Can Fish Oil Prevent Depression in the General Population?

Omega-3 (ω-3) fatty acids occasionally are used as an adjunct to depression treatment, based on results of some clinical trials. A related question is whether taking ω-3 supplements can prevent depression in the general population. To address this question, researchers used data from the previously published VITAL study to assess 18,000 participants (mean age, 68) who were randomized to a 1-g capsule of fish oil (465 mg eicosapentaenoic acid [EPA] and 375 mg docosahexaenoic acid) or placebo daily (NEJM JW Gen Med Dec 15 2018 and N Engl J Med 2019; 380:23). Most participants had no history of depression, and the remainder had no depression for at least 2 years.

During median follow-up of longer than 5 years, the incidence of clinically diagno…