An INTERSALT study investigation: relationship between body mass index and blood pressure in the combined populations of three local centres in Japan.

Body mass index was positively and strongly correlated with BP in the INTERSALT study. Because the average body mass index in Japan, although low relative to other developed countries, has been increasing recently it would be useful, particularly from the public health viewpoint, to investigate the impact of body mass index on BP in Japanese populations. In this study, the relationship between body mass index and BP was investigated taking into account age, alcohol intake and sodium and potassium excretion in 24h urine. Data were obtained from 274 men and 284 women, aged 20-59 years, who were not taking antihypertensive medication. Random selection of participants took place at three local centres as outlined in the 1985 INTERSALT study in Japan. It was found that body mass index was positively and significantly correlated with BP in men and women, respectively, but was independent of age, alcohol intake and urinary sodium/potassium ratio. Both SBP and DBP were significantly higher by > or = 5 mmHg in participants whose body mass index (kg/m2) was in the highest quartile compared with participants in the lowest or the next lowest quartile category in men and women. In this study, it was suggested that the body mass index in Japanese men and women was directly correlated with BP independent of other confounding factors. Accordingly, the maintenance of a moderate body mass index may be important in achieving and maintaining a desirable BP level.