Effect of calcium supplementation on diastolic blood pressure in young people with mild hypertension.

In a double-blind trial 90 mildly hypertensive subjects aged 16-29 years were randomly assigned to 1 g calcium per day or placebo. Calcium supplementation did not affect systolic blood pressure, but at six and twelve weeks diastolic blood pressure had fallen by 3.1 (p = 0.04) and 2.4 (p = 0.11) mm Hg, respectively, more in the calcium group than it had in the placebo group. Subjects with a baseline plasma parathyroid hormone (PTH) higher than the median showed a 6.1 mm Hg (p = 0.01) greater fall in diastolic blood pressure after six weeks and 5.4 mm Hg (p = 0.01) after twelve than in the placebo group. The fall in diastolic blood pressure was greater in the calcium group than in the placebo group in subjects with a lower than median serum total calcium and in those with a large bodyweight. Calcium supplementation may lower blood pressure in young people with mildly raised blood pressure, particularly in those with high plasma PTH and/or low serum total calcium.