Serum fatty acid composition in normal Japanese and its relationship with dietary fish and vegetable oil contents and blood lipid levels.

A survey was conducted on 110 normal Japanese adults (55 men and 55 women) to determine their caloric intake, dietary fat content and its origin (animal, plant, or marine). In addition, their blood lipid levels and fatty acid compositions were examined. Men in their 30s-50s consumed 2,600-2,800 calories and 60 g of fats, while women in the same age range consumed 2,000-2,200 calories and 52-58 g of fats. In both sexes, caloric, fat, and cholesterol intakes were lower for those in their 60s but protein and crude fiber consumption remained generally unchanged. When the dietary fats were classified according to origin, men and women in their 30s were found to consume less oil of marine origin. This appeared to be the result of a western style diet for Japanese adults in their 30s. Compared with men, women exhibited lower blood lipid levels. As age increased, the total cholesterol level of the blood rose in women. Thus the blood lipid level was generally equal in the two groups in their 60s. There was a positive correlation between the blood eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels and dietary consumption of fish oil. The marine/plant lipid ratio was positively correlated with the blood EPA/arachidonic acid ratio. Therefore, it was believed that the origin of the dietary fats consumed is a factor in determining the blood fatty acid profile. The linoleic acid (18:2), arachidonic acid (20:4), and 18:2 + 20:4 contents were negatively correlated to the total cholesterol level in the blood but positively correlated to the HDL-cholesterol level. Polyunsaturated fatty acids (18:2 + 20:4 + 20:5 + 22:6) were negatively correlated with the blood triglyceride level. From the findings presented above, we concluded that dietary fats not derived from animal sources should be classified into fish and vegetable oils to evaluate their dietary significance. We also noted that Japanese in their 30s consume less fish oil, indicating the western trend in their dietary lipid consumption.