Japanese Men Exhibit Higher Levels of DHA/EPA and Less Atherosclerosis
Sekikawa A. et al., J. Am. Coll. Cardiol. 52:417-424, 2008.
University of Pittsburgh, Pittsburgh, Pennsylvania and Shiga University of Medical Science, Shiga, Japan
The present investigation was a population-based cross-sectional study wherein the degree of atherosclerosis in 313 Japanese men (from Shiga, Japan) were compared with 310 white American males (from Pennsylvania) and 303 Japanese-American men (from Honolulu, Hawaii). The omega-3 fatty acid status of the subjects was measured by determining the levels of the marine-based omega-3 fatty acids (predominantly as EPA+DHA) in blood serum samples by gas-liquid chromatographic analyses. The IMT (intima-media-thickness) of the carotid artery was measured by sonography (carotid scanning) via ultrasound. In addition, electron beam computed tomography was used to assess the CAC (coronary artery calcifications).
The results indicated that the lowest levels of atherosclerosis were found in the Japanese men and that the white Americans and Japanese-Americans had similar levels. In addition, the Japanese men had approximately double the levels of circulating serum levels of the marine-based omega-3 fatty acids (mean values of 9.2% of total fatty acids as compared to only 3.9 and 4.8% in the American men and Japanese-American men, respectively). The Japanese men exhibited a significant inverse relationship between the levels of marine-derived omega-3 fatty acids and the degree of IMT; no significant relationship was found between the omega-3 fatty acid levels and the prevalence of CAC in this population. After adjusting for traditional risk factors for cardiovascular disease, the inverse association in the Japanese men with the IMT remained. The authors conclude that very high levels of the marine-based omega-3 fatty acids (predominantly DHA+EPA) appear to have anti-atherogenic properties which are mediated independent of traditional risk factors for cardiovascular disease and such may contribute to the lower level of atherosclerosis in the Japanese males as studied.
Dr. Holub's Comments:
It should be pointed out that the authors estimated the approximate fish consumption in the Japanese men to average at least 100 g of fish per day beginning early in their lives. This represents actually one fish serving per day (assuming that one serving is approximately 3.5 oz of fish) which is approximately 7-10 times more than the average fish consumption in the North American adult. Furthermore, approximately 50% of North Americans do not consume fish on a weekly basis such that their average daily intake of DHA/EPA (combined) is approximately 120-140 mg/day. In contrast, the Japanese men as studied would be expected to regularly consume marine-based omega-3 fatty acids of levels approaching 800-1000 mg/day as reflected in their much higher levels of circulating DHA/EPA in their blood serum samples.