Association of composite dietary antioxidant index (CDAI) with all-cause mortality in adults with abdominal obesity

Introduction Abdominal obesity significantly increases the risk of all-cause mortality, and the oxidative stress mediated by visceral fat is considered a key driving mechanism. Currently, epidemiological studies on the comprehensive dietary antioxidant index (CDAI) and mortality outcomes mainly target ordinary adults, diabetic patients, or hypertensive patients. To date, there are few specialized studies on this association in adults with abdominal obesity, resulting in a lack of evidence supporting precise nutritional prevention strategies for this high-risk population.Theory This study is based on the fat oxidative stress theory. We used the CDAI as the exposure indicator, which is an index that integrates six key dietary antioxidant micronutrients. Further, a nonlinear statistical model was applied to examine the potential threshold effect between antioxidant intake levels and mortality risk.Methods Data were derived from 14,290 eligible participants in the NHANES cohort from 2003 to 2016, with a median follow-up time of 100 months. Cox proportional hazards regression with survey-weighted, Kaplan-Meier survival analysis, and restricted cubic spline models were conducted. In all statistical analyses, a series of demographic, behavioral, and clinical confounding factors were adjusted.Results During the follow-up period, a total of 1,821 deaths were recorded. Higher CDAI values were associated with higher survival probabilities. We identified a threshold of -2.709; beyond this critical point, the protective survival benefit of CDAI disappeared. The slight increase in mortality risk observed at extremely high CDAI levels may be due to the limited sample size within the extreme range rather than intrinsic adverse biological effects.Discussion These findings provide new population-based epidemiological evidence for adults with abdominal obesity. Limitations include reliance on a single 24-hour dietary recall and the possibility of residual confounding factors. These results support dietary guidance recommendations for adults with abdominal obesity, namely, balanced intake of dietary antioxidants. Longitudinal prospective cohort studies are needed to verify the causal nature of this relationship.