Dietary potassium intake and stroke mortality

Background and Purpose-An inverse relationship of dietary potassium to stro ke mortality in a small community has been previously reported. To further assess this association in a larger sample, we examined data from the first National Health and Nutrition Examination Survey (NHANES I) Epidemiologica l Follow-up Study. Methods-We analyzed baseline data during 1971-1975 and follow-up through 19 92. Dietary potassium intake, determined by 24-hour dietary recall at basel ine, was available for 9866 subjects. Stroke mortality was recorded through 1992 follow-up. Results-Mean age and dietary potassium at baseline were 55 years and 2084 m g/d; blacks reported significantly lower potassium intake than whites (1606 versus 2178 mg/24 h). During an average of 16.7 years of follow-up, there were 304 stroke deaths. For men, stratified by tertile of dietary potassium intake, age-adjusted stroke mortality rates per 1000 person-years for the lowest dietary potassium group were significantly higher than for the highe st intake group, for both whites (1.94 versus 1.17; relative risk, 1.66; 95 % CI, 1.32 to 2.14) and blacks (5.08 versus 1.19; relative risk, 4.27; 95% CI, 1.88 to 9.19). For women, there was no significant difference in stroke mortality between similar levels of potassium intake for either whites (1. 61 versus 1.42; relative risk, 1.13; 95% CI, 0.84 to 1.66) or blacks (2.46 versus 3.04; relative risk, 0.80; 95% CI, 0.21 to 2.01). After stratificati on by hypertensive status, stroke mortality rates were significantly differ ent by tertile of dietary potassium only for hypertensive men. There was no stroke mortality difference by potassium intake among hypertensive women o r nonhypertensive men and women. Multivariate analysis, in which we control led for caloric intake and other baseline cardiovascular risk factors, reve aled that only among black men and hypertensive men was lower dietary potas sium intake a predictor of stroke mortality. Conclusions-The previous finding of an association of increasing dietary po tassium intake with decreasing stroke mortality has been detected only amon g black men and hypertensive men in this study.