Background and purpose: Recent studies reported the differential effect of docosahexaenoic (DHA) and eicosapentaenoic acids (EPA). We examined the differential association of DHA and EPA with carotid intima-media thickness (IMT) in Japanese individuals in Japan and in U.S. white individuals and explored whether DHA or EPA contributes to the difference in IMT between the two groups.
Methods: A population-based cross-sectional study in 608 Japanese and U.S. white men aged 40 to 49 was conducted to assess IMT, serum DHA, EPA, and other cardiovascular risk factors.
Results: Japanese compared to U.S. whites had significantly lower IMT (mean±SD, 618±81 and 672±94 μm for Japanese and whites, respectively; P<0.001) and had >2-fold higher levels of DHA and EPA. DHA, but not EPA, had an inverse association with IMT in both Japanese and U.S. whites. The inverse association remained only in Japanese men after adjusting for risk and other factors. The significant difference in multivariable-adjusted IMT became nonsignificant after further adjusting for DHA (mean difference, 17 μm; 95% CI, -8 to 43; P=0.177) but not EPA. In this multivariable-adjusted model, DHA but not EPA was a significant predictor of IMT (P=-0.032 versus 0.863, respectively).
Conclusions: These data suggest that DHA may have a more potent antiatherogenic effect than EPA, especially in levels observed in the Japanese, independent of risk factors.