Epidemiological Studies of Hypertension Among Elderly Japanese and Japanese Americans

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Abstract
A prospective international study of cardiovascular disease among Japanese men living in Japan, Hawaii and California in 1965 provided the opportunity of comparing the levels of blood pressure and hypertension among men aged 45 to 68 years, and of examining the factors which accounted for the differences. In addition, within the group of 8, 006 men from Hawaii, a subsample of men were examined 15 years later when they were aged 60 to 80 to study the influence of migration, the stressful aspects of culture change, diet, life-style, Type A behaviour and biological characteristics for association with blood pressure and as predictors of hypertension. At the initial examination, the men in California had the highest levels of blood pressure and hypertension, the men in Japan had the lowest levels, and the men born in Hawaii had intermediate levels. When blood pressure was adjusted for relative weight, the differences among the groups disappeared. Within the Hawaii cohort, bivariate and multivariate analyses of more than 50 variables indicated that age, obesity, alcohol intake, serum glucose and parental history of hypertension were the major variables independently associated with cross-sectional levels of blood pressure and, except for alcohol intake, with longitudinal changes in blood pressure. Reported dietary intake of calcium, magnesium, potassium, protein and other nutrients were all inversely associated with blood pressure levels. The intake of those nutrients was so highly correlated with each other that it was not possible to identify the independent association of any single dietary factor. The results suggested that the foods which are major sources of the nutrients (vegetables, fruits, whole grains and low fat dairy products) may be protective against hypertension. Blood pressure was not associated with salt, or salty Japanese foods, either in the international comparisons or in the group from Hawaii. Among the psychosocial factors, there was no evidence that measures of theoretically stressful social situations, social support or the Jenkins measure of Type A personality were associated with blood pressure within the Hawaiian group. From the perspective of prevention of hypertension in the elderly, these data suggest that obesity, alcohol intake and low intake of minerals found in fruits, vegetables and whole grains are the factors which should receive primary consideration.