Vitamin D Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin D, including details on sources, melanin, benefits, deficiency, supplements, calcium absorption.

Lack of effect of calcium intake on the 25-hydroxyvitamin d response to oral vitamin D3.

Goussous R, Song L, Dallal GE, Dawson-Hughes B

Division of Endocrinology, Tufts-New England Medical Center, Boston, Massachusetts 02111, USA.

This study was conducted to examine the effect of calcium intake on the rise in serum 25-hydroxyvitamin D [25(OH)D] levels in response to supplemental vitamin D(3). Fifty-two healthy older men and women were randomly assigned to take calcium (500 mg twice daily with meals) or placebo tablets for 90 d between October 1 and the end of March. All participants were placed on 800 IU/d (20 microg/d) vitamin D(3). Serum 25(OH)D measurements were made at baseline and on d 30, 60, and 90. The mean baseline 25(OH)D values were 19.2 +/- 6.4 ng/ml (47.9 +/- 15.9 nmol/liter) in the calcium group and 19.6 +/- 6.7 ng/ml (49.1 +/- 16.7 nmol/liter) in the control group (P = 0.808). The difference in pattern of change in 25(OH)D was not statistically significant (group by time interaction, P = 0.651); the calcium group increased 6.5 +/- 5.9 ng/ml (16.2 +/- 14.8 nmol/liter; P < 0.001), and the control group increased 6.6 +/- 7.0 ng/ml (16.6 +/- 17.4 nmol/liter; P < 0.001). The 95% confidence interval for difference in mean increase, calcium vs. control, was -3.8 +/- 3.5 ng/ml (-9.6, 8.7) nmol/liter. In older men and women, the level of calcium intake, within the range of 500-1500 mg/d, does not have an important effect on the rise in serum 25(OH)D that occurs in response to 800 IU (20 microg)/d vitamin D(3).

Published 8 February 2005 in J Clin Endocrinol Metab, 90(2): 707-11.
Full-text of this article is available online (may require subscription).

© 2004-2008 Vitamin D Research Today. All Rights Reserved.