A diet high in meat protein and potential renal acid load increases fractional calcium absorption and urinary calcium excretion without affecting markers of bone resorption or formation in postmenopausal women

J Nutr. 2011 Mar;141(3):391-7. doi: 10.3945/jn.110.129361. Epub 2011 Jan 19.

Abstract

Our objective in this study was to determine the effects of a high-protein and high-potential renal acid load (PRAL) diet on calcium (Ca) absorption and retention and markers of bone metabolism. In a randomized crossover design, 16 postmenopausal women consumed 2 diets: 1 with low protein and low PRAL (LPLP; total protein: 61 g/d; PRAL: -48 mEq/d) and 1 with high protein and high PRAL (HPHP; total protein: 118 g/d; PRAL: 33 mEq/d) for 7 wk each separated by a 1-wk break. Ca absorption was measured by whole body scintillation counting of radio-labeled (47)Ca. Compared with the LPLP diet, the HPHP diet increased participants' serum IGF-I concentrations (P < 0.0001), decreased serum intact PTH concentrations (P < 0.001), and increased fractional (47)Ca absorption (mean ± pooled SD: 22.3 vs. 26.5 ± 5.4%; P < 0.05) and urinary Ca excretion (156 vs. 203 ± 63 mg/d; P = 0.005). The net difference between the amount of Ca absorbed and excreted in urine did not differ between 2 diet periods (55 vs. 28 ± 51 mg/d). The dietary treatments did not affect other markers of bone metabolism. In summary, a diet high in protein and PRAL increases the fractional absorption of dietary Ca, which partially compensates for increased urinary Ca, in postmenopausal women. The increased IGF-I and decreased PTH concentrations in serum, with no change in biomarkers of bone resorption or formation, indicate a high-protein diet has no adverse effects on bone health.

Trial registration: ClinicalTrials.gov NCT00620763.

Publication types

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

MeSH terms

  • Aged
  • Biomarkers / blood
  • Biomarkers / urine
  • Bone Resorption / prevention & control*
  • Bone and Bones / metabolism
  • Calcium / blood
  • Calcium / metabolism*
  • Calcium / urine*
  • Calcium Radioisotopes
  • Cross-Over Studies
  • Dietary Proteins / adverse effects
  • Dietary Proteins / therapeutic use*
  • Female
  • Humans
  • Insulin-Like Growth Factor I / analysis
  • Intestinal Absorption
  • Meat* / adverse effects
  • Middle Aged
  • Osteogenesis*
  • Osteoporosis, Postmenopausal / blood
  • Osteoporosis, Postmenopausal / metabolism
  • Osteoporosis, Postmenopausal / prevention & control*
  • Osteoporosis, Postmenopausal / urine
  • Parathyroid Hormone / blood
  • Whole-Body Counting

Substances

  • Biomarkers
  • Calcium Radioisotopes
  • Dietary Proteins
  • PTH protein, human
  • Parathyroid Hormone
  • Insulin-Like Growth Factor I
  • Calcium

Associated data

  • ClinicalTrials.gov/NCT00620763