Differences in lipoprotein particle subclass distribution for Japanese Americans in Hawaii and Japanese in Japan: the INTERLIPID study

Background: Current data suggest that low density lipoprotein (LDL) and high density lipoprotein (HDL) subclass concentrations relate directly to the risk of coronary heart disease (CHD). Earlier Studies indicated that Japanese in Japan had lower rates of CHD than Japanese Americans in Hawaii. Rates of CHD appear to continue to be lower in Japan despite increasing cholesterol levels in Japan and decreasing CHD rates in the United States.

Objective: To provide insight into CHD rate differences.

Methods: Nuclear Magnetic Resonance (NMR) measurements of lipoprotein subclasses were used to assess lipoprotein particle concentration and size in samples from these two genetically similar populations in Japan and Hawaii.

Results: Japanese Americans had significantly higher age- and risk factor- adjusted concentrations of lipoprotein particles implicated in atherogenesis, including large very low density lipoprotein (VLDL; P < 0.001), small LDL (P < 0.001), and small HDL (women, P < 0.001; men, P < 0.01), and significantly lower concentrations of large LDL (P < 0.001) and the putative cardio-protective large HDL (P < 0.05) than Japanese in Japan. Average age- and risk factor- adjusted LDL and HDL particle sizes were also significantly (P < 0.001) smaller in Japanese Americans. Adjustment for body mass index markedly reduced the differences in some lipoprotein measures, including total LDL and large HDL particle concentrations for both genders, total VLDL particle concentration for women, and large VLDL concentration and average HDL particle size for men.

Conclusions: Differences in lipoprotein subclass distributions and lifestyle factors such as body weight may contribute to differences in CHD incidence for Japanese in Japan and Japanese Americans.