Background: Vitamin D may plausibly reduce the occurrence of depression in postmenopausal women; however, epidemiologic evidence is limited, and few prospective studies have been conducted.
Objective: We conducted a cross-sectional and prospective analysis of vitamin D intake from foods and supplements and risk of depressive symptoms.
Design: Study participants were 81,189 members of the Women's Health Initiative (WHI) Observational Study who were aged 50-79 y at baseline. Vitamin D intake at baseline was measured by food-frequency and supplement-use questionnaires. Depressive symptoms at baseline and after 3 y were assessed by using the Burnam scale and current antidepressant medication use.
Results: After age, physical activity, and other factors were controlled for, women who reported a total intake of ≥800 IU vitamin D/d had a prevalence OR for depressive symptoms of 0.79 (95% CI: 0.71, 0.89; P-trend < 0.001) compared with women who reported a total intake of <100 IU vitamin D/d. In analyses limited to women without evidence of depression at baseline, an intake of ≥400 compared with <100 IU vitamin D/d from food sources was associated with 20% lower risk of depressive symptoms at year 3 (OR: 0.80; 95% CI: 0.67, 0.95; P-trend = 0.001). The results for supplemental vitamin D were less consistent, as were the results from secondary analyses that included as cases women who were currently using antidepressant medications.
Conclusions: Overall, our findings support a potential inverse association of vitamin D, primarily from food sources, and depressive symptoms in postmenopausal women. Additional prospective studies and randomized trials are essential in establishing whether the improvement of vitamin D status holds promise for the prevention of depression, the treatment of depression, or both.