Other Omega3 Benefits

Omega-3 fatty acids from fish oil have become a nutrition sensation over the past 15 or 20 years.

If you believe what you see in the media, diets rich in omega-3 fatty acids reduce your risk of heart disease, diabetes, many types of cancer, anxiety and depression - just to name a few. But how much of this is true, and how much is just hype? The beneficial effects of omega-3 fatty acids on reducing the risk of heart attack and stroke have been established by multiple randomized clinical trials, but many of the other supposed benefits are based primarily on associations rather than on hard clinical data.

That is why three recent randomized, double blind, placebo controlled clinical studies caught my eye.

#1) In the first study (Kiecolt-Glaser et al, Brain, Behavior and Immunity, 25: 1725-1734, 2011) 68 healthy medical students at Ohio State were given either placebo capsules or capsules containing 2.5 gm of omega-3 fatty acids (primarily EPA or DHA) for 12 weeks. The placebo contained the fatty acid composition of the standard American diet (SAD) and was given a fishy taste to make it indistinguishable from the omega-3 capsules. None of the medical students had been diagnosed with an anxiety disorder, but all of them reported the normal anxiety associated with medical school. (As an anxiety- inducer (ie, Professor) for the past 39 years I am well aware of the fact that medical school causes a wee bit of anxiety for many of our students.)

Blood samples were drawn and the Beck Anxiety Inventory was performed on low stress days and on the day before exams.

Students receiving the omega-3 supplements had a 14% decrease in the inflammatory marker IL-6 and a 20% decrease in anxiety compared to the placebo group. While those percentages are small, that is to be expected because the incidence of both anxiety and inflammation is very low to begin with in a young, healthy population like this one. More importantly, both decreases were statistically significant.

#2) In the second study (Sinn et al, British Journal of Nutrition: doi:10.1017/S0007114511004788) 50 people over the age of 65 (average age = 74) were given either 1.8 grams of an omega-3 supplement enriched for EPA or a placebo containing an equivalent amount of the omega-6 fatty acid linoleic acid for 6 months. Depressive symptoms were assessed on the Geriatric Depression Scale.

In this study the omega-3 group had a significant decrease in depressive symptoms.

#3) In the third study (Aronson et al, Cancer Prevention Research, doi: 10.1158/1940-6207.

CAPR-11-0298) men with prostate cancer who were scheduled to undergo radical prostatectomy (an operation that removes the prostate gland and some of the surrounding tissue) were randomly assigned to receive either a low-fat diet with 5 grams of fish oil daily (an omega-6:omega-3 ration of 2:1) or a low-fat diet with 5 grams of the oils in the standard American diet (an omega-6:omega-3 ratio of 15:1) for four to six weeks prior to the operation. At the time of the operation, the number of rapidly dividing cells in the cancer tissue was determined.

The results were fairly dramatic. The tumors from the individuals receiving the omega-3 supplement had a significant reduction in the number of rapidly dividing cells. The authors considered this a highly promising result saying that "the rate at which cancer cells are dividing can be predictive of future cancer progression. The lower the rate of proliferation, the lesser the chances that the cancer will spread outside the prostate, where it is much harder to treat."

The limitations of these studies are fairly obvious.

1) They are relatively small studies and need to be replicated by larger, longer duration studies.

2) The studies are using high levels of omega-3 fatty acids, particularly the prostate cancer study. That is typical for clinical trials, which are designed to maximize the possibility of a positive outcome in a short period of time. However, it will be important to test whether lower intakes of omega-3 fatty acids over a longer period of time confer the same benefits.

The strength of these studies is that they are fully consistent with population studies showing that people with high intakes of omega-3 fatty acids are less likely to suffer from anxiety, depression and certain forms of cancer.

So what is the bottom line for you?

1) You already knew that omega-3 fatty acids reduced the risk of heart disease. The studies described above are consistent with many previous studies suggesting that omega-3 fatty acids may have many other health benefits as well.

2) The typical American diet is very low in omega-3 fatty acids (an omega-6:omega-3 ratio of 15:1), so if you are like most Americans you should be looking at how you can increase your intake of omega-3 fatty acids.

3) Many fish - and many fish oil supplements - are contaminated with heavy metals and PCBs, so you need to do your homework and chose food and supplements that are low in these contaminants.

To Your Health!

Dr. Stephen G Chaney