Investigating intervention components and their effectiveness in promoting environmentally sustainable diets: a systematic review.

Global food systems contribute 30% of global greenhouse gas emissions, threatening the global temperature targets of the Paris Agreement. Diets in high-income countries exceed the recommendations for animal-based foods, whereas consumption of fruits and vegetables is below recommendations. Shifting to a more plant-based diet can reduce up to 30% of greenhouse gas emissions from diet and also reduce risk of chronic disease. Interventions addressing sustainable dietary behaviour, defined by a shift in dietary patterns and food-waste practices, could therefore improve population and planetary health, but knowledge of the interventions that are likely to be most effective in changing sustainable dietary behaviour is so far limited. This systematic review aimed to investigate, classify, and assess the effectiveness of interventions that promote environmentally sustainable diets in high-income countries. We searched MEDLINE, Embase, PsycINFO, and Cumulative Index to Nursing and Allied Health Literature for randomised controlled trials and quasi-experimental trials published from inception until June 16, 2022, evaluating the effectiveness of any intervention promoting environmentally sustainable dietary behaviour. Studies were eligible for inclusion if they included adults and children from high-income countries (as defined by the World Bank classification) and used individual-level behaviour change interventions. Online choice experiments and studies reporting results on only change in fruit and vegetable consumption were excluded. Interventions were classified using the nine intervention functions of the behaviour change wheel. Data were extracted on number of participants, intervention characteristics, diet change (eg, meat consumption and fruit and vegetable intake), food waste, greenhouse gas emissions, and health outcomes. 13 studies were identified and included in the systematic review. Articles were from six different countries (ie, Canada, the USA, Germany, the UK, the Netherlands, Italy). Six of the nine intervention functions of the behaviour change wheel were used. Interventions using education had the most robust evidence base, whereas interventions using persuasion had the strongest effect on reducing meat consumption. Overall, interventions using education in combination with other factors were most successful. Five studies had high risk of bias, five had some concerns of bias, and three had low risk of bias. This systematic review provides insight into the effectiveness of behavioural interventions to meet health and climate change goals through promotion of environmentally sustainable diets. Evidence supports the use of multicomponent interventions through education, persuasion, and environmental restructuring to provide opportunity for change. Little high-quality research was available, and more robustly designed intervention studies are needed to inform future guidelines and policies.

Modelling impacts of a salt and sugar tax on hypothetical intra-category food substitutions, BMI and environmental footprints in the UK population.

PURPOSE: Taxes on unhealthy foods can help improve population health in the United Kingdom (UK), but the health effects of food substitutions resulting from these taxes are often unclear. We investigated the potential impacts of a salt and sugar tax on hypothetical intra-category food substitutions, cost, body-mass index (BMI), and environmental footprints. METHODS: Purchase panel data from Kantar (2017) were used to determine the most popular foods high in salt or sugar within eight 'salt-intensive'/'sugar-intensive' food categories. Within food categories, the most popular lower salt (≤ 1.5 g salt/100 g product) and lower sugar (≤ 22.5 g sugar/100 g product) substitutes were also identified. Hypothetical swaps between high salt/sugar foods and lower salt/sugar substitutes were explored, focusing on changes to cost, caloric intake and BMI, and environmental impacts in the UK population. RESULTS: The suggested intra-category substitutions were largely like-for-like and did not accrue an added overall cost to consumers. The substitutions reduced calorie intake by about 200 kcal/day and lowered the prevalence of overweight and obesity in the UK from approximately 60-65% to about 40-45%. The proposed food substitutions led to a total reduction of -2.7Mt of greenhouse gases, ∼ -500.000 ha of land, -0.5km3 of blue water, -12km3 of scarcity weighted water, ∼ -12.000t of phosphorus, and nearly - 14.000t of sulphur dioxide over one year for the UK population due to reductions in calorie intake. CONCLUSION: Food substitutions following a tax on salt and sugar could lead to significant benefits for health and the environment, without necessarily resulting in major changes to people's expenditure on familiar salty and sugary snacks.

Addressing future food demand in The Gambia: can increased crop productivity and climate change adaptation close the supply-demand gap?

