The role of vitamin D in the prevention of late-life depression

Background: In this article, we review current evidence regarding potential benefits of vitamin D for improving mood and reducing depression risk in older adults. We summarize gaps in knowledge and describe future efforts that may clarify the role of vitamin D in late-life depression prevention. Methods: MEDLINE and PsychINFO databases were searched for all articles on vitamin D and mood that had been published up to and including May 2015. Observational studies and randomized trials with 50 or more participants were included. We excluded studies that involved only younger adults and/or exclusively involved persons with current depression. Results: Twenty observational (cross-sectional and prospective) studies and 10 randomized trials (nine were randomized placebo-controlled trials [RCTs]; one was a randomized blinded comparison trial) were reviewed. Inverse associations of vitamin D blood level or vitamin D intake with depression were found in 13 observational studies; three identified prospective relations. Results from all but one of the RCTs showed no statistically significant differences in depression outcomes between vitamin D and placebo groups. Limitations: Observational studies were mostly cross-sectional and frequently lacked adequate control of confounding. RCTs often featured low treatment doses, suboptimal post-intervention changes in biochemical levels of vitamin D, and/or short trial durations. Conclusion: Vitamin D level-mood associations were observed in most, but not all, observational studies; results indicated that vitamin D deficiency may be a risk factor for late-life depression. However, additional data from well-designed RCTs are required to determine the impact of vitamin D in late-life depression prevention. (C) 2016 Elsevier B.V. All rights reserved.