The relationship between food intake and outdoor temperature in a longitudinal study: a public health perspective in the context of global warming

BACKGROUND: Climate change affects human health and nutrition. Rising temperatures may significantly impact diets, but research on their influence on dietary habits in large populations remains limited. OBJECTIVES: We aimed to study the link between outdoor temperature and energy-adjusted food consumption across profiles in a longitudinal study. METHODS: This study included 100,851 participants from the NutriNet-Santé study (2009-2023) with 1,716,046 24-hour dietary records linked to daily maximum outdoor temperature at the residence, from the nearest Météo-France station. Associations were analyzed using linear mixed models with interactions tested for sex and six socio-economic profiles (employees, privileged, intermediate, young, disadvantaged, and retirees) derived from clustering. RESULTS: Across all subgroups, higher outdoor temperature was associated with higher consumption of fruits, vegetables, processed meats, sweet products, water, alcoholic beverages, and sugar-sweetened beverages, while consumption of red meat, pulses, and dairy products decreased. From 25°C to 35°C, the increase in alcohol consumption with temperature was more pronounced in males (150 g/d (95%CI 147, 153) to 166 g/d (95%CI 162, 171), +11%) than in females (101 g/d (95%CI 98, 103) to 107 g/d (95%CI 104, 109), +6%). Across socio-economic profiles, changes shared similar directions but some trends were more marked, notably for alcoholic beverages among employees (114 g/d to 130 g/d, +14%) and sugar-sweetened beverages in young (56 g/d to 72 g/d, +29%). Consumption of fruits increased more modestly in the young (227 g/d to 248 g/d, +9%) than in employees (194 g/d to 227 g/d, +17%). These changes, although variable in magnitude, were not accompanied by substantial modifications in energy intake or overall diet quality scores. CONCLUSIONS: These results emphasize the importance of targeted prevention messages when temperatures exceed 25°C, especially concerning alcoholic and sugar-sweetened beverages, and offer insight into potential long-term food consumption patterns (beyond seasonal changes) in the context of global warming.