Dietary potassium intake and stroke mortality

Background and Purpose-An inverse relationship of dietary potassium to stroke 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) Epidemiological Follow-up Study. Methods-We analyzed baseline data during 1971-1975 and follow-up through 1992. Dietary potassium intake, determined by 24-hour dietary recall at baseline, 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 mg/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 highest 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 stratification by hypertensive status, stroke mortality rates were significantly different by tertile of dietary potassium only for hypertensive men. There was no stroke mortality difference by potassium intake among hypertensive women or nonhypertensive men and women. Multivariate analysis, in which we controlled for caloric intake and other baseline cardiovascular risk factors, revealed that only among black men and hypertensive men was lower dietary potassium intake a predictor of stroke mortality. Conclusions-The previous finding of an association of increasing dietary potassium intake with decreasing stroke mortality has been detected only among black men and hypertensive men in this study.