Can a fish oil supplement help improve your depression symptoms?

potential to protect the heart, but they're also garnering interest for their effects on the brain. Plus, they are available without a prescription and are much less expensive than antidepressants.

But does research show that fish oil can truly help relieve depression? Is it better used as an adjunct to antidepressant therapy? And is it safe to try it?

The value of omega-3s

Also known as essential fatty acids, omega-3s are a type of polyunsaturated fatty acid and are one of three kinds of naturally occurring fats in the human diet. (The others are saturated and monounsaturated fats.) Your body cannot manufacture omega-3s; they are found mainly in seafood but also in nuts, some oils and eggs, and to a small extent, red meat. Omega-3s contain large amounts of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are believed to have numerous health benefits, such as maintaining proper functioning of the nervous system.

Omega-3s are a building block of cell membranes, and it's thought that increasing omega-3 levels makes it easier for serotonin (a chemical that relays impulses between nerve cells) to pass through cell walls. Consuming more omega-3s can also increase serotonin in the body; low levels of serotonin are linked with depression. In countries with high consumption of fish and omega-3s, there tend to be low depression rates. The opposite is true, as well, as is the case in the United States.

Some experts have blamed American eating patterns for the rise in depression. As we have tried to adopt a heart-healthy diet, we have cut back on red meat and eggs—two good non-seafood sources of omega-3s. We use a lot of oils like corn, soybean and sunflower, which are low in omega-3s. And we're now eating more omega-6 fatty acids than ever before in fast food and processed foods. Historically, humans have eaten omega-3s and omega-6s in equal proportions. Now, most of us eat far more omega-6s, and the resultant rise in this type of fatty acid has paralleled the rise in depression rates. However, the increase in the depression rate is almost certainly the result of many factors, with these dietary issues as one possible contributor.

The research

Study findings on omega-3s and depression have shown inconsistent results. As with any alternative or complementary therapy, there's no standardized preparation or formula, and the Food and Drug Administration (FDA) doesn't regulate supplements the way it does prescription drugs. However, several clinical trials have shown promise.

A 2009 Canadian study examined for the first time the effectiveness of omega-3s in menopausal women with major depression as well as less severe depression. Participants who were randomized to take 1 g of omega-3 capsules a day for eight weeks reported a lessening of depression compared with a group who took a placebo, especially among those whose symptoms were less severe.

A 2010 review article of complementary therapies for depression in the Journal of Clinical Psychiatry found that several clinical trials have shown promising results when omega-3s are used as an adjunct to antidepressant therapy. However, the study of omega-3s' effectiveness as a stand-alone treatment for major depression has yielded limited and conflicting results. For example, a small study of 36 adults with major depression found that 2 g of DHA per day was not more effective than a placebo at relieving symptoms.

The type of fish oil supplement used may be a determining factor, as a study presented at the 2010 American College of Neuropsychopharmacology Conference showed. Researchers conducted a meta-analysis of 15 randomized, placebo-controlled studies on the use of omega-3s to treat depression. They found that DHA, when used alone, did not significantly improve depressive symptoms compared with a placebo. But supplements composed of EPA or a combination of DHA and EPA (with EPA predominant) were consistently effective.

Publication Review By: Karen L. Swartz, M.D.

Published: 21 Aug 2013

Last Modified: 21 Aug 2013