Omega-3 may benefit depression symptoms, but only for depressive people

“Why would you expect a low dose (<400mg) of EPA+DHA to have an effect on depression in non-depressed subjects?” asks GOED's Dr Harry Rice.

Daily supplements of omega-3 fatty acids may improve symptoms of depression, but only in people taking antidepressant medications, according to a new study.

Despite a general finding that omega-3s do not impact depressive symptoms and optimism levels in heart attack patients, results published in the American Journal of Clinical Nutrition indicate that people taking antidepressant medications – in other word, people who are actually suffer from depression – did benefit from the omega-3 supplements.

“[Low-doses of supplementation with either EPA-DHA or ALA] did not affect depressive symptoms and dispositional optimism in post- [myocardial infarction] patients, most of whom had no psychiatric diagnosis and no depressed mood,” reported researchers from Wageningen University in the Netherlands.

“However, we found that the small group of patients who were prescribed antidepressant medications at baseline showed a somewhat greater improvement in depressive symptoms when taking EPA-DHA compared with placebo,” they added.

Reaction

The study’s findings were described by Harry Rice, PhD, VP of regulatory and scientific affairs for the Global Organization for EPA and DHA Omega-3s (GOED) as “a classic floor effect.

“Why would you expect a low dose (<400mg) of EPA+DHA to have an effect on depression in non-depressed subjects?” asked Dr Rice.

“This secondary analysis was set-up for failure. In many studies, higher doses of long-chain omega-3s have been shown to ameliorate depressive symptoms in depressed individuals.”

Omega-3 and depression

The link between omega-3 and mood is complex and data to date is contradictory. The largest clinical trial to date in people with major depressive episodes reported a “trend toward superiority of omega-3 supplementation over placebo in reducing depressive symptoms” with omega-3 doses of 1.2 grams per day (Journal of Clinical Psychiatry, 2011, Vo. 72, pp. 1054-1062).

The new study adds to this growing body of science, and indicates that a relatively low dose provides no general benefits. The Netherlands-based researchers recruited over 4,000 heart attack patients and assigned them to consume margarine spreads providing a daily dose of 2 grams of plant-derived alpha-linolenic acid (ALA) , or 400 milligrams fish-derived EPA and DHA, or ALA plus EPA/DHA, or placebo for 40 months.

Symptoms of depression were assessed using the 15-item Geriatric Depression Scale, with results showing no differences between the groups for depressive symptoms and dispositional optimism.

“However, we found that the small group of patients (36 people) who were prescribed antidepressant medications at baseline showed a somewhat greater improvement in depressive symptoms when taking EPA-DHA compared with placebo (40 people),” report the researchers.

“Further well-designed randomized controlled trials are required in patients with a major depressive disorder with the use of high doses of EPA-DHA and further studies with the use of ALA supplementation,” they concluded.

Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.111.018259
"Effects of n23 fatty acids on depressive symptoms and dispositional optimism after myocardial infarction"
Authors: E.J. Giltay, J.M. Geleijnse, D. Kromhout