With rising demand for food and the threats posed by climate change, The Gambia faces significant challenges in ensuring sufficient and nutritious food for its population. To address these challenges, there is a need to increase domestic food production while limiting deforestation and land degradation. In this study, we modified the FABLE Calculator, a food and land-use system model, to focus on The Gambia to simulate scenarios for future food demand and increasing domestic food production. We considered the impacts of climate change on crops, the adoption of climate change adaptation techniques, as well as the potential of enhanced fertiliser use and irrigation to boost crop productivity, and assessed whether these measures would be sufficient to meet the projected increase in food demand. Our results indicate that domestic food production on existing cropland will not be sufficient to meet national food demand by 2050, leading to a significant supply-demand gap. However, investments in fertiliser availability and the development of sustainable irrigation infrastructure, coupled with climate change adaptation strategies like the adoption of climate-resilient crop varieties and optimised planting dates, could halve this gap. Addressing the remaining gap will require additional strategies, such as increasing imports, expanding cropland, or prioritising the production of domestic food crops over export crops. Given the critical role imports play in The Gambia's food supply, it is essential to ensure a robust flow of food imports by diversifying partners and addressing regional trade barriers. Our study highlights the urgent need for sustained investment and policy support to enhance domestic food production and food imports to secure sufficient and healthy food supplies amidst growing demand and climate change challenges. Supplementary Information: The online version contains supplementary material available at 10.1007/s12571-024-01444-1.

Mapping the evidence of novel plant-based foods: a systematic review of nutritional, health, and environmental impacts in high-income countries.

CONTEXT: Shifting from current dietary patterns to diets rich in plant-based (PB) foods and lower in animal-based foods (ABFs) is generally regarded as a suitable strategy to improve nutritional health and reduce environmental impacts. Despite the recent growth in supply of and demand for novel plant-based foods (NPBFs), a comprehensive overview is lacking. OBJECTIVES: This review provides a synthesis of available evidence, highlights challenges, and informs public health and environmental strategies for purposeful political decision-making by systematically searching, analyzing, and summarizing the available literature. DATA SOURCES: Five peer-reviewed databases and grey literature sources were rigorously searched for publications. DATA EXTRACTION: Study characteristics meeting the inclusion criteria regarding NPBF nutrient composition and health and environmental outcomes in high-income countries were extracted. DATA ANALYSIS: Fifty-seven peer-reviewed and 36 grey literature sources were identified; these were published in 2016-2022. NPBFs typically have substantially lower environmental impacts than ABFs, but the nutritional contents are complex and vary considerably across brands, product type, and main primary ingredient. In the limited evidence on the health impacts, shifts from ABFs to PB meats were associated with positive health outcomes. However, results were mixed for PB drinks, with links to micronutrient deficiencies. CONCLUSION: If carefully selected, certain NPBFs have the potential to be healthier and nutrient-rich alternatives to ABFs and typically have smaller environmental footprints. More disaggregated categorization of various types of NPBFs would be a helpful step in guiding consumers and key stakeholders to make informed decisions. To enable informed policymaking on the inclusion of NPBFs in dietary transitions as part of a wider net-zero and health strategy, future priorities should include nutritional food standards, labelling, and subdivisions or categorizations of NPBFs, as well as short- and long-term health studies evaluating dietary shifts from ABFs to NPBFs and standardized environmental impact assessments, ideally from independent funders.

An umbrella review of health co-benefits from actions to reduce greenhouse gas emissions.

BACKGROUND: There have been many modelled studies of potential health co-benefits from actions to reduce greenhouse gas emissions, but so far there have been no large-scale attempts to compare the magnitude of health and climate effects across sectors, countries, and study designs. METHODS: As part of the Pathfinder Initiative project an umbrella review of studies was done, and 26 previous reviews were identified with 57 primary studies included. Studies included in the review were required to have quantified changes in greenhouse gas emissions and health effects (or risk factors) from defined actions to reduce climate effects. Study data were extracted and harmonised by standardising impact measures per 100 000 of the national population (or urban population for city-level actions), averaging effects over a 1-year period and aggregating actions into their respective sectors by use of a predefined framework. FINDINGS: From 200 mitigation actions, the majority were in the agriculture, forestry, and land use sector (103 actions [52%]), followed by the transport sector (43 actions [22%]). The largest effects on greenhouse gas emissions were seen from actions in the energy sector, and these actions also had substantial health co-benefits in lower middle-income countries, although benefits were smaller in high-income settings. The greatest health benefits were seen from actions to change diets and introduce clean cookstoves. The major pathways to health were through reduced air pollution, healthier diets, and increased physical activity from switching to active travel modes. Effect sizes tended to be larger from national modelling studies and smaller from localised or implemented actions. INTERPRETATION: The potential co-benefits to health from actions to reduce climate change are large, but most evidence still comes from modelling studies and from high-income and middle-income countries. There are also major context-dependent differences in the magnitude of effects found, so actions need to be tailored to the local context and careful attention needs to be paid to potential trade-offs and spillover effects. FUNDING: The Wellcome Trust and the Oak Foundation.

