Arjmandi B H, Birnbaum R, Goyal N V, Getlinger M J, Juma S, Alekel L, Hasler C M, Drum M L, Hollis B W, Kukreja S C
Department of Nutritional Sciences, Oklahoma State University, Stillwater 74078-6141, USA.
Am J Clin Nutr. 1998 Dec;68(6 Suppl):1364S-1368S. doi: 10.1093/ajcn/68.6.1364S.
Our previous studies showed that a soy-protein diet prevents ovariectomy-induced bone loss. The purpose of this study was to determine whether isoflavones in soy protein are responsible for this bone-protective effect. Forty-eight 95-d-old Sprague-Dawley rats were divided into 4 groups: sham-operated fed a casein-based diet (SHAM), ovariectomized fed a casein-based diet (OVX+CASEIN), ovariectomized fed soy protein with normal isoflavone content (OVX+SOY), and ovariectomized fed soy protein with reduced isoflavone content (OVX+SOY-). The OVX+SOY group had significantly greater femoral bone density (in g/cm3 bone vol) than the OVX+CASEIN group, whereas OVX+SOY- was similar to OVX+CASEIN (mean +/- SD; SHAM, 1.522 +/- 0.041; OVX+CASEIN, 1.449 +/- 0.044; OVX+SOY, 1.497 +/- 0.030; OVX+SOY-, 1.452 +/- 0.030). Ovariectomy resulted in greater bone turnover as indicated by higher serum alkaline phosphatase activity, serum insulin-like growth factor I and insulin-like growth factor binding protein 3 concentrations, and urinary hydroxyproline. These increases were not affected by soy with either normal or reduced isoflavone content. Similarly, histomorphometry revealed a greater bone formation rate with ovariectomy, and this was not altered by the soy diets. The findings of this study suggest that isoflavones in soy protein are responsible for its bone-sparing effects. Further studies to evaluate the mechanism of action of isoflavones on bone are warranted.
我们之前的研究表明，大豆蛋白饮食可预防卵巢切除引起的骨质流失。本研究的目的是确定大豆蛋白中的异黄酮是否是这种骨骼保护作用的原因。48只95日龄的斯普拉格-道利大鼠被分为4组：假手术组喂食酪蛋白基饮食（SHAM），卵巢切除组喂食酪蛋白基饮食（OVX+CASEIN），卵巢切除组喂食异黄酮含量正常的大豆蛋白（OVX+SOY），以及卵巢切除组喂食异黄酮含量降低的大豆蛋白（OVX+SOY-）。OVX+SOY组的股骨骨密度（每立方厘米骨体积中的克数）显著高于OVX+CASEIN组，而OVX+SOY-组与OVX+CASEIN组相似（平均值±标准差；SHAM，1.522±0.041；OVX+CASEIN，1.449±0.044；OVX+SOY，1.497±0.030；OVX+SOY-，1.452±0.030）。卵巢切除导致骨转换增加，表现为血清碱性磷酸酶活性、血清胰岛素样生长因子I和胰岛素样生长因子结合蛋白3浓度以及尿羟脯氨酸升高。这些增加不受异黄酮含量正常或降低的大豆的影响。同样，组织形态计量学显示卵巢切除后骨形成率更高，而大豆饮食并未改变这一情况。本研究结果表明，大豆蛋白中的异黄酮是其保骨作用的原因。有必要进一步研究以评估异黄酮对骨骼的作用机制。
