Vitamin D Supplementation Does Not Reduce Depression Risk in Older Women
Results from a very large, population-based, randomized study
Although observational studies have linked symptoms of depression to low vitamin D levels, few randomized, controlled trials have tested whether vitamin D supplementation can treat or prevent depression. These studies had modest and, often, selective samples and yielded conflicting results. Researchers have now analyzed data from the Women’s Health Initiative Calcium and Vitamin D Trial in 36,282 women aged 50 to 80 who were randomized to 400 IU vitamin D (with 1000 mg calcium) or to placebo. Depression symptoms and antidepressant use (as proxy for depression) were measured at randomization and 2 years later (symptoms measured at follow-up in only 2263 women).
The two groups had low baseline levels of antidepressant use (7%), threshold depression (10%), and total vitamin D intake (mean, 366 IU). Supplementation for 2 years had absolutely no effect on risk for depressive symptoms above threshold or on antidepressant use either in the entire group or in the subgroup without threshold depression at baseline.
Comment: This extremely large and meticulously done study found no benefit from vitamin D for depression. The results suggest that observed links between low vitamin D and depression may be due to confounding effects of lifestyle and diet. Although the vitamin D dose might have been too small, the authors note that when added to intake from food, it achieved the daily dose recommended by the Institute of Medicine. This study does not address the question of whether depressed patients with low vitamin D levels would improve with vitamin D supplements. Adequate vitamin D is still important for optimal health in multiple ways, but patients with depression will have to do more than raise their vitamin D levels to feel better.
Peter Roy-Byrne, MD
Published in Journal Watch Psychiatry August 30, 2012
Bertone-Johnson ER et al. Vitamin D supplementation and depression in the Women’s Health Initiative Calcium and Vitamin D Trial. Am J Epidemiol 2012 Jul 1; 176:1.
[Link to free full-text Am J Epidemiol article PDF | PubMed ® abstract]