Wien E M, Schwartz R
J Nutr. 1983 Feb;113(2):388-93. doi: 10.1093/jn/113.2.388.
An in vitro method for measuring dietary mineral exchangeability (miscibility with an extrinsic isotopic tracer) was tested by comparison with in vivo measurements in rats. Collards, spinach and soybeans, intrinsically labeled with 45Ca, were fed to rats together with extrinsically added 47Ca. Absorption of both tracers was determined by measuring their concentrations in the femur 2 days after consumption of the labeled test meals. The same intrinsically and extrinsically labeled foods were digested in vitro for estimation of Ca exchangeability and solubility after peptic-pancreatic digestion. Corresponding in vivo and in vitro estimates of exchangeability agreed closely for the three foods tested. Solubility after in vitro peptic-pancreatic digestion (potential bioavailability) showed discrepancies. In vitro values were somewhat higher for collards than in vivo fractional absorption. The reverse was true for Ca in soybeans and spinach. Thus, the in vitro procedure appears adequate for measuring intrinsic dietary Ca exchangeability but requires modification if it is to be a reliable substitute for in vivo measurements of Ca bioavailability.
通过与大鼠体内测量结果进行比较，测试了一种测量膳食矿物质交换性（与外源性同位素示踪剂的混溶性）的体外方法。将用45Ca进行内源性标记的羽衣甘蓝、菠菜和大豆与外源性添加的47Ca一起喂给大鼠。在食用标记测试餐两天后，通过测量股骨中两种示踪剂的浓度来确定它们的吸收情况。将相同的内源性和外源性标记食物进行体外消化，以评估在胃蛋白酶 - 胰酶消化后的钙交换性和溶解性。对于所测试的三种食物，相应的体内和体外交换性估计值非常接近。体外胃蛋白酶 - 胰酶消化后的溶解度（潜在生物利用度）存在差异。羽衣甘蓝的体外值略高于体内分数吸收率。大豆和菠菜中的钙则相反。因此，体外方法似乎足以测量膳食中钙的内源性交换性，但如果要可靠替代体内钙生物利用度测量，则需要改进。
