The Effect of Dietary Omega-3 Fatty Acids on Coronary Atherosclerosis. A Randomized, Double-blind, Placebo-controlled Trial

Background: Epidemiologic studies, studies of mechanisms of action, and many animal studies indicate that dietary intake of omega-3 fatty acids has antiatherosclerotic potential. Few trials in humans have examined this potential.

Objective: To determine the effect of dietary intake of omega-3 fatty acids on the course of coronary artery atherosclerosis in humans.

Design: Randomized, double-blind, placebo-controlled, clinically controlled trial.

Setting: University preventive cardiology unit.

Patients: 223 patients with angiographically proven coronary artery disease.

Intervention: Fish oil concentrate (55% eicosapentaenoic and docosahexaenoic acids) or a placebo with a fatty acid composition resembling that of the average European diet, 6 g/d for 3 months and then 3 g/d for 21 months.

Measurements: The results of standardized coronary angiography, done before and after 2 years of treatment, were evaluated by an expert panel (primary end point) and by quantitative coronary angiography. Patients were followed for clinical and laboratory status.

Results: Pairs of angiograms (one taken at baseline and one taken at 2 years) were evaluated for 80 of 112 placebo recipients and 82 of 111 fish oil recipients. At the end of treatment, 48 coronary segments in the placebo group showed changes (36 showed mild progression, 5 showed moderate progression, and 7 showed mild regression) and 55 coronary segments in the fish oil group showed changes (35 showed mild progression, 4 showed moderate progression, 14 showed mild regression, and 2 showed moderate regression) (P = 0.041). Loss in minimal luminal diameter, as assessed by quantitative coronary angiography, was somewhat less in the fish oil group (P > 0.1). Fish oil recipients had fewer cardiovascular events (P = 0.10); other clinical variables did not differ between the study groups. Low-density lipoprotein cholesterol levels tended to be greater in the fish oil group.

Conclusion: Dietary intake of omega-3 fatty acids modestly mitigates the course of coronary atherosclerosis in humans.