarios, even if directed at those with highest blood pressure risk only (best case median cost-effectiveness A$100000/DALY; 95% uncertainty interval A$64000/DALY to A$180000/DALY). Although the current programme that relies on voluntary action by the food industry is cost-effective, the population health benefits could be 20 times greater with government legislation on moderate salt limits in processed foods. Conclusions Programmes to encourage the food industry to reduce salt in processed foods are highly recommended for improving population health and reducing health sector spending in the long term, but regulatory action from government may be needed to achieve the potential of significant improvements in population health. [ABSTRACT FROM AUTHOR]