Barriers to Adopting a Plant-Based Diet in High-Income Countries: A Systematic Review.

Adopting a plant-based diet (PBD) has been shown to reduce the risk of developing certain diseases and is linked to environmental benefits. This review synthesises the evidence on the barriers adults aged 18 to 65 living in high-income countries (HIC) may experience when adopting a PBD. A systematic literature review was conducted using four search databases: Medline, Embase, Global Health, and Web of Science. Barriers were mapped to behaviour change strategies using the COM-B model. Ten studies were included in the final review, including 1740 participants. Five were qualitative, four were cross-sectional, and one was a pre- and-post-intervention study. In total, 40 barriers were identified and synthesised into 11 themes: financial, lack of knowledge, emotional, health, convenience, social, enjoyment of meat, environmental, accessibility, personal ability, and media. Of the 40 barriers, nutritional intake/requirements (categorised into the "health" theme) had the most evidence. This barrier encompassed concerns around being able to meet nutritional needs if an individual were to adopt a PBD. Habits (in the "personal ability" theme), which included established eating habits and habitual behaviours relating to animal-source foods, had the second most evidence alongside the barrier of not knowing what to eat as part of a PBD (in the "lack of knowledge" theme). Education interventions and communication/marketing policies were the behaviour change mechanisms mapped onto these barriers. Future interventions should focus on informing individuals about what to consume as part of a nutritionally balanced PBD and facilitating habitual dietary change.

Dietary patterns in North and South India: a comparison with EAT-Lancet dietary recommendations.

BACKGROUND: Environmentally sustainable diets are represented in the EAT-Lancet recommendations developed by the Lancet Commission on Planetary Health in 2019. Very few studies have compared Indian diets with the EAT-Lancet recommendations. The present study performed such a comparison using primary dietary consumption data from adults in north and south India. METHODS: Data from 8762 adults (52.4 ± 11.7 years) residing in Sonipat and Vizag India were collected on sociodemographic characteristics, wealth index (household assets) and dietary intake (food frequency questionnaire: nine food groups). The quantity consumed and energy from each food group was compared with the EAT-Lancet recommendations. We investigated the likelihood of deficit or excess in consumption compared to the EAT-Lancet recommendations by different sociodemographic factors. RESULTS: Half of the participants were women and half resided in rural areas. Vegetables and fruits were consumed in lower quantity, whereas dairy and added fats were consumed in higher quantity than recommended by the EAT-Lancet recommendations. For whole grains, female gender and poorest wealth index were the factors associated with deficit or no consumption, whereas, for vegetables and fruits, it was poorest wealth index and residence in rural areas (p < 0.05, all). Rural residence and poorest wealth index were associated with excess consumption of dairy and added fats (p < 0.05, all). CONCLUSIONS: The diets of the study participants were mainly plant-based, and high in dairy but lacking in nutrient-rich foods such as vegetables and fruits. Appropriate policy actions for making healthy sustainable diets and micronutrient-rich foods available and affordable to all with a particular focus on the poor and rural populations are warranted.

Socio-economic and food system drivers of nutrition and health transitions in The Gambia from 1990 to 2017.

