KANSAS CITY, MISSOURI. Dr. William S. Harris of the Mid America Heart Institute has released a comprehensive study of the results of 68 major clinical trials aimed at determining the effects of fish oil supplementation on cholesterol and triglyceride levels.
The studies included over 2800 participants, lasted from 2 to 52 weeks, and involved supplementation with around 10 grams/day of fish oils. The participants received either fish oil or placebo (mostly olive oil) and included people with normal as well as people with elevated cholesterol and triglyceride levels. Based on the results of the studies Dr. Harris concludes that fish oil supplementation lowers blood levels of triglycerides by about 25-30%; he points out that this is equivalent to the effect obtained by taking the drug gemfibrozil. Fish oils tend to increase the levels of low-density cholesterol (LDL) by about 5-10%, but has little effect on high-density cholesterol (HDL) levels. Overall cholesterol levels are not affected by fish oil supplementation. Dr. Harris emphasizes that the triglyceride-reducing effect is unique to long-chain omega-3 acids found in fish oils. The shorter chain omega-3 oil, alpha-linolenic acid (found in flaxseed oil) has no effect on triglyceride or cholesterol levels.
Harris, William S. n-3 fatty acids and serum lipoproteins: human studies. American Journal of Clinical Nutrition, Vol. 65 (suppl), 1997, pp. 1645S-54S [83 references]