Relationship of comprehensive dietary antioxidant index and hypothyroidism risk: evidence from the National Health and Nutrition Examination Surveys 2007–2012

Hypothyroidism is a common thyroid disease affecting the health of the global population and oxidative stress and inflammation are involved in the pathophysiological process of hypothyroidism. Comprehensive dietary antioxidant index (CDAI), representing the overall dietary antioxidant capacity, has been proved to be associated with a variety of diseases. However, association between CDAI and hypothyroidism risk remains unclear. This study aims to evaluate the association of CDAI and hypothyroidism risk.

Data of this study were extracted from the National Health and Nutrition Examination Surveys (NHANES) database 2007–2012. CDAI, represents the overall dietary nutrients capacity, was calculated by selenium, zinc, magnesium, vitamin A, C and E. Thyroid stimulating hormone (TSH) > 5.6 mIU/L was defined as hypothyroidism. The weighted multivariate logistic regression models and propensity score matching (PSM) analysis were utilized to evaluate the relationship between CDAI and hypothyroidism, with odds ratio (ORs) and 95% confidence intervals (CIs). Subgroup and sensitivity analysis were further evaluated the relationship between CDAI and hypothyroidism. Moreover, the association between the components of CDAI and hypothyroidism was also explored.

Totally, 7,959 subjects with information of complete dietary intake and thyroid function measurement were included. Of whom, 213 (2.68%) subjects had hypothyroidism. After adjusted all covariates, we observed high CDAI was related to low hypothyroidism risk (OR = 0.44, 95%CI: 0.27–0.71). This relationship was prominent in subjects with aged < 65 years old (OR = 0.32, 95%CI: 0.16–0.62), male (OR = 0.39, 95%CI: 0.15–0.99) and BMI ≥ 25 kg/m² (OR = 0.38, 95%CI: 0.19–0.76). The association between high CDAI and low hypothyroidism risk remained significant when subjects using thyroid hormones were excluded (OR = 0.47, 95%CI: 0.27–0.81).

High CDAI was related to low hypothyroidism risk among U.S. adults. Our finding showed that the intake of an antioxidant-rich dietary is a potential method to reduce the risk of hypothyroidism.