In common with many nations undergoing a nutrition transition, micronutrient deficiencies, undernutrition and overnutrition coexist in The Gambia. Addressing these challenges simultaneously would require transformational changes in the country's food system. However, the evidence base that would enable informed decision-making in the Gambian food system has been scant, despite several sources of routinely-collected data being available. This descriptive study brings together data from four open-access global databases on food supply, political, economic, and demographic variables, and nutrition and health between 1990 and 2017 to study potential leverage points for improvement in the food system. It compares trends in food supply and nutritional outcomes in The Gambia against regional and global averages, and identifies potential drivers taken from a food systems framework. The data show that, over the past three decades, total energy supply has increased, and obesity is rising quickly, but iron deficiency persists in a proportion of the population. Overall diet composition is poor, with lower availability of fruit and vegetables and higher supply of sugar and oils compared to regional and global averages. Domestic production is low for most food groups and so a high dependence on imports from other countries bridges the gap in terms of energy supply. Measures of economic development, particularly GDP, were positively related with supply of cereals and animal source foods over time, but no such relationship was observed with fruit and vegetable supply. Food system policy to improve nutrition and health outcomes in The Gambia needs to focus on improving the diversity of food supply - especially fruit and vegetables - and maximizing national domestic production to reduce reliance on food imports. The use of open-source global datasets can be feasible in exploring food system characteristics and trends at the national level and could be applied in other contexts.

Snacking Behavior and Association with Metabolic Risk Factors in Adults from North and South India.

BACKGROUND: Snacks are increasingly contributing to daily diets around the world. Studies from high-income countries have demonstrated the link between snack consumption and metabolic risk factors, but there are very few studies from low- and middle-income countries. OBJECTIVES: The objective of this study was to assess snack behavior and its associations with metabolic risk factors in Indian adults. METHODS: Adults from the UDAY study (October 2018-February 2019, n = 8762) from rural and urban Sonipat (North) and Vizag (South) India were studied for snack consumption (food frequency questionnaire), demographic factors, including age, sex, etc. and metabolic risk factors, including BMI, waist circumference, fat percentage, plasma glucose, and blood pressure. We compared snack consumption by categories of sociodemographic factors (Mann-Whitney U test, Kruskal-Wallis test) and studied the likelihood for metabolic risk (logistic regression analysis). RESULTS: Half of the study participants were women and resided in rural locations. Savory snacks were the most preferred; 50% of the participants consumed them 3-5 times/wk. Participants preferred to purchase out-of-home prepared snacks and eat them at home (86.6%) while watching television (69.4%) or with family/friends (49.3%). The reasons for snacking were hunger, craving, liking, and availability. Snack consumption was higher in Vizag (56.6%) than in Sonipat (43.4%), among women (55.5%) than men (44.5%), and the wealthiest; it was similar in rural-urban locations. Frequent consumers of snacks had 2 times higher likelihood for having obesity (OR: 2.22; 95% CI: 1.51, 3.27) central obesity (OR: 2.35; 95% CI: 1.60, 3.45), and higher fat percentage (OR: 1.92; 95% CI: 1.31, 2.82) and higher fasting glucose levels (r=0.12 (0.07-0.18) than consumers who consumed snacks rarely (all P ≤ 0.05). CONCLUSIONS: Snack (savory and sweet) consumption was high among adults from sexes in both urban and rural locations of north and south India. This was associated with higher risk of obesity. There is a need to improve the food environment by promoting policies for ensuring healthier food options to reduce snacking and associated metabolic risk.

Impact on mortality of pathways to net zero greenhouse gas emissions in England and Wales: a multisectoral modelling study.

BACKGROUND: The UK is legally committed to reduce its greenhouse gas emissions to net zero by 2050. We aimed to understand the potential impact on population health of two pathways for achieving this target through the integrated effects of six actions in four sectors. METHODS: In this multisectoral modelling study we assessed the impact on population health in England and Wales of six policy actions relating to electricity generation, transport, home energy, active travel, and diets relative to a baseline scenario in which climate actions, exposures, and behaviours were held constant at 2020 levels under two scenarios: the UK Climate Change Committee's Balanced Pathway of technological and behavioural measures; and its Widespread Engagement Pathway, which assumes more substantial changes to consumer behaviours. We quantified the impacts of each policy action on mortality using a life table comprising all exposures, behaviours, and health outcomes in a single model. FINDINGS: Both scenarios are predicted to result in substantial reductions in mortality by 2050. The Widespread Engagement Pathway achieves a slightly greater reduction in outdoor fine particulate matter air pollution of 3·2 µg/m3 (33%) and, under assumptions of appropriate ventilation, a greater improvement in indoor air pollution (a decrease in indoor-generated fine particulate matter from 9·4 µg/m3 to 4·6 µg/m3) and winter temperatures (increasing from 17·8°C to 18·1°C), as well as appreciably greater changes in levels of active travel (27% increase in metabolic equivalent hours per week of walking and cycling) by 2050. Additionally, the greater reduction in red meat consumption (50% compared with 35% under the Balanced Pathway) by 2050 results in greater consumption of fruits (17-18 g/day), vegetables (22-23 g/day), and legumes (5-7 g/day). Combined actions under the Balanced Pathway result in more than 2 million cumulative life-years gained over 2021-50; the estimated gain under the Widespread Engagement Pathway is greater, corresponding to nearly 2·5 million life-years gained by 2050 and 13·7 million life-years gained by 2100. INTERPRETATION: Reaching net zero greenhouse gas emissions is likely to lead to substantial benefits for public health in England and Wales, with the cumulative net benefits being correspondingly greater with a pathway that entails faster and more ambitious changes, especially in physical activity and diets. FUNDING: National Institute for Health Research and the Wellcome Trust.

