Marine omega-3 supplementation fails to prevent depression

The use of marine omega-3 supplements by adults does not appear to prevent the onset of depression, researchers reported on Dec. 21, 2021 in JAMA/Journal of the American Medical Association.

“Among adults aged 50 years or older without clinically relevant depressive symptoms at baseline, treatment with omega-3 supplements compared with placebo yielded mixed results, with a small but statistically significant increase in risk of depression or clinically relevant depressive symptoms but no difference in mood scores, over a median follow-up of 5.3 years,” the authors said

As background the authors noted that marine omega-3 fatty acid supplements are widely used to treat depression but their efficacy in preventing depression in the general adult population is unknown. The objective of this study was to test effects of marine omega-3 supplementation on late-life risk of depression.

A total of 18,353 adults were enrolled in the study. Of these subjects, 16, 657 were at risk of incident depression (no prior depression) and 1,696 were at risk of recurrent depression (previous depression, but not for at least 2 years before enrollment).

Of the total study population, 9,171 were randomized to marine omega-3 treatment and 9,182 were randomized to placebo.

The co-primary endpoints were risk of depression or clinically relevant depressive symptoms and mean difference in mood score (8-item Patient Health Questionnaire [PHQ-8] depression scale).

Of the 18, 353 randomized subjects (mean age, 67.5 and years; 49.2% women), 90.3% completed the trial (93.5% among those alive at the end of the trial). Median treatment duration was 5.3 years.

Depression risk was higher for marine omega-3 subjects (651 events, 13.9 per 1000 person-years) than placebo subjects (583 events, 12.3 per 1000 person-years. (P = .03).

The investigators reported no significant differences between marine omega-3 and placebo groups for longitudinal mood scores. 

“These findings do not support the use of omega-3 fatty acid supplements in adults to prevent depression,” the authors concluded.