Calcium intake and the relationship of dietary sodium and potassium to blood pressure.

Using First National Health and Nutrition Examination Survey (NHANES I) data, we studied the relationships of dietary sodium, potassium, and alcohol to blood pressure in relation to levels of dietary calcium intake. At low Ca intakes (less than 400 mg/d for men and less than 800 mg/d for women) the ratio of Na to K (Na:K) was significantly related to blood pressure (p less than 0.01) after controlling for age, body mass index (BMI), race, and gender. At higher Ca intakes neither Na:K nor any other nutrient (with the exception of alcohol) was related to either systolic or diastolic blood pressures. Na:K was more strongly related to blood pressure than either nutrient alone and low Ca intakes were necessary for the Na:K-blood pressure relationship to be evident. Interaction of these three dietary factors in relation to blood pressure was evident in all race and gender groups. Associations of age, BMI, gender, and alcohol with blood pressure were not affected by Ca levels.