Do Happy Fish Make Happy Women?
Author: Dr. Stephen Chaney
The days are getting shorter, and those shorter days can lead to depression. You may have seen the recent headlines saying “Omega-3 fatty acids may decrease the risk of depression in women”. If you suffer from seasonal depression, should you be stocking up on fish oil capsules? Let’s look at the study behind the headlines.
The Theory Behind The Study
Depression appears to be increasing in modern society. For example, between 1991 and 2002, the prevalence of major depression has more than doubled in the United States from 3.3% to 7.1%.
There are many causes of depression, but some experts blame the dramatic increase in omega-6 fatty acids in the diet. For example, per capita consumption of soybean oil, much of it in processed foods, has increased 1000-fold during the past century. That’s a concern because omega-6 fatty acids interfere with the body’s ability to convert vegetable sources of omega-3 fatty acids into the longer chain omega-3 fatty acids thought to be effective in reducing depression.
This has lead to the hypothesis that omega-3 fatty acids in the diet may help prevent depression, and a number of clinical studies have supported that hypothesis.
How Was The Study Designed?
The study (M. A. Beydoun et al, J. Nutr., doi: 10.3945/jn.113.179119, 2013) looked at 1,746 adults age 30-64 living in Baltimore Maryland. The participants were a representative sample of African Americans and whites, men and women. Omega-3 fatty acid intake was based on two 24-hour dietary recalls. Depressive symptoms were based on something called CES-D, which is a 20 item, self-reporting symptom rating scale.
What Did The Study Actually Show?
The results were pretty dramatic for women:
- Women with the highest intake of omega-3 fatty acids/day were 49% less likely to suffer from depression than women with the lowest intake.
- No significant effect of omega-3 fatty acid intake on the prevalence of depression was seen for the men in this study. This was the first study to look at men and women separately, so it’s not yet clear whether this is a true sex-specific difference or simply due to the relatively small sample size and reduced incidence of depression in men.
Limitations Of The Study:
There were numerous limitations to this study, but the most important were:
- It did not ask whether the participants were taking fish oil supplements, and it did not substantiate the dietary recalls by measuring actual levels of omega-3 fatty acids in the blood.
- It just measured associations, not cause and effect.
The Bottom Line:
This is not a particularly strong study, but it is consistent with a least half a dozen other studies that have obtained similar results. So, based on the total body of published studies my recommendations are:
1) If you are a woman and you’re suffering from mild depression you might want to talk with your doctor about increasing your omega-3 fatty acid intake before you start taking an anti-depressive medication. Omega-3 fatty acids may reduce heart disease risk, lower inflammation and provide other benefits. The drugs generally have side effects rather than side benefits.
2) We don’t have any good data yet on what dose of omega-3 fatty acids are needed, but the 500-1,000 mg/day that the NIH recommends for heart health might be a good starting place.
3) If you’re a guy, this paper suggests that the jury is out about whether omega-3s can help you with depression. More studies will be required. In the meantime, just remember that omega-3s have lots of other health benefits.
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.