Increase in Bone Components of Rats Orally Administered Isoflovone-containing Soybean Extract (Nijiru)

Rie Ono^a,^b and Masayoshi Yamaguchi^a

^aLaboratory of Endocrinology and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan and ^bDepartment of Research and Development, Marumiya K.K., 2211 Uchida, Kikusui-machi, Tamana Gunn, Kumamoto 865-0104, Japan.

The effect of isoflavone-containing soybean extract (nijiru) administration on bone components in rats was investigated. Rats were orally administered nijiru solution (100 mg/ml/100 g body weight) twice a day for 7 and 14 d. Nijiru suspension contained saponin (66 mu g/ml), daidzin (77 mu g/ml), daidzein (0.6 mu g/ml), genistin (58 mu g/ml), and genistein (0.6 mu g/ml). The solution administered for both periods caused a significant elevation of calcium content, alkaline phosphatase activity, and deoxyribonucleic acid (DNA) content in the diaphyseal and metaphyseal tissues of the femur in rats, while administration for 14 d did not cause a significant alteration in body weight or serum calcium and inorganic phosphorus concentrations, indicating that the solution may not have a toxic effect. This study demonstrates that intake of isoflavone-containing nijiru has an anabolic effect on bone components in rats, suggesting its role in the prevention of osteoporosis.