KANSAS CITY, KANSAS. Atherosclerosis is the hardening of the arteries due to plaque build-up, which can lead to heart attack or stroke. Short-term trials have concluded that fish oil supplementation has a favourable effect on several risk factors for atherosclerosis. Researchers at the University of Kansas Medical Center report the results of a 6-month study designed to determine the effect of fish oil supplementation at various dosages on cholesterol levels, triglyceride levels, bleeding time, and blood (plasma phospholipids) levels of fatty acids.
The trial involved 28 patients who had high (average 275 mg/dL) cholesterol levels and high (average 337 mg/dL) triglyceride levels. The patients were randomly assigned to receive 3, 6, 9 or 12 fish oil capsules daily for six months. Three capsules provided 1.25 grams of long-chain (20-22 carbon) omega-3 fatty acids. All trial variables were measured twice before supplementation began and then at the end of 1, 5, and 6 months of supplementation as well as after one month of washout at the conclusion of the trial.
There was no statistically significant changes in total cholesterol level among any of the groups. Triglyceride levels decreased by an overall 30% with higher fish oil intakes providing greater decreases. Low-density cholesterol (LDL) levels and high-density cholesterol (HDL) levels both increased by an overall 7% during the six-month supplementation period thus maintaining the important LDL/HDL ratio. There was no clear overall correlation between fish oil doses and bleeding time, but patients taking 6 or 12 capsules did appear to have significantly longer bleeding times. Both linoleic and arachidonic acid levels in phospholipids were reduced by all doses of fish oil. Levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) rose significantly as dosages increased. All measured variables tended to converge towards baseline values after the final one-month washout period. The researchers conclude that fish oil supplementation produces physiologically important changes which may lower the risk of cardiovascular disease.
Harris, William S., et al. Effects of four doses of n-3 fatty acids given to hyperlipidemic patients for six months. Journal of the American College of Nutrition, Vol. 10, No. 3, 1991, pp. 220-27