Omega-3 Fatty Acids for Depression? The Jury Is Still Out

Health

A meta-analysis says success depends on a high percentage of EPA, but a large study using this dose finds only small effects in less severely ill patients.
Associations between depression and low fish consumption or low blood levels of omega-3 polyunsaturated fatty acids (PUFAs) have prompted numerous small studies of PUFAs for treating depression. Two recent reports provide new insights.
In a meta-analysis of 15 mostly small, placebo-controlled trials in depressed patients (2 studies with >100 patients; total N, 916), Sublette and colleagues dichotomized the studies by the percentage of eicosapentaenoic acid (EPA) content used in the PUFA preparation. The eight studies using at least 60% EPA showed a moderate antidepressant effect; no effect was seen in studies using lower levels of EPA. Age and treatment duration were unrelated to results. Seven studies used EPA as monotherapy, but whether effects varied by approach (monotherapy vs. augmentation) was not reported.
Lespérance and colleagues conducted a randomized, placebo-controlled trial of PUFAs in 432 depressed patients, the largest trial reported so far. The preparation contained over 80% EPA (1050 mg); the study included patients with comorbid anxiety disorders and was stratified by whether patients were using antidepressants (40% of patients). PUFAs showed no antidepressant effect in the entire group, but in preplanned analyses they had a small effect in a subgroup without comorbid anxiety (47% of patients) and showed a trend toward positive effects when used as monotherapy (60% of patients) compared with augmentation.
Comment: These two reports suggest some modest antidepressant effects for PUFAs in depressed patients who are less likely to be treatment-resistant (i.e., lacking anxiety and not already taking antidepressants). Both studies support using an EPA dose (1–2 g) constituting at least 60% of the entire preparation. Because almost two thirds of the U.S. population are already taking supplements or alternative treatments, this option may be appealing to many, although it is likely to be effective only as an initial treatment option for less difficult-to-treat depression.
— Peter Roy-Byrne, MD