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