Inclusion of 95 % range in the model to account for inter-individual variability increased the predicted intake of vitamin D needed to maintain serum 25(OH)D ≥ 50 nmol/l to 930 IU/d .
Effects of a short-term vitamin D(3) and calcium supplementation on blood pressure and parathyroid hormone levels in elderly women.
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 D(3 ) may improve blood pressure as well as secondary hyperparathyroidism more effectively than calcium monotherapy . The effects of 8 weeks of supplementation with vitamin D(3 ) ( 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 ( 25OHD(3 ) ) level below 50 nmol/L. They received either 1200 mg calcium plus 800 IU vitamin D(3 ) or 1200 mg calcium/day . We measured intact PTH , 25OHD(3 ) , 1,25-dihydroxyvitamin D(3 ) , blood pressure , and heart rate before and after treatment . Compared with calcium , supplementation with vitamin D(3 ) and calcium result ed in an increase in serum 25OHD(3 ) 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 D(3 ) 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 D(3)-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 D(3 ) plus calcium group and 0.23 ( P < 0.01 ) for the calcium group . A short-term supplementation with vitamin D(3 ) and calcium is more effective in reducing SBP than calcium alone . Inadequate vitamin D(3 ) and calcium intake could play a contributory role in the pathogenesis and progression of hypertension and cardiovascular disease in elderly women
Inclusion of 95 % range in the model to account for inter-individual variability increased the predicted intake of vitamin D needed to maintain serum 25(OH)D ≥ 50 nmol/l to 930 IU/d .