Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract only
Publication Acceptance Date: 12/1/2003
Publication Date: 3/23/2004
Citation: Roughead, Z.K., Johnson, L.K., Wagner, J.L. 2004. Effects of soy versus meat protein on calcium retention and bone biomechanical properties in ovarioectomized rats. Federation of American Societies for Experimental Biology Journal. 18:A852-A853. Interpretive Summary:
Technical Abstract: Aim: To determine the effects of diets high or low in soy versus meat proteins on calcium (Ca) retention and bone quality. Design: Ovarioectomized rats were assigned to 5 groups (n=8 each) with equal mean weights. One group was killed at baseline. In a 2x2 factorial design, the other groups were fed diets (0.2% Ca) with 10 or 20% meat or soy protein (2.28 mg aglycone/g protein) for 8 wk. After 2 wk, fasted rats received test meals labeled with 47Ca isotope. Ca retention was monitored for 10 d with a whole body counter. Results: Ca retention (mean'SE, % dose) was 28% higher from meat than the soy diets (53.3'2.8 and 38.5'2.7, respectively, P<0.001) and 18% higher in those fed the high versus low protein diets (50.3'2.7 and 41.6'2.8, respectively, P<0.05). Serum IGF-1 was unaffected by protein source, but was increased by 31% with high protein intake (P<0.05). Meat intake increased both body and femur sizes (by 10 and 5%, P<0.05); however, femur and vertebral mineral contents, volumetric densities, breaking stress, and toughness were unaffected by diet. Compared to baseline, bone density and breaking stress were similarly reduced over time in all groups. Conclusions: Neither meat nor soy protein, combined with marginal Ca intake, protected against estrogen deficiency bone loss. Compared to intact soy protein, meat intake resulted in greater Ca retention and larger body and bone size without changing the intrinsic quality of bones.