Effects of a Short-Term Vitamin D3 and Calcium Supplementation on Blood Pressure and Parathyroid Hormone Levels in Elderly Women1

Abstract

Calcium supplementation is effective in reducing blood pressure in various states of hypertension, including pregnancy-induced hypertension and preeclampsia. In addition, calcitropic hormones are associated with blood pressure. The hypothesis is that short-term therapy with calcium and vitamin D3 may improve blood pressure as well as secondary hyperparathyroidism more effectively than calcium monotherapy. The effects of 8 weeks of supplementation with vitamin D3 (cholecalciferol) and calcium on blood pressure and biochemical measures of bone metabolism were studied. The sample consisted of 148 women (mean ± sd age, 74 ± 1 yr) with a 25-hydroxycholecalciferol (25OHD3) level below 50 nmol/L. They received either 1200 mg calcium plus 800 IU vitamin D3 or 1200 mg calcium/day. We measured intact PTH, 25OHD3, 1,25-dihydroxyvitamin D3, blood pressure, and heart rate before and after treatment. Compared with calcium, supplementation with vitamin D3 and calcium resulted in an increase in serum 25OHD3 of 72% (P < 0.01), a decrease in serum PTH of 17% (P = 0.04), a decrease in systolic blood pressure (SBP) of 9.3% (P = 0.02), and a decrease in heart rate of 5.4% (P = 0.02). Sixty subjects (81%) in the vitamin D3 and calcium group compared with 35 (47%) subjects in the calcium group showed a decrease in SBP of 5 mm Hg or more (P = 0.04). No statistically significant difference was observed in the diastolic blood pressures of the calcium-treated and calcium- plus vitamin D3-treated groups (P = 0.10). Pearson coefficients of correlation between the change in PTH and the change in SBP were 0.49 (P < 0.01) for the vitamin D3 plus calcium group and 0.23 (P < 0.01) for the calcium group. A short-term supplementation with vitamin D3 and calcium is more effective in reducing SBP than calcium alone. Inadequate vitamin D3 and calcium intake could play a contributory role in the pathogenesis and progression of hypertension and cardiovascular disease in elderly women.