Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Proceedings
Publication Acceptance Date: January 20, 2001
Publication Date: March 31, 2001
Citation: WONG, W.W., ELLIS, K.J., JAHOOR, F. SOY ISOFLAVONES MAY STIMULATE NITRIC OXIDE PRODUCTION AND REDUCE LUMBAR SPINE BONE LOSS IN POSTMENOPAUSAL WOMEN. JOURNAL OF FEDERATION OF AMERICAN SOCIETIES FOR EXPERIMENTAL BIOLOGY. 2001. v. 15(5). p. A1088. Technical Abstract: Cardiovascular disease and osteoporosis are two major health risks associated with menopause. Nitric oxide (NO) has been shown to regulate vascular smooth muscle relaxation and bone resorption. To determine if soy protein and/or soy isoflavones can stimulate NO production and reduce lumbar spine bone loss, urinary nitrate (NO3) excretion rates were measured in three groups (N=6 per group) of postmenopausal women before and after 6-wk of therapy with either: 40g/d of soy protein with negligible isoflavone content (group 1); or 40 g/d of soy protein with 90 mg/d of isoflavone (group 2); or 160 mg/d of isoflavones (group 3). Lumbar spine bone mineral content (BMC) and density (BMD) of these women were measured before therapy and after 1 y of habitual diet (Groups 1 and 2, N=11) or 1 y of isoflavone therapy (Group 3, N=5). After 6 wk of treatment urinary NO3 excretion was reduced by 13±12% (mean±SE) in Group 1 but increased by 10±18% in Group 2 and 20±18% in Group 3. Increases in lumbar spine BMC and BMD of 2.5%y and 2.0%y, respectively, were observed in the 5 women receiving 1 y of isoflavone therapy. Decreases in lumbar spine BMC and BMD of 2.9%y and 0.6%y were observed in the 11 women who returned to their habitual diets. Although the changes in urinary NO3 excretion and lumbar spine BMC and BMD were not statistically significant, the changes were in the direction suggesting that soy isoflavone therapy may stimulate NO production and reduce lumbar spine bone loss in postmenopausal women.