Fish Oil and Atherosclerosis
The epidemiologic observation that populations which consume substantial quantities of omega-3 fatty acids may have a reduced prevalence of atherothrom-botic cardiovascular disorders led investigators to study the potential inhibitory effects of omega-3 fatty acids on atherogenesis in animals. Weiner et al studied the effects of dietary omega-3 fatty acid supplementation on the extent of coronary artery atherosclerosis in a hyperlipidemic swine model. They observed a significant reduction in coronary atherosclerosis, even though plasma lipid levels were not significantly different in the treated animals and controls. Davis et al assessed the effects of dietary substitution of omega-3 fatty acids for coconut oil in a rhesus monkey atherosclerosis model. more
A substantial reduction in aortic atherosclerosis was observed in the groups receiving omega-3 fatty acid feeding compared with controls who received dietary fat via coconut oil. In this experiment, a substantial reduction in serum total and LDL cholesterol was seen in the fish oil treated groups, but total cholesterol was still elevated, at —400 mg/dl. The rhesus monkeys in this experiment received 10 times the amount of omega-3 fatty acids per day (ie, mg/kg body weight) than did the animals in the swine study, which may explain the differences in lipid values between the two experiments.
Hollander et al in a preliminary report have suggested that dietary fish oil supplementation significantly reduced the extent of coronary, aortic, and common carotid atherosclerosis in cynomologus monkeys without significant changes in serum lipid measurements. However, they did observe a focal increase in atherosclerotic lesions at the carotid bifurcation.
These beneficial effects of dietary omega-3 fatty acids on atherogenesis have not been observed in rabbit atherosclerosis models. Surprisingly, Thiery and Seidel, noted an increase in the extent of atherosclerosis in their rabbits receiving omega-3 fatty acids. The rabbit is exquisitely sensitive to dietary cholesterol, and the animals in this study had circulating plasma cholesterol levels of over 1,600 mg/dl.