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Dietary calcium and blood pressure in a Native American population
K M Narayan1, R L Hanson, C J Smith
1Diabetes and Arthritis Epidemiology Section, Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Arizona, USA.
Objective:
To assess the relationship between dietary calcium and blood pressure.
Methods:
Cross-sectional study of 404 adult Pima Indians of Arizona. Dietary variables were assessed by the 24-hour recall. Hypertension (HTN) was defined as systolic blood pressure (SBP) > or = mmHg or diastolic blood pressure (DBP) > or = 90 mmHg or drug treatment.
Results:
Controlled for age and 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 men DBP in low, middle and high tertiles of calcium was 74, 76, and 79 mmHg, respectively (p < 0.001). SBP was not significantly different in the three tertiles (p = 0.07). Multiple regression analyses that controlled for age, sex, body mass index, sodium, potassium and alcohol also suggested 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 association between dietary calcium and blood pressure reported in other populations was not found.