Growing health: global linkages between patterns of food supply, sustainability, and vulnerability to climate change.

Global food systems are developing rapidly, and have resulted in a large burden of disease and a high proportion of environmental resource use. We combined global data sources on food supply and trade, environmental footprints, burdens of disease, and vulnerability to climate change to explore patterns from 1990 to 2017. Four distinct patterns of food supply (animal sources and sugar, vegetables and nuts, starchy roots and fruits, and seafood and oils) were matched to health and environmental risks. The animal sources and sugar pattern was found to have the greatest environmental footprint and to be associated with a greater burden of chronic disease than any other pattern, although it was also associated with lower undernutrition. This pattern is globally predominant, but has begun to decrease in higher income countries. Countries where this pattern is predominant are generally among the least susceptible to climate change, whereas more susceptible countries tend to have more sustainable patterns of food supply. More countries that are susceptible to climate change are increasingly exporting a larger proportion than before of their cereals, fruit, and vegetables globally, which will lead to increased risks in global food security. To increase resilience to future shocks, dietary change towards more sustainable patterns should accelerate in high-income countries, and the food systems of the most susceptible countries should be protected.

Adherence to EAT-Lancet dietary recommendations for health and sustainability in the Gambia.

Facilitating dietary change is pivotal to improving population health, increasing food system resilience, and minimizing adverse impacts on the environment, but assessment of the current 'status-quo' and identification of bottlenecks for improvement has been lacking to date. We assessed deviation of the Gambian diet from the EAT-Lancet guidelines for healthy and sustainable diets and identified leverage points to improve nutritional and planetary health. We analysed the 2015/16 Gambian Integrated Household Survey dataset comprising food consumption data from 12 713 households. Consumption of different food groups was compared against the EAT-Lancet reference diet targets to assess deviation from the guidelines. We computed a 'sustainable and healthy diet index (SHDI)' based on deviation of different food groups from the EAT-Lancet recommendations and modelled the socio-economic and geographic determinants of households that achieved higher scores on this index, using multivariable mixed effects regression. The average Gambian diet had very low adherence to EAT-Lancet recommendations. The diet was dominated by refined grains and added sugars which exceeded the recommendations. SHDI scores for nutritionally important food groups such as fruits, vegetables, nuts, dairy, poultry, and beef and lamb were low. Household characteristics associated with higher SHDI scores included: being a female-headed household, having a relatively small household size, having a schooled head of the household, having a high wealth index, and residing in an urban settlement. Furthermore, diets reported in the dry season and households with high crop production diversity showed increased adherence to the targets. While average Gambian diets include lower amounts of food groups with harmful environmental footprint, they are also inadequate in healthy food groups and are high in sugar. There are opportunities to improve diets without increasing their environmental footprint by focusing on the substitution of refined grains by wholegrains, reducing sugar and increasing fruit and vegetables consumption.

Processed foods purchase profiles in urban India in 2013 and 2016: a cluster and multivariate analysis.

