Composite dietary antioxidant index and obesity among U.S. adults in NHANES 2007-2018

Antioxidant-rich diets serve as protective factors in preventing obesity. The composite dietary antioxidant index (CDAI) represents a novel, comprehensive metric for assessing the antioxidant capacity of diets. Our objective is to investigate the relationship between the CDAI and obesity prevalence among adults in the United States. Dietary and anthropometric information about adults aged 20 years and older were obtained from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. The CDAI was derived from six dietary antioxidants. Obesity is defined as a body mass index (BMI, kg/m²) ≥ 30 kg/m², and abdominal obesity as a waist circumference (WC, cm) ≥ 102 cm for men and ≥ 88 cm for women. The relationship between CDAI and obesity, including abdominal obesity, was analyzed using logistic regression and subgroup analyses. A total of 25,553 participants were analyzed. With higher tertiles of the CDAI, both obesity (41.28% vs. 38.62 vs. 35.09%, P < 0.001) and abdominal obesity (63.75% vs. 59.54 vs. 52.09%, P < 0.001) prevalence notably declined. Adjusting for multiple confounders, the CDAI was found to be independently linked to obesity (OR = 0.980, 95%CI = 0.971-0.989, P < 0.001) and abdominal obesity (OR = 0.972, 95%CI = 0.963-0.982, P < 0.001) risks. Subgroup analyses revealed a stronger relationship between CDAI and obesity in non-hypertensive individuals and a more significant association with abdominal obesity in women and those without hypertension. Our findings reveal a negative relationship between CDAI levels and both general and abdominal obesity. Additional extensive research is necessary to investigate CDAI's contribution to obesity.