Search National Agricultural Library Digital Collections

NALDC Record Details:

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

Permanent URL:
http://handle.nal.usda.gov/10113/58217
File:
Download [PDF File]
Abstract:
Objective: The objective was to determine the effects of high dietary protein (mostly meat) and high potential renal acid load (PRAL) on calcium (Ca) balance and markers of bone metabolism. Methods: In a randomized crossover design, sixteen healthy postmenopausal women consumed two diets: one with low protein and low PRAL (LPLP; total protein: 61 g/d with meat protein: 12 g/d; PRAL: -48 mEq/d) and one with high protein (HPHP; total protein: 118 g/d with meat protein: 68g/d; PRAL: 33 mEq/d) for 7 wk each, separated by a one-wk break. After 3 wk dietary equilibration, the entire 2-d menu of each diet was radio-labeled with 47Ca and Ca absorption was measured by whole body scintillation counting for an additional 4 wk. Biomarkers of bone metabolism in blood and urine were measured. Results: Compared with the LPLP diet, the HPHP diet increased urinary acidity (mean ± pooled SD: pH 7.1 vs. 5.9 ± 0.2, p < 0.0001), urinary Ca excretion (156 vs. 203 ± 63 mg/d, p = 0.003), and blood IGF-I levels [geometric mean ± 1 pooled SD: 137 (114 – 164) vs. 175 (146 – 210) ng/ml, P < 0.0001], and decreased blood intact PTH levels [geometric mean ± 1 pooled SD: 59 (48 – 70) vs. 48 (40 – 57) ng/ml, P < 0.001] consistently throughout the study. In comparison to the LPLP diet, the HPHP diet increased subjects’ fractional Ca absorption (25.4 vs. 30.4 ± 5.4%, respectively, p < 0.02) and tended to increase the absolute amount of Ca absorbed (227 vs. 258 ± 47 mg/d, P < 0.08). The net difference between Ca absorbed and renal excretion was not significant between the LPLP and HPHP diets (82 vs. 59 ± 100 mg/d for the LPLP and the HPHP diets, respectively; P = 0.26). Conclusions: In healthy postmenopausal women, a diet high in both meat protein and potential renal acid load increased Ca absorption which counteracted the increase in urinary Ca excretion. The increased serum IGF-I combined with decreased serum PTH concentrations, with no change in biomarkers of bone resorption suggest a positive effect of a high protein diet on bone health. (This study was registered at ClinicalTrials.gov. number: NCT00620763.)
Author(s):
Jay J. Cao , LuAnn K. Johnson , Janet R. Hunt
Subject(s):
absorption , acidity , biomarkers , blood , bone resorption , calcium , excretion , high protein diet , insulin-like growth factor I , intestinal absorption , meat , meat consumption , meat protein , nutrient uptake , pH , parathyroid hormone , protein intake , urine , women
Source:
Journal of nutrition 2011 v.141
Language:
English
Year:
2011
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.