Abad A R, Gregory J F
J Nutr. 1987 May;117(5):866-73. doi: 10.1093/jn/117.5.866.
Variations of a recently proposed rat bioassay were examined and applied to the measurement of biologically available folate. The concentration of hepatic folate was found to be inconsistent as a response indicator, although fasting levels of plasma folate accurately reflected available dietary folate. Studies involving the control of coprophagy suggested that fecal folate significantly contributes to the folate status of the rat. Bioassays employing multiple dietary levels of dried orange juice solids or blanched cabbage without control of coprophagy were conducted to determined available folate by slope-ratio methods. The apparent bioavailability of endogenous folate in the dried orange juice and cabbage was 146 and 68%, respectively, relative to folic acid. The presence of dried orange juice solids or cabbage did not inhibit the utilization of folate pentaglutamate added to the diets. These results illustrate the usefulness and several limitations of the rat bioassay for evaluating the bioavailability of folate. However, the appropriateness of the rat as a model of human folate digestion and absorption requires further investigation.
对最近提出的大鼠生物测定法的变体进行了研究，并将其应用于生物可利用叶酸的测量。发现肝脏叶酸浓度作为反应指标不一致，尽管空腹血浆叶酸水平准确反映了可利用的膳食叶酸。涉及控制食粪症的研究表明，粪便叶酸对大鼠的叶酸状态有显著贡献。进行了采用多种膳食水平的干橙汁固体或焯过的卷心菜且未控制食粪症的生物测定，以通过斜率比法测定可利用叶酸。相对于叶酸，干橙汁和卷心菜中内源性叶酸的表观生物利用率分别为146%和68%。干橙汁固体或卷心菜的存在并不抑制添加到日粮中的叶酸五谷氨酸的利用。这些结果说明了大鼠生物测定法在评估叶酸生物利用率方面的有用性和若干局限性。然而，大鼠作为人类叶酸消化和吸收模型的适用性需要进一步研究。
