Swiatlo N, O'Connor D L, Andrews J, Picciano M F
School of Human Resources and Family Studies, College of Agriculture, University of Illinois, Urbana-Champaign 61801.
J Nutr. 1990 Feb;120(2):172-7. doi: 10.1093/jn/120.2.172.
The present study was designed to determine the relative folate bioavailability from diets containing human, bovine or goat milk and the relative sensitivity of various response criteria used in assessing folate bioavailability. Following a 12-wk depletion period, 16 groups of male rats (n = 5/group) were fed experimental diets with or without 20% milk solids and graded levels of folic acid for 4 wk. Total folates were measured in plasma, erythrocytes, liver and kidney. Bioavailability of dietary folate was determined using slope-ratio statistics. Plasma response was found to be the most sensitive indicator of folate bioavailability based on steepness of slope, goodness of fit (r = 0.96, P less than 0.01) and linearity of response over the entire range of folate intakes. Kidney folate concentration also showed a significant linear relationship to total folate intake (r = 0.69, P less than 0.01). Liver and erythrