Perinatal depression is a prevalent mood disorder associated with nutritional factors, yet the relationship between comprehensive dietary antioxidant capacity and perinatal depression remains unclear. This study aimed to investigate the association between the Composite Dietary Antioxidant Index (CDAI) and depressive symptoms in a sample of U.S. perinatal women. We analyzed a nationally representative sample of 1,093 pregnant and postpartum (within 18 months) women from NHANES 2005–2018. The CDAI, a composite metric integrating six key antioxidant nutrients (vitamins A, C, E, zinc, selenium, carotenoids), was derived from 24-hour dietary recalls. Depressive symptoms were quantified using the PHQ-9, with a score ≥ 10 defining clinically significant depression. We employed segmented regression modeling to identify a potential inflection point in the CDAI-depression relationship, moving beyond the constraints of linear assumptions. The association was evaluated comprehensively using both linear (for symptom severity) and logistic (for clinical caseness) models. Robustness was assessed through extensive sensitivity analyses, and we further explored effect modification by key lifestyle factors. We observed a significant nonlinear association between the CDAI and depressive symptoms. Below the identified inflection point (CDAI ≤ − 2.75), indicative of suboptimal antioxidant status, each unit increase in CDAI was significantly associated with both a 0.80-point reduction in PHQ-9 score (β = −0.80, 95% CI: −1.22, − 0.38; P = 0.0002) and a 39% lower odds of clinical depression (OR = 0.61, 95% CI: 0.45, 0.83; P = 0.0019). This protective association was most potent in vulnerable subgroups, including never-smokers (P-interaction = 0.0007) and Non-Hispanic Black women (P-interaction = 0.014). In this cross-sectional study, we observed a significant nonlinear association between the CDAI and depressive symptoms among U.S. perinatal women. Lower dietary antioxidant capacity was linked to a significantly increased severity of depressive symptoms and higher odds of clinical depression, whereas higher antioxidant intake beyond the threshold did not yield further incremental benefits.
Zhang et al. (Fri,) studied this question.