Effects of dietary calcium from dairy products on ambulatory blood pressure in hypertensive men.

The effect of consumption of 400 mg vs 1,500 mg of dietary calcium per day was examined in 13 male volunteers who had been diagnosed as hypertensive. Dietary calcium consumption was varied by manipulation of the intake of dairy products over 4-week periods. Caffeine intake (mean = 500 mg/day) was monitored. Neither laboratory blood pressure measured by standard sphygmomanometry nor ambulatory blood pressure monitored by automated sphygmomanometry varied significantly among men consuming baseline, low-calcium, or high-calcium diets (laboratory blood pressure = 136/83, 133/83, and 137/84 mm Hg, respectively; ambulatory blood pressure = 136/86, 138/87, and 138/87 mm Hg, respectively). Serum ionized calcium values did not vary with the three diets (1.25, 1.26, and 1.25 mmol/L, respectively). The parathyroid hormone level decreased (39 mmol/L vs 37 mmol/L) and the urinary calcium:creatinine ratio was elevated (0.41 vs 0.50) in the high-calcium diet. Consumption of a diet containing 1,500 mg calcium per day over 4 weeks did not produce a significant decrease in blood pressure or alterations in calcium metabolic indexes.