The associations between different sources of dietary omega-3 and omega-6 fatty acids and the risk of depression have not been prospectively studied.

So, researchers at the Harvard School of Public Health, in Boston, examined these associations.

First, the details.

  • 54,632 US older women from the Nurses’ Health Study who were free from depressive symptoms were followed for 10 years.
  • Information on diet was obtained from validated food-frequency questionnaires.
  • Clinical depression was defined as reporting both physician-diagnosed depression and regular antidepressant medication use.

And, the results.

  • There were 2823 cases of depression during the study.
  • Intake of long-chain omega-3 fatty acids from fish was not associated with a risk for depression.
  • However, higher alpha-linolenic acid (ALA) intake was significantly associated with lower depression risk.
    • ALA is the only omega-3 fatty acid found in vegetable products, and it is most abundant in canola oil.
  • This association between ALA and depression was significantly stronger in women with low linoleic acid (LA) intake.
    • LA is an unsaturated omega-6 fatty acid.

The bottom line?

The authors concluded that their findings “do not support a protective effect of long-chain omega-3 from fish on depression risk. Although these data support the hypothesis that higher ALA and lower LA intakes reduce depression risk.

These association warrant further investigation, say the authors.

4/16/11 18:38 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.