Nutraceuticals: Calcium & Vitamin D
Indication: Bone Turnover
Source: Journal of Clinical Endocrinology & Metabolism, Sep. 24, 2013 (epub ahead of print)

Research: Bone health is influenced by the intake of both calcium and vitamin D. The objective for this study was to evaluate the influence of calcium and vitamin D supplementation on serum parathyroid hormone (PTH) and bone turnover. At an ambulatory research center, 159 healthy, postmenopausal, white women participated in this double-blind, placebo-controlled parallel, longitudinal factorial study that began in December 2008 and ended in April 2011. It was 6 months in duration.

Subjects were randomly allocated to 4 groups: double placebo, calcium (1,200 mg daily) plus placebo, vitamin D3 (100 μg) plus placebo and vitamin D3 and calcium. Serum and urine were collected fasting and 2 hours after a calcium load at baseline and at 3 and 6 months. Serum PTH, cross-linked C-telopeptide (CTX) and procollagen type I N-terminal propeptide (P1NP) were measured.

Results: Before study medication, a calcium load resulted in a decline in PTH and CTX and an increase in urinary calcium excretion. Serum CTX and P1NP declined over time with calcium supplementation but did not change with increased vitamin D intake. There was a decline in PTH in the vitamin D groups in the fasting state compared with placebo. Suppression of PTH was greater after a calcium load in the vitamin D groups. A calcium load decreased PTH and CTX and raised urinary calcium.

Researchers concluded that fasting PTH declines with vitamin D supplementation; PTH declines after calcium intake. Supplementation of the diet with 1,200 mg calcium/day reduced bone turnover markers, whereas supplementation with up to 100 μg vitamin D3/day did not.