Increasing calcium intake lowers blood pressure: the literature reviewed.

Evidence to support an association between dietary calcium and blood pressure is presented in this article. Epidemiological surveys, animal experiments, and clinical trials support an inverse relationship between calcium and blood pressure. Several independent diet surveys have reported reduced consumption of calcium by individuals with hypertension. Animal experiments demonstrate an inverse correlation between calcium intake and blood pressure and reveal disturbances in calcium metabolism in hypertensive animals. Similar metabolic disturbances, including lower serum ionized calcium, elevated parathyroid hormone values, and increased urinary calcium excretion, have been reported in human hypertensives compared with normotensives. In addition, three recent experimental trials using 1 gm calcium carbonate supplements demonstrated that increasing calcium intake may reduce blood pressure in some human beings. Further clinical investigations are necessary to define the subset of patients who will respond to calcium therapy. Dietary sources of calcium to provide at least the RDA are recommended. Dairy products are suggested because in addition to calcium, they are valuable sources of potassium and magnesium, which may also lower blood pressure. If a patient cannot tolerate dairy products, oral calcium supplements are indicated.