Dec. 22, 2021 -- Fish oil supplements do not help prevent depression or boost mood, new research suggests.

The VITAL-DEP study included more than 18,000 participants. Among adults 50 or older, none of whom were clinically depressed, long-term use of marine omega-3 fatty acid (omega-3) supplements did not reduce risk for depression or symptoms of depression — or make a difference in the quality of mood.

In fact, there was a small increase found in risk for depression or depressive symptoms with omega-3 supplements.

"While a small increase in risk of depression was inside the statistical margin of significance, there was no harmful or beneficial effect of omega-3 on the overall course of mood during the roughly 5 to 7 years of follow-up," lead author Olivia I. Okereke, MD, of Massachusetts General Hospital and Harvard Medical School, says.

The findings were published online this week in the Journal of the American Medical Association.

Assessing General Population Risk

For many years, experts have recommended omega-3 supplements for depression in some high-risk patients, Okereke says, but there are no established guidelines for its use.

The study enrolled 18,353 older adults (average age, 67.5 years; 49% women). Of these, 16,657 were at risk for incident depression, defined as having no previous history of depression; and 1,696 were at risk for recurrent depression, defined as having a history of depression but not having undergone treatment for depression within the past 2 years.

Roughly half the participants were randomly assigned to receive omega-3 fatty acids and the other half to a placebo for an average of 5.3 years.