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-h 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 6 socioeconomic 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, whereas 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% confidence interval (CI): 147 g/d, 153 g/d] to 166 g/d [95% CI: 162 g/d, 171 g/d], +11%} than in females [101 g/d (95% CI: 98 g/d, 103 g/d) to 107 g/d (95% CI: 104 g/d, 109 g/d), +6%]. Across socioeconomic profiles, changes shared similar directions, but some trends were more marked, notably for alcoholic beverages among employees (95% CI: 114 g/d, 130 g/d; +14%) and sugar-sweetened beverages in young (95% CI: 56 g/d, 72 g/d; +29%). Consumption of fruits increased more modestly in the young (95% CI: 227 g/d, 248 g/d; +9%) than in employees (95% CI: 194 g/d, 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.