Serum sialic acid and its correlates in community samples from Akita, Japan and Minneapolis, USA

Objective. The concentration of serum total sialic acid (S-TSA) is one recently investigated risk marker for cardiovascular mortality and atherosclerosis. Since the mortality from coronary heart disease is higher in the United States than in Japan, one could expect the S-TSA to be higher among Caucasian US citizens than among Japanese citizens, a hypothesis that is tested in this study. Design. Cross-sectional study of population-based samples of Japanese and US Caucasian men and women, Setting. The rural community Akita, Japan, and the suburbs of Minneapolis, Minnesota. Subjects. These were 75 consecutive men and women from Akita and Minneapolis respectively aged 47-69 years in 1990. People who had smoked cigarettes during the past 5 years; who had a history of diabetes mellitus, liver disease, coronary heart disease, or stroke; or who were taking anticoagulants were excluded, Outcome Measures. Serum total sialic acid levels in male and female Japanese and US Caucasian subjects with adjustment for age, systolic blood pressure, fibrinogen, triglycerides and in women also for menopausal status. Race and sex-specific correlations with serum total sialic acid for selected cardiovascular risk markers. Results. The entire sialic acid distributions were shifted to the right in Caucasian men and women compared to Japanese men and women. The mean +/- standard deviation concentrations of S-TSA were 54.1 +/- 5.3 mg/dl in Japanese men and 58.7 +/- 5.6 mg/dl in Caucasian men (P < 0.001), In women, the concentrations were 54.8 +/- 5.1 and 63.1 +/- 6.0 mg/dl respectively (P < 0.001). S-TSA level correlated significantly and positively with fibrinogen levels in Caucasian and Japanese men and women and with triglyceride levels in Caucasian and Japanese men and in Caucasian women but not in Japanese women. After adjustment for age, systolic blood pressure, fibrinogen, triglycerides and menopausal status, the sialic acid levels were 2.2 (P = 0.009) and 6.2 (P < 0.001) mg/dl higher in Caucasian compared to Japanese men and women respectively. Conclusions. Higher S-TSA levels in Caucasians living in Minneapolis compared to Japanese living in Akita, Japan is in concordance with the higher cardiovascular mortality in the US, Differences in S-TSA levels may reflect international differences in the prevalence of atherosclerosis.