Vitamin A antagonizes calcium response to vitamin D in man

J Bone Miner Res. 2001 Oct;16(10):1899-905. doi: 10.1359/jbmr.2001.16.10.1899.

Abstract

For unknown reasons, the highest incidence of osteoporosis is found in northern Europe. In these populations, the sunlight exposure is limited and the vitamin A intake is high. The interaction between vitamin A and D has been the subject of several in vitro and animal studies. We have studied the acute effects of vitamin A and D on calcium homeostasis in 9 healthy human subjects. We compared the effect of (i) 15 mg of retinyl palmitate, (ii) 2 microg of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], (iii) 15 mg of retinyl palmitate plus 2 microg of 1,25(OH)2D3, and (iv) placebo in a double-blind crossover study. The subjects took vitamin preparations at 10:00 p.m. and the following day blood samples were collected five times from 8:00 a.m. to 4:00 p.m. Serum levels of 1,25(OH)2D3 and retinyl esters increased (1.7-fold and 8.3-fold, respectively; p < 0.01). As expected, serum calcium (S-calcium) increased (2.3%; p < 0.01) and S-parathyroid hormone (PTH) decreased (-32%; p < 0.05) after 1,25(OH)2D3 intake. In contrast, retinyl palmitate intake resulted in a significant decrease in S-calcium when taken alone (-1.0%; p < 0.05) and diminished the calcium response to 1,25(OH)2D3 after the combined intake (1.4%; p < 0.01). S-PTH was unaffected by retinyl palmitate. No significant changes in serum levels of the degradation product of C-telopeptide of type I collagen (CrossLaps), or U-calcium/creatinine levels were found. In conclusion, an intake of vitamin A corresponding to about one serving of liver antagonizes the rapid intestinal calcium response to physiological levels of vitamin D in man.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Calcitriol / administration & dosage
  • Calcitriol / antagonists & inhibitors*
  • Calcitriol / blood
  • Calcium / blood*
  • Cross-Over Studies
  • Diterpenes
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Vitamin A / administration & dosage
  • Vitamin A / analogs & derivatives*
  • Vitamin A / metabolism
  • Vitamin A / pharmacology*

Substances

  • Diterpenes
  • Vitamin A
  • retinol palmitate
  • Calcitriol
  • Calcium