Dietary soybean protein prevents bone loss in an ovariectomized rat model of osteoporosis.Author: Arjmandi BH et all. Publication: J Nutr. 1996 Jan;126(1):161-7.
The purpose of this investigate whether soybean protein isolate could prevent bone loss in rats which had a deficiency of estrogen hormones.
A total of 32 rats were divided in 4 groups:
Group 1: sham-operated rats receiving casein
Group 2: ovariectomized rats receiving casein
Group 3: ovariectomized rats receiving soybean isolate
Group 4: ovariectomized rats receiving 17 beta-estradiol and casein
The rats were examined after 30 days.
All rats received casein as protein source except group 3 which received soybean isolate.
The following results were obtained. Rats from group 2 had a had significantly lower densities of the right femur and the fourth lumbar vertebra than rats in the sham group, which can be explained by the low natural estrogen levels. Rats from group 3 and group 4 had same bone densities as group 1. These results suggest that that dietary soybean protein is effective in preventing bone loss in situations with ovarian hormone deficiency.
The vertebral and femoral bone densities of the rats from group 3 were significantly greater than those of rats in group 2, indicating that the formation of bone exceeds the resorption. From this study it can not be concluded whether these positive results of soybean protein is coming from the protein itself or from the isoflavones.Dietary isoflavones: biological effects and relevance to human health. J Nutr. 1999 Mar;129(3):758S-767S