OBJECTIVES: Sales of ultraprocessed foods (UPFs) and beverages are rising in low-income and middle-income countries. Such foods are often linked with weight gain, obesity, type 2 diabetes and hypertension-diseases that are on the rise in India. This paper analysed patterns in purchases of processed and UPF by urban Indian households. SETTING: Panel data from Kantar -Worldpanel Division, India for 2013 and 2016. PARTICIPANTS: 58 878 urban Indian households. METHODS: We used K-mean partition clustering and multivariate regression to analyse patterns in processed food (PF) and UPF purchase for urban India. RESULTS: Three-quarters of urban Indian households purchased over ten PF groups. Mean per person annual PF purchase was 150 kg. UPF purchase was low at 6.4 kg in 2016 but had grown by 6% since 2013. Cluster analysis identified three patterns of consumption, characterised by low (54% of the households in 2016), medium (36%) and high (10%) PF purchase quantities. High cluster households purchased over three times as much PFs and UPF as the low cluster households. Notably, salt purchases were persistently high across clusters in both years (>3.3 kg), while sweet snack and ready-to-eat food purchases grew consistently in all clusters between 2013 and 2016. A positive and significant association was found between household purchases of UPF and their socioeconomic status as well as ownership of durables, such as refrigerator, colour television and washing machine (all p<0.001). Spatial characteristics including size of town (p<0.05) in which the household is located were also positively associated with the purchase of UPF. CONCLUSION: Results suggest the need for tailored regional and city level interventions to curb the low but growing purchase of UPF. New data on obesity and rise of non-communicable diseases, the results are concerning given the links between lifestyle changes and the speed of urbanisation in Indian cities.

Changes in Climate Vulnerability and Projected Water Stress of The Gambia's Food Supply Between 1988 and 2018: Trading With Trade-Offs.

Background: The coexistence of under- and overnutrition is of increasing public health concern in The Gambia. Fruits, vegetables and pulses are essential to healthy and sustainable diets, preventing micronutrient deficiencies and non-communicable diseases, while cereals significantly contribute to energy intake. However, environmental changes are predicted to intensify, reducing future yields of these crops if agricultural productivity and resilience are not improved. The Gambia is highly climate-vulnerable and import-dependent, but the extent of its reliance on other climate-vulnerable countries for its supply of nutritionally important crops is currently unknown. Methods: We used United Nations Food and Agriculture Organization data, with novel origin-tracing algorithms applied, to analyse The Gambia's supply of cereals, fruits, vegetables and pulses between 1988 and 2018. The climate vulnerability of countries was assessed using Notre Dame Global Adaptation Initiative (ND-GAIN) index scores, and projected water stress (2040) assessed using World Resources Institute (WRI) scores. Multilevel generalized linear mixed-effects models were used to identify changes in the overall climate vulnerability and projected water stress of supply. Results: Between 1988 and 2018, The Gambia's supply of cereals, fruits, vegetables and pulses diversified, with the proportion domestically produced falling (Cereals: 61.4%-27.7%; Fruits: 93.0%-55.7%; Vegetables: 24.6%-16.3%; Pulses: 100.0%-76.0%). The weighted-average ND-GAIN scores improved (indicating less climate vulnerability) for supply of all crops except cereals, but the weighted-average WRI score for supply deteriorated (indicating increased projected water stress) for all crops except vegetables. When just considering imports, weighted-average ND-GAIN scores deteriorated for fruits and cereals while showing no significant change for other food groups, and the WRI score deteriorated for cereals only. Conclusions: Despite some notable improvements in the environmental vulnerability of The Gambia's supply of nutritionally important crops (particularly vegetables), considerable, and in some cases increasing, proportions of their supply are produced in countries that are vulnerable to climate change and future water stress. This may have implications for the availability, affordability, and hence consumption of these crops in The Gambia, ultimately exacerbating existing nutritional challenges. Exploring the options to strengthen supply resilience-such as altering trade patterns, agricultural techniques and diets-should be prioritized.

Nitrate and nitrite contamination in drinking water and cancer risk: A systematic review with meta-analysis.

