Arjmandi B H, Khalil D A, Hollis B W
Department of Nutritional Sciences, 416 Human Environmental Sciences, Oklahoma State University, Stillwater 74078-614, USA.
Calcif Tissue Int. 2002 Jun;70(6):483-7. doi: 10.1007/s00223-001-1100-4. Epub 2002 Apr 30.
Recent reports indicate that soy protein and its isoflavones exert beneficial effects on bone in ovarian hormone deficiency. These positive effects, in part, may be due to improved intestinal calcium (Ca) absorption. We examined the role of soy protein or its isoflavones on intestinal Ca transport using ovariectomized rats. Rats were fed either a casein- or a soy protein-based diet with normal or depleted isoflavone levels. After 35 days of treatment, rats were exsanguinated and isolated cells from all intestinal segments were used to measure in vitro Ca transport. Ovariectomy significantly decreased the rates of Ca transport in duodenal and colonic cells, which were prevented by soy protein with normal isoflavone content. This enhanced Ca transport by isoflavones present in soy protein appeared to be independent of circulating insulin-like growth factor-I, 25(OH)vitamin D, or l,25(OH)2vitamin D as these variables were unaffected by dietary treatments. The findings of this study imply that soy isoflavones may promote Ca absorption in a manner analogous to that of estrogen but without exerting uterotrophic effect. Further studies are needed to explore the mechanism(s) by which soy protein or its isoflavones promote intestinal Ca absorption in ovarian hormone deficiency.
最近的报告表明，大豆蛋白及其异黄酮对卵巢激素缺乏状态下的骨骼具有有益作用。这些积极作用部分可能归因于肠道钙（Ca）吸收的改善。我们使用去卵巢大鼠研究了大豆蛋白或其异黄酮对肠道钙转运的作用。给大鼠喂食酪蛋白或大豆蛋白为基础的饮食，其异黄酮水平正常或缺乏。治疗35天后，处死大鼠，取所有肠段的分离细胞用于体外钙转运测定。去卵巢显著降低十二指肠和结肠细胞的钙转运速率，而含正常异黄酮含量的大豆蛋白可预防这种降低。大豆蛋白中存在的异黄酮增强的钙转运似乎独立于循环中的胰岛素样生长因子-I、25（OH）维生素D或1,25（OH）2维生素D，因为这些变量不受饮食处理的影响。本研究结果表明，大豆异黄酮可能以类似于雌激素的方式促进钙吸收，但不产生子宫营养作用。需要进一步研究以探索大豆蛋白或其异黄酮在卵巢激素缺乏状态下促进肠道钙吸收的机制。
