VITAL-DEP: Depression Endpoint Prevention in the VITamin D and OmegA-3 TriaL

The VITamin D and OmegA-3 TriaL (VITAL; NCT 01169259) is an ongoing randomized clinical trial in 25,871 U.S. men and women investigating whether taking daily dietary supplements of vitamin D3 (2000 IU) or omega-3 fatty acids (Omacor® fish oil, 1 gram) reduces the risk of developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses. This ancillary study is being conducted among participants in VITAL and will examine whether vitamin D or fish oil: 1) reduces risk of clinical depressive syndrome, 2) yields better mood scores over time, compared to placebo.