BACKGROUND: Pollution of water sources, largely from wide-scale agricultural fertilizer use has resulted in nitrate and nitrite contamination of drinking water. The effects on human health of raised nitrate and nitrite levels in drinking water are currently unclear. OBJECTIVES: We conducted a systematic review of peer-reviewed literature on the association of nitrate and nitrite in drinking water with human health with a specific focus on cancer. METHODS: We searched eight databases from 1 January 1990 until 28 February 2021. Meta-analyses were conducted when studies had the same exposure metric and outcome. RESULTS: Of 9835 studies identified in the literature search, we found 111 studies reporting health outcomes, 60 of which reported cancer outcomes (38 case-control studies; 12 cohort studies; 10 other study designs). Most studies were set in the USA (24), Europe (20) and Taiwan (14), with only 3 studies from low and middle-income countries. Nitrate exposure in water (59 studies) was more commonly investigated than nitrite exposure (4 studies). Colorectal (15 studies) and gastric (13 studies) cancers were the most reported. In meta-analyses (4 studies) we identified a positive association of nitrate exposure with gastric cancer, OR = 1.91 (95%CI = 1.09-3.33) per 10 mg/L increment in nitrate ion. We found no association of nitrate exposure with colorectal cancer (10 studies; OR = 1.02 [95%CI = 0.96-1.08]) or cancers at any other site. CONCLUSIONS: We identified an association of nitrate in drinking water with gastric cancer but with no other cancer site. There is currently a paucity of robust studies from settings with high levels nitrate pollution in drinking water. Research into this area will be valuable to ascertain the true health burden of nitrate contamination of water and the need for public policies to protect human health.

Quantifying the effectiveness and health co-benefits of climate change mitigation actions across sectors: a protocol for an umbrella review.

BACKGROUND: Effective and rapid actions are required to achieve global goals for climate change mitigation, and there is an opportunity to ensure that the actions taken are also positive for human health. However, little is known about the relative magnitude of the health co-benefits that can be achieved from mitigation actions, so robust and comprehensive syntheses of the evidence on the nature and effects of relevant actions are required. This paper presents a protocol for an interdisciplinary and cross-sectoral umbrella review of systematic reviews, synthesising modelled and empirical evidence on such actions. METHODS: Nine bibliographic databases will be searched, capturing literature across a wide range of disciplines and sectors. Unique records retrieved by the searches will be screened by two independent reviewers. The quality of all the included systematic reviews will be assessed using A MeaSurement Tool to Assess Systematic Reviews (AMSTAR) 2 critical appraisal tool. Data will be extracted on methodological and thematic characteristics of the reviews, nature of the actions, and their effects on greenhouse gas emission reduction, health, and its determinants, as well as any other reported effects and interactions across different actions. RESULTS: Narrative and quantitative synthesis methods will be used to create a typology of relevant actions, map pathways to their impacts on health, compare the magnitude of health and greenhouse gas (GHG) emission reduction impacts by selected characteristics of the actions and the nature of the evidence, as well as to identify gaps in evidence syntheses. CONCLUSION: This review will identify the most effective actions for global climate change mitigation and health based on the best available scientific evidence.   This protocol has been registered in PROSPERO, Reg No.: CRD42021239292.

The role of plant-based alternative foods in sustainable and healthy food systems: Consumption trends in the UK.

A global transformation towards sustainable food systems is crucial for delivering on climate change mitigation targets worldwide. In high- and middle-income settings, plant-based meat and dairy alternatives present potential substitutes for animal sourced foods, and a pathway to transition to more sustainable diets. We examined plant-based alternative foods (PBAF) consumption trends in the UK by analysing repeated cross-sectional food consumption data from the National Diet and Nutrition Survey 2008-2019. Dietary data for 15,655 individuals aged 1.5 years and over were analysed to assess aggregate change in intake of PBAF and six other food groups that play a role in transformative dietary change. Characteristics associated with consumption of PBAF were explored using logistic regression, and consumption patterns in high and low meat consumers were explored by examining intake of potential animal product substitute food groups. The proportion of individuals reporting consumption of any PBAFs increased from 6.7% in 2008-2011, to 13.1% in 2017-2019 (p < 0.01). Compared to 2008-2011 PBAF consumption rose by 115% in 2017-2019 (p < 0.01). Females were 46% more likely than males to report consumption of PBAF (p < 0.01). Millennials (age 24-39 years) were the most likely generation to report PBAF consumption (p < 0.01 compared to generation Z (age 11-23 years) and traditionalists (age 75+ years)), as were individuals of the highest income tertile (p < 0.01). Among "low meat consumers", PBAF consumption was on average higher than "high meat consumers" (18.6 g versus 4.8 g PBAF per day, p < 0.01). Our results support the hypothesis of a pivotal role of PBAF in the transition towards sustainable food systems in the UK, by demonstrating they are becoming increasingly popular among UK consumers. This highlights the urgent need to assess in detail the environmental and health impacts of large scale and population-wide consumption of PBAF in comparison to their animal-based equivalents.