title: Controlled high meat diets do not affect calcium retention or indices of bone status in healthy postmenopausal women.
abstract: Calcium balance is decreased by an increased intake of purified proteins, although the effects of common dietary sources of protein (like meat) on calcium economy remain controversial. We compared the effects of several weeks of controlled high and low meat diets on body calcium retention, using sensitive radiotracer and whole body scintillation counting methodology. Healthy postmenopausal women (n = 15) consumed diets with similar calcium content (approximately 600 mg), but either low or high in meat (12 vs. 20% of energy as protein) for 8 wk each, in a randomized crossover design. After 4 wk of equilibration of each diet, calcium retention was measured by extrinsically labeling the 2-d menu with (47)Ca, followed by whole body scintillation counting for 28 d. Urinary and blood indicators of bone metabolism were also determined for each diet. Calcium retention was not different during the high and low meat dietary periods (d 28, mean +/- pooled SD: 17.1 and 15.6%, +/-0.6%, respectively; P = 0.09). An initially higher renal acid excretion in subjects consuming the high meat compared with the low meat diet decreased significantly with time. The diets did not affect urinary calcium loss or indicators of bone metabolism. In conclusion, under controlled conditions, a high meat compared with a low meat diet for 8 wk did not affect calcium retention or biomarkers of bone metabolism in healthy postmenopausal women. Calcium retention is not reduced when subjects consume a high protein diet from common dietary sources such as meat.
authors.affiliation: Grand Forks Human Nutrition Research Center, Agricultural Research Service, U.S. Department of Agriculture, Grand Forks, ND 58202-9034, USA. froughea@gfhnrc.ars.usda.gov
authors.forename: Zamzam K
authors.initials: ZK
authors.lastname: Roughead
authors.forename: LuAnn K
authors.initials: LK
authors.lastname: Johnson
authors.forename: Glenn I
authors.initials: GI
authors.lastname: Lykken
authors.forename: Janet R
authors.initials: JR
authors.lastname: Hunt
mesh_terms: D000368:Aged; D015415:Biomarkers; D015519:Bone Density; D002118:Calcium / Q000378:metabolism*; D018592:Cross-Over Studies; D004032:Diet; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D008460:Meat; D008875:Middle Aged; D012016:Reference Values; D016482:Urinalysis
chemical_list: D015415:Biomarkers; D002118:Calcium