Some studies, and many ads, suggest that omega-3 supplements are helpful for improving mental health. But a systematic review of research has found the supplements are probably ineffective in treating or preventing depression and anxiety.
The analysis, in the British Journal of Psychiatry, included a broad range of long-term trials of omega-3 fatty acid supplementation. Omega-3s are found in fatty fish like salmon and other foods. Neither length of treatment nor size of dosage demonstrated effectiveness.
The review included 32 randomized trials testing supplements of omega-3, linoleic acid and polyunsaturated fatty acids with 41,467 participants. There were 13 trials of at least six months’ duration testing higher and lower doses of omega-3s in more than 26,000 subjects. None showed benefits.
Two small studies, one in 61 older men with mild or moderate depression, and one in 24 people with depression and Parkinson’s disease, did report minimal depression remission with higher doses of omega-3s. There were six studies of omega-3s and anxiety, all suggesting that the substances have little or no effect on symptoms.
The lead author, Lee Hooper of the University of East Anglia, said that while the supplements do no good, they probably do no harm. “I wouldn’t tell people to stop taking them on the basis that they’re harmful,” she said, “except to your bank balance.”