An L-shaped association between composite dietary antioxidant index and stroke: Evidence from NHANES 2011-2020

Objectives Antioxidant diets are considered to be protective factors against stroke. However, comprehensive measurement and evaluation of antioxidant diets are lacking. This study aimed to investigate the correlation between the Composite Dietary Antioxidant Index (CDAI) and stroke in adults. Materials and methods In this study, based on the National Health and Nutrition Examination Survey (NHANES) 2011-2020 data, multivariate logistic regression, smoothing curve fitting, and threshold effect analysis were used to explore the relationship between CDAI and stroke. Subgroup analyses and interaction tests were conducted to assess the stability of this association within the population. Results Among 12,922 U.S. adults, there was a significant negative correlation between CDAI and the prevalence of stroke. In the fully adjusted model, the risk of stroke was reduced by 4 % for each 1-unit increase in CDAI (OR [95% CI] = 0.96 [0.93, 0.99]). Participants in the highest quartile of the CDAI had a 37 % lower risk of stroke than those in the lowest quartile (OR [95% CI] = 0.63 [0.47, 0.84]). This negative correlation remained stable across subgroups. Furthermore, the study revealed an L-shaped association between CDAI and stroke through smoothing curve fitting. The threshold effect analysis further identified the inflection point as -1.55. Conclusions This study revealed an L-shaped relationship between CDAI and stroke. Keeping CDAI in the proper range may help prevent stroke in the general population.