Scientists at Iowa State University, working with a Japanese laboratory, have determined that soy isoflavones can reduce bone loss in perimenopausal women -- women in the menopausal transition -- who otherwise could be expected to lose two to three percent of bone annually.The researchers said no previous published studies have directly examined the effect of soy protein with isoflavones on bone or, "bone turnover in perimenopausal women."In the new study conducted by five scientists at the university in Ames, Iowa, with one scientist from a commercial laboratory in Kobe, Japan, female test subjects were given 80.4 milligrams of soy protein isolate with isoflavones daily for a period of 24 weeks. Median age of the women was 50.6 years.The study, published in the American Journal of Clinical Nutrition, concluded: "Our positive results...suggest that dietary isoflavones may be effective in preventing vertebral bone loss...""The results of this study suggest that isoflavones attenuated bone loss from the lumbar spine in estrogen-deficient perimenopausal women," the researchers said, "who may otherwise be expected to lose 2-3% of bone/y" or yearly."This attenuation of loss, particularly if continued throughout the post- menopausal period, could translate into a decrease in lifetime risk of osteoporosis," the study found.The women tested were assigned to separate groups, with one receiving isoflavone-rich soy, another isoflavone-poor soy, and a control group that received whey protein, "with the isoflavone-rich treatment contributing significantly to bone mass.""Thus it is possible that the inclusion of isoflavone-containing soy products in the diets of perimenopausal women could serve as an alternative or adjunct treatment for women at risk of osteoporosis," the study said.The researchers said this may be especially important for women who are poor candidates for hormone replacement therapy. They called for a long-term study to corroborate their findings.