Depression is a mood disorder characterized by profound sadness, fatigue, altered sleep and appetite, as well as feelings of guilt or low self-worth. It is the most common mental health disorder worldwide, affecting as many as 322 million people. Many people with depression do not respond to antidepressant therapies. A new study suggests that omega-3 fatty acids are beneficial in treating symptoms of depression.

Omega-3 fatty acids are polyunsaturated fats that are essential for human health. They play critical roles in the development and function of the nervous system. Evidence suggests that low intake of omega-3 fatty acids contributes to depression.

The double-blind, randomized, controlled trial involved more than 430 outpatients enrolled in treatment programs at eight academic and psychiatric clinics in Canada. The authors of the study randomized the patients to take either a supplement containing omega-3 fatty acids (1,050 milligrams of eicosapentaenoic acid and 150 mg/d of docosahexaenoic acid) or a placebo daily for eight weeks. The patients provided self-reports about their depressive symptoms and underwent clinical psychiatric assessment.

At the end of the study, the patients who took the omega-3 supplement showed improvements in both self-reported and clinical assessments of their symptoms, particularly among those who had no accompanying anxiety disorders. These improvements were comparable to those observed with common antidepressant drugs. Future studies directly comparing the efficacy of omega-3 fatty acid supplementation to drug therapies are needed.

• Link to study abstract.

• Learn more about depression in our overview article.