Administration of dietary fish oil capsules in healthy middle-aged Japanese men with a high level of fish consumption.

The nutritional effects of fish oil, which is rich in the n-3 polyunsaturated fatty acids, have been reported. In this randomized, placebo-controlled, double-blind, crossover study, we evaluated the effects of dietary fish oil capsules on the hematological parameters of healthy middle-aged Japanese men with a high level of fish oil consumption. Over a 4-week period, subjects were administered five fish oil or olive oil (placebo) capsules with every meal (1,260 mg eicosapentaenoic acid and 540 mg docosahexaenoic acid/day). There was a 4-week washout period between the treatment phases. The results did not demonstrate a decrease in plasma triacylglycerol, cholesterol, low-density lipoprotein cholesterol, and whole-blood viscosity. Further, no changes in the fatty acid composition of plasma and erythrocyte phospholipids were noted. These results suggested that the supplementation of fish oil might be effective only for those subjects who have a lower level of fish oil consumption.