Effect of environmental change on yield and quality of fruits and vegetables: two systematic reviews and projections of possible health effects

Background: Environmental changes—including climatic change, land degradation, water scarcity, and biodiversity loss—threaten agricultural production and quality and pose challenges to global food security. Most research in this area has focused on staple crop yields. By contrast, relatively little attention has been given to fruits and vegetables that are important for nutrition and health, including for the prevention of non-communicable diseases. In this study, we review the evidence of the effects of environmental change on the yield and quality of fruits and vegetables, and assess possible implications for nutrition and health outcomes. Methods: We undertook two systematic reviews of the global published literature on the effect of environmental change on (1) yields and (2) nutritional quality of fruits and vegetables. We evaluated the evidence for 12 different environmental stressors: here we focus on atmospheric temperature and CO2 concentrations, and precipitation patterns. Data were analysed from two study types: greenhouse experiments and model simulations. We used the review findings to assess the possible health consequences of changed availability and quality of fruits and vegetables in low-income, middle-income, and high-income settings. Findings: Although findings varied between crop type and climatic zones, we did identify some consistent trends. In tropical countries, there were largely adverse effect on yield of increased temperature and changing precipitation patterns, although in more temperate zones some beneficial effects on yield were reported. Increased CO2 concentration had a predominantly positive effect on yield. The effects of (moderate) increases in temperature and reduced precipitation on nutritional quality of fruits and vegetables were mostly positive with higher vitamin, mineral and soluble solid contents measured in many crops, largely as a result of plant stress responses. Increased atmospheric CO2 concentrations had predominantly negative effects on nutritional quality of fruits and vegetables. Because most studies investigated one change, the combined and interactive effects of all environmental stressors remain unclear. Adverse health implications, including the potential for nutrient deficiencies and related chronic diseases were estimated to be largest in areas characterised by high vulnerability to environmental change and high rates of poverty and food insecurity, as well as areas that are highly dependent on local markets. Interpretation: Our reviews identified effects of environmental change on yields and quality of fruits and vegetables that might pose threats to population health, especially in areas vulnerable to climate-change and food insecurity: directly through reduced consumption, and indirectly through income pathways that might result in restricted household dietary energy intake and dietary diversity. To obtain more precise estimates of the change in burden of disease and mortality attributable to affected yields and quality of fruits and vegetables, further research is needed on farmers' and consumers' adaptation and substitution strategies. Furthermore, the combined effect of multiple environmental stressors on fruit and vegetable yield and quality should be further quantified. These data would allow development of future scenarios, based on projected environmental changes and simulations of human behaviour change. Funding: Wellcome Trust

Projected health effects of realistic dietary changes to address freshwater constraints in India: a modelling study

Background: The availability of freshwater for irrigation in the Indian agricultural sector is expected to decline over the coming decades. This might have implications for food production in India, with subsequent effects on diets and health. We identify realistic and healthy dietary changes that could enhance the resilience of the Indian food system to future decreases in water availability. Methods: In this modelling study, we optimised typical dietary patterns in an Indian population sample to meet projected decreases in the availability of water per person for irrigation (blue water footprint) due to population growth (to 2025 and 2050). The optimised diets met nutritional guidelines and minimised deviation from existing patterns. Resulting changes in life-years lost due to coronary heart disease, stroke, diabetes, and cancers were modelled using life tables, and changes in greenhouse gas emissions associated with the production of diets were estimated. The primary outcomes of the model were changes in life-years per 100 000 total population over 40 years (to 2050). Findings: The optimised diets had up to 30% lower blue water footprints and generally contained lower amounts of wheat, dairy, and poultry, and increased amounts of legumes. In the 2050 scenario, adoption of these diets would on average result in 6800 life-years gained per 100 000 total population (95% CI 1600–13 100) over 40 years. The dietary changes were accompanied by reductions in greenhouse gas emissions. The magnitude of the health and environmental effects varied between dietary patterns. Interpretation: Modest changes in diets could help to address projected reductions in the availability of freshwater for irrigation in India. These dietary changes could also simultaneously reduce diet-related greenhouse gas emissions and improve diet-related health outcomes. Funding: Wellcome Trust