Do ethnic differences in dietary cation intake explain ethnic differences in hypertension prevalence? Results from a cross-sectional analysis

PURPOSE: To better understand how the magnitude of the association between ethnicity and hypertension is affected by ethnic differences in dietary cation intake, we describe differences in dietary cation intakes and prevalence of hypertension across four ethinic groups (African-Americans, European-Americans, Mexican-Americans, and Puerto Ricans). We also assess the cross-sectional association between: (i) hypertension and self-reported dietary intakes of sodium, potassium, and calcium for each ethnic group; and (ii) ethnicity and hypertension before and after adjustment for dietary cation intakes. METHODS: Data from the Second National Health and Nutrition Examination Survey (1976–1980) and the Hispanic Health and Nutrition Examination Survey (1982–1984) were analyzed. Multiple logistic regression was used to estimate odds ratio (OR) for hypertension for each ethnic group, with adjustment for age, body mass index (BMI), and diabetes status. Comparisons were made to assess whether the magnitude for the ethnicity ORs changed when the three nutrient variables were entered into the model. RESULTS: Mexican-American and Puerto Rican men and women showed clinically and statistically significantly higher mean intakes of the three cations than did African-American men and women, who reported clinically and statistically significantly lower mean intakes of sodium, potassium, and calcium than did European-American men and women. Mean dietary intakes of potassium and calcium were higher for normotensives than for hypertensives among all ethnic groups, except African-American and Mexican-American women. In multivariate modeling, stark differences in ORs for hypertension persisted across ethnic groups despite inclusion of the nutrient variables. CONCLUSION: In this cross-sectional study, adjustment for dietary cation intakes did not alter the magnitude of the ethnic differences in prevalence of hypertension.