Inverse association between dietary antioxidant intake and endometriosis among US women: A cross-sectional NHANES study.

Abstract

BACKGROUND: Endometriosis affects approximately 10% of women of reproductive age worldwide. Emerging evidence suggests a link between dietary antioxidants and endometriosis risk, prompting interest in measures like the Composite Dietary Antioxidant Index (CDAI). METHODS: Data from the 2001-2006 U.S. National Health and Nutrition Examination Survey (NHANES) were analyzed. CDAI was calculated based on dietary intake of vitamins A, C, E, zinc, selenium, and carotenoids. Weighted multiple logistic regression assessed association between CDAI, its components, and endometriosis, while restricted cubic spline (RCS) analysis explored potential non-linear relationships. Subgroup and sensitivity analyses tested the robustness of the findings. RESULTS: Among 3,069 women, 214 reported endometriosis. After full adjustment, higher CDAI scores were significantly associated with lower endometriosis risk (OR = 0.907; 95 % CI [0.840-0.979], P = 0.016), with a decreasing trend across quartiles (Q4 vs. Q1: OR = 0.352; 95 % CI [0.184-0.673], P for trend = 0.004). Intakes of vitamin A and C showed consistent inverse associations as continuous variables. For vitamin E, no significant association was found when analyzed continuously, but participants in the highest quartile had significantly lower endometriosis risk compared to the lowest quartile (OR = 0.477; 95 % CI[0.247-0.919], P for trend = 0.022). RCS analysis indicated a linear negative relationship between CDAI, vitamin A intake, and endometriosis (P for non-linear = 0.383 and 0.180, respectively). Findings remained robust across subgroup and sensitivity analyses. CONCLUSIONS: An inverse association was observed between higher CDAI scores and the prevalence of endometriosis. However, further prospective studies are needed to better understand this association.