Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2004
Publication Date: 3/7/2005
Citation: Roughead, Z.K., Johnson, L.K., Lykken, G.I. 2005. A high protein intake enhances calcium retention from a low calcium diet in healthy postmenopausal women: A controlled feeding study [abstract]. The Federation of American Societies for Experimental Biology Journal. 19(5):A1463. Interpretive Summary:
Technical Abstract: Aim: To determine whether dietary protein and calcium (Ca) interact to affect Ca retention and thus bone health. Design: In a controlled feeding study with a 2x2 factorial design, healthy postmenopausal women (n=27, age: 45-69 y; BMI: 27 ± 4) were randomly assigned to either a low Ca (600 mg/d) or a high Ca (1500 mg/d) group and consumed low protein and high protein diets [10% and 20% of energy mostly as meat protein, respectively] for 7 wk each in a randomized, crossover design. After 3 wk of equilibration, the menu was labeled with 47Ca-radiotracer and its retention was monitored for 28 d by whole body counting. The retention data (% dose) were modeled by a two-component exponential model; lsmean ± SE from ANOVA are reported. Results: Regardless of Ca intake, a high protein diet increased urinary Ca and total noncarbonic acid excretion (P<0.0001). At low Ca intake, a high protein diet enhanced the initial Ca absorption (26 ± 1 to 30 ± 1, P<0.01) and the subsequent retention (day 28: 15 ± 0.9 to 17 ± 0.9, P<0.05), as compared to a low protein diet. As expected, a high Ca intake reduced the fractional Ca retention as compared to the low Ca diet (16 ± 0.8 to 10 ± 0.8, P<0.0001). A high protein intake also increased serum IGF-1 (P<0.01) and decreased bone resorption, as indicated by urinary deoxypyridinoline (P<0.01). Conclusion: In postmenopausal women, a moderately high protein diet may be beneficial to bone health, especially when Ca intake is low.