Inverse associations of dietary and circulating carotenoids with body mass index in adults: A mediation analysis from a large population-based cohort study

BackgroundThe high prevalence of overweight/obesity and low fruit and vegetable consumption in the United States underscores the need to better understand the role of carotenoids in body mass index (BMI) management. While carotenoids have anti-obesity mechanisms, their influence on BMI remains inconclusive.AimThis study aimed to examine the association between total dietary carotenoid intake and the risk of abnormal BMI (≥25 kg/m²), and to validate this relationship using serum carotenoid levels.MethodsWe analyzed data from 13,449 adults participating in the National Health and Nutrition Examination Survey (NHANES) 2011-2018 cycles, applying weighted multi-variable logistic regression, restricted cubic spline (RCS) modeling, and mediation analysis.ResultsIndividuals with abnormal BMI-representing 73.3% of the cohort-had significantly lower levels of both dietary and serum carotenoids. After full adjustment, those in the highest quintile of dietary carotenoid intake had a lower risk of abnormal BMI compared to those in the lowest quintile (odds ratio: 0.798; 95% confidence interval: 0.678-0.939), a pattern consistent with serum carotenoid levels. RCS analysis revealed a significant non-linear association, with protective effects observed above inflection points of 12.37 μg/kg/day for dietary intake and 0.21 μmol/L for serum concentrations. Mediation analysis further indicated that serum carotenoids accounted for approximately 64.2% of the total effect of dietary intake on BMI.ConclusionThese findings suggest that higher carotenoid intake may be associated with a lower risk of abnormal BMI, potentially mediated through circulating carotenoids. Promoting carotenoid-rich diets may offer a promising strategy for obesity prevention, though further research is warranted to refine intake recommendations.