The Impact of Dietary Protein on Calcium Absorption and Kinetic Measures of Bone Turnover in Women

J Clin Endocrinol Metab. 2005 Jan;90(1):26-31. doi: 10.1210/jc.2004-0179. Epub 2004 Nov 16.

Abstract

Although high-protein diets induce hypercalciuria in humans, the source of the additional urinary calcium remains unclear. One hypothesis is that the high endogenous acid load of a high-protein diet is partially buffered by bone, leading to increased skeletal resorption and hypercalciuria. We used dual stable calcium isotopes to quantify the effect of a high-protein diet on calcium kinetics in women. The study consisted of 2 wk of a lead-in, well-balanced diet followed by 10 d of an experimental diet containing either moderate (1.0 g/kg) or high (2.1 g/kg) protein. Thirteen healthy women received both levels of protein in random order. Intestinal calcium absorption increased during the high-protein diet in comparison with the moderate (26.2 +/- 1.9% vs. 18.5 +/- 1.6%, P < 0.0001, mean +/- sem) as did urinary calcium (5.23 +/- 0.37 vs. 3.57 +/- 0.35 mmol/d, P < 0.0001, mean +/- sem). The high-protein diet caused a significant reduction in the fraction of urinary calcium of bone origin and a nonsignificant trend toward a reduction in the rate of bone turnover. There were no protein-induced effects on net bone balance. These data directly demonstrate that, at least in the short term, high-protein diets are not detrimental to bone.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Bone Resorption / metabolism*
  • Calcium / metabolism*
  • Dietary Proteins / administration & dosage*
  • Female
  • Humans
  • Intestinal Absorption*
  • Kinetics
  • Osteogenesis*

Substances

  • Dietary Proteins
  • Calcium