Combined calcium and vitamin D supplementation is not superior to calcium supplementation alone in improving disturbed bone metabolism in patients with congestive heart failure

Objectives: To clarify the potential role of vitamin D supplementation on bone metabolism in congestive heart failure (CHF) patients with low vitamin D status and insufficient dietary calcium intake. Subjects/Methods: One hundred and two ambulatory male CHF patients were recruited, of whom the majority was treated with loop diuretics. Nine patients died during follow-up. Additional 14 participants dropped out prematurely because their health status worsened markedly. Five patients had to be excluded due to lack of compliance. A daily vitamin D3 supplement plus 500 mg calcium (CaD group) or a placebo plus 500 mg calcium (Ca group) was given for 9 months. Biochemical parameters of vitamin D and bone metabolism were analyzed at baseline and after 9 months. Results: Median 25-hydroxyvitamin D concentrations increased from 41.7 to 103.0 nmol/l (P < 0.001) in the CaD group and remained constant in the Ca group, while median calcium intake increased above 1200 mg/day in both groups. The percentage of patients with elevated parathyroid hormone levels (>60 pg/ml), as well as the serum concentration of undercarboxylated osteocalcin, an indicator of osteoporotic fracture risk and the bone resorption marker C-telopeptide fell significantly in both study groups (P < 0.025-0.001). At the end of the study period, biomarkers of bone turnover did not differ between groups. Conclusions: A vitamin D3 supplement of 50 mg/day has no additional beneficial effects on markers of bone metabolism in CHF patients with low initial 25-hydroxyvitamin D concentrations if an adequate daily calcium intake is guaranteed.