Composite dietary antioxidants reduce mortality risk in obesity by alleviating sarcopenia: a mediation analysis of the NHANES cohort

Background Obesity is a major health issue associated with higher mortality. The Composite Dietary Antioxidant Index (CDAI), which measures overall antioxidant intake, may influence this risk, but its role in obese individuals is unclear. Sarcopenia, a common condition in obesity, might be a key mediator. Methods This study included 8,900 obese participants (BMI ≥ 30) from the National Health and Nutrition Examination Survey (NHANES). CDAI was calculated based on dietary intakes of vitamin A, vitamin C, vitamin E, carotenoids, zinc, and selenium. The primary outcome was all-cause mortality, and the secondary outcome was premature death. Weighted Cox regression models were used to analyze the association between CDAI and mortality risk, along with subgroup analyses. Mediation analysis was further conducted to examine the role of sarcopenia in the relationship between CDAI and mortality. Results A nonlinear relationship was observed. Increasing CDAI was linked to a significantly lower risk of all-cause and premature mortality at lower intake levels, with the effect plateauing at higher intakes. After adjustment for confounders, higher CDAI remained protective. Sarcopenia was found to partially mediate this association, accounting for 5.20% of the total effect. Conclusion In an obese population, higher CDAI is associated with reduced risks of all-cause and premature mortality, and this relationship is partially mediated through sarcopenia.