Racial differences in blood pressure in evans county, Georgia: Relationship to sodium and potassium intake and plasma renin activity

Abstract

To investigate the hypothesis that the higher prevalence of hypertension in blacks may be related to a greater dietary intake of sodium, we studied the relationship between race, blood pressure, estimates of dietary sodium and potassium intake, and plasma renin activity (PRA), in two population samples from Evans County, Georgia. In the first random sample obtained in 1961, dietary electrolyte intake was estimated by duplicate dietary collections and simultaneous 24-hr urine collections. In the second sample obtained in 1968, a single-morning urine specimen was obtained and PRA was measured in each subject. The data demonstrate that blacks and whites ingested similar quantities of sodium, but that the dietary potassium intake of blacks was consistently less than that of whites. Blacks had higher blood pressures than whites and a greater prevalence of individuals with diastolic blood pressures >90 mmHg. PRA was inversely correlated with age, blood pressure and estimates of sodium intake. The higher blood pressures and higher prevalence of hypertension in blacks does not appear to be a function of a greater dietary sodium intake in blacks. However, an increased susceptibility to the hypertensinogenic effects of sodium in blacks remains a possibility.