Figure 1.

Forest plots of randomized controlled trials investigating the effect of vitamin D supplementation on depressive symptoms, overall and by depression and vitamin D status. Five weighted pooled intervention effect estimates (diamonds) are shown: one for the full set of 7 trials (overall) and one each for nondepressed participants, depressed participants, participants with sufficient vitamin D, and participants with insufficient vitamin D. Data are expressed as standardized mean differences with 95% CI, using the inverse-variance method and random-effects models. Trials categorized as “nondepressed” did not specifically recruit participants with depression or included participants whose baseline depressive symptom scores were indicative of no or mild depression; trials categorized as “depressed” included participants with clinically significant depressive symptoms and/or major depressive disorder. Categorization of trials as “sufficient vitamin D” or “insufficient vitamin D” was based on participants’ baseline concentrations of 25-hydroxyvitamin D and established cutpoints for interpreting these concentrations (7).