The sex-specific role of plasma folate in mediating the association of dietary quality with depressive symptoms

Abstract

Folate deficiency has been implicated in the etiology of unipolar depression. In this study, we attempted to cross-link plasma folate, depressive symptoms, and dietary quality (or dietary intake of folate) together in a comprehensive framework, while examining effect modification of those associations by sex. This was a cross-sectional, population-based study of 1681 participants aged 30-64 γ (Healthy Aging in Neighborhoods of Diversity across the Lifespan Study). Participants were administered the Center for Epidemiologic Studies Depression scale (CES-D). Measures of plasma folate and dietary intakes (2 24-h recalls) fromwhich the 2005-Healthy Eating Index (HEI) was computedwere available.Multivariate logistic regression and structural equationmodeling (SM) were conducted. Compared with the lowest tertile, themiddle and uppermost tertiles of plasma folate were associated with a 39-40%reduced odds of elevated CES-D (≥16) among women [adjusted odds ratio (T3 vs. T1) = 0.60 (95% CI = 0.42-0.86); P = 0.006]. Confounding of this association by HEItotal was noted among both men and women, although dietary folate did not confound this association appreciably. In SM, plasma folate completely mediated the inverse HEI total-CES-D association among men only, specifically for HEI 2 (higher intakes of whole fruits), HEI3 (total vegetables), HEI5 (total grains), HEI6 (whole grains), HEI7 (milk), and HEI12 (lower discretionary energy). Among women, HEItotal and 4 components had an inverse direct effect on CES-D score, suggesting a mechanism that is independent of plasma folate. Depressive symptoms in our study may be alleviated by improving overall dietary quality, with plasma folate playing a potential mediating role only among men. © 2010 American Society for Nutrition.