While some research is encouraging, larger studies need to be done to determine the effectiveness of omega-3s for different types of depression and proper dosages. While a study on fish oil and depression in menopausal women found that it was more helpful for people with milder rather than severe depression, some experts have asserted that fish oil supplements—like antidepressants—are most helpful for severe symptoms.

Fish oil supplements do not elevate mood in people who are not depressed. Fish oil also does not appear to be helpful for people with depression accompanied by an anxiety disorder. For now, it may be potentially helpful for people with depression to take fish oil in addition to an antidepressant, but there is no evidence for using it alone or instead of traditional medications.

If you are considering adding a fish oil supplement to your treatment regimen, talk to your doctor first—and never stop taking any prescribed medication without your doctor's recommendation.

When buying a fish oil supplement, look for the United States Pharmacopeia (USP) seal on the packaging. Although it doesn't make any claims about the effectiveness of a product, this labeling ensures that the product meets safety, purity and consistency standards. Based on research, you may also want to look for formulations that contain more EPA than DHA.

The optimum dose of omega-3s for depression is not known, but the studies discussed here found improvement with dosages between 1 g and 2 g per day. As far as supplements are concerned, omega-3s are generally considered safe, and the FDA advises a dosage up to 3 g a day. Although they offer many heart-health benefits, fish oil supplements theoretically could increase the risk of bleeding if taken in high doses.

Food vs. supplements

The benefits of fish oil supplements are also present in the fish themselves. Look for oily fish such as sardines, mackerel, salmon, snapper, trout and canned white tuna, and shellfish such as mussels and oysters. Flaxseed, canola and soybean oils are also good sources of omega-3s, but only if they’re unheated, as in salad dressing.

Eating these foods several times a week could provide enough omega-3 fatty acids to ease depression—provided you like fish or aren't a strict vegetarian. Many people are concerned about mercury consumption from eating fish. Farm-raised salmon, for example, can be an alternative because it doesn't contain mercury, but depending on what these fish are fed, they may not contain enough omega-3s.

Although there are certainly dietary sources of omega-3s, supplements may be the easiest, safest and most convenient way for many people to get an adequate amount of omega-3 fatty acids. Side effects are minor and include burping or an unpleasant taste. Just be wary of cod liver oil. While it is a good source of omega-3s, it contains too much vitamin A to be safe in large doses.

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

Published: 21 Aug 2013

Last Modified: 21 Aug 2013