DIETARY CALCIUM AND BLOOD-PRESSURE IN A NATIVE-AMERICAN POPULATION

Objective: To assess the relationship between dietary calcium and bloo d pressure. Methods: Cross-sectional study of 404 adult Pima Indians o f Arizona. Dietary variables were assessed by the 24-hour recall. Hype rtension (HTN) was defined as systolic blood pressure (SEP) greater th an or equal to 140 mmHg or diastolic blood pressure (DBP) greater than or equal to 90 mmHg or drug treatment. Results: Controlled for age an d sex, dietary calcium intake was higher in subjects with HTN than in those without (p<0.01), and higher dietary calcium was associated with a higher prevalence of HTN (odds ratio comparing highest with lowest tertile group of calcium=2.6, 95% CI 1.4-4.8). Age-sex-adjusted mean D BP in low, middle and high tertiles of calcium was 74, 76, and 79 mmHg , respectively (p<0.001). SEP was not significantly different in the t hree tertiles (p=0.07). Multiple regression analyses that controlled f or age, sex, body mass index, sodium, potassium and alcohol also sugge sted a positive association between DBP and dietary calcium (p<0.01), an association which was stronger at higher glucose concentrations (p< 0.01 for the calcium-glucose interaction). Conclusion: In Pima Indians , a population with a high incidence of diabetes, the inverse associat ion between dietary calcium and blood pressure reported in other popul ations was not found.