Even briefly boosting your intake of omega-3 fatty acids might provide months of protection from certain forms of depression, according to a study conducted by a team of international researchers and published in the journal Biological Psychiatry.

"The study shows that even a short course (two weeks) of a nutritional supplement containing one such omega-3 polyunsaturated fatty acid (EPA) reduced the rates of new-onset depression to 10%," said senior author Carmine Pariante of King's College London.

Omega-3 fatty acids, found in high quantities in fish oil, have been shown to reduce the risk of heart disease and to act as anti-inflammatories in the body. Research has also suggested that they may have cognitive and even psychiatric benefits. In a prior study, also in Biological Psychiatry, the same researchers found that people with lower levels of the omega-3 eicosapentaenoic acid (EPA) in their blood were significantly more likely to develop depression.

Reduces inflammation, depression

In the new study, the researchers sought to see whether omega-3 supplementation could decrease depression risk in a population more prone to the condition. Studies have shown that inflammation increases the risk of depression, and that inflammation-promoting drugs can produce depression as a common side effect. For example, six months of treatment with interferon-alpha therapy (used for chronic hepatitis C infection) leads to depression in about 30 percent of patients.

In a double-blind study, the researchers randomly assigned 153 hepatitis C patients to take a daily supplement for two weeks, consisting of either a placebo, EPA or the omega-3 docosahexaenoic acid (DHA). After the intervention, all the patients were given a 24-week (six-month) course of interferon-alpha treatment. All participants were regularly screened for depression.

The researchers found that EPA (but not DHA or placebo) treatment reduced the subsequent rate of depression. In addition, those who did become depressed experienced a later onset of the condition if they had previously had the EPA or DHA treatment. Neither EPA nor DHA treatment led to any adverse effects.

The researchers speculated that omega-3s may help protect people from depression by replenishing the body's store of anti-inflammatories, thus making inflammation-induced depression less likely.

"These new data provide promising support for omega-3 fatty acids to prevent depression, complementing other studies where omega-3's were found to enhance antidepressant treatment," said Dr. John Krystal, editor of Biological Psychiatry.

Omega-3s improve mental health