Osteoporosis and the Role of Soybeans in Ovariectomized ( OVX) Female Albino Rats

Menopause drastically increases the risk of osteoporosis. Aside from drug therapy, lifestyle and nutritional factors play an important role in the maintenance of skeletal health. The objective of this study was to investigate the effects of soybean on bone health, and to discuss the role of soybean isoflavones on osteoporosis in ovariectomized (OVX) rats. A total of 105 female Wister albino rats having an average weight of 140-150 gm were used. They were divided into three control and three treated groups. The three control groups were: normal control, sham operated control (positive control) and OVX control (negative control), each group consisted of 20 animals. The treated groups, 15 animals each, received soybean (30, 60, 90 gm/70kg/human b.w ) which corresponds to the three doses ( 60, 120, 190 mg/145 gm rat b.w ) daily, then were left on AIN-93M diet and fresh water adlibitum for three months Compared to OVX-control group, OVX female rats fed on soybean showed significant increase in femur bone weight, femur bone Ca++ and serum Ca++. This was accompanied with a decrease in serum PTH. There were little differences in serum total E2 in the three treated groups. Free T3 and free T4 decreased but Serum TSH significantly increased in in OVX female rats fed only on 190 gm soybean/145 gm rat b.w . These results may indicate that soybean may have adverse effects on bone health and thyroid gland function resulting in the suppression of thyroid hormone synthesis in ovariectomized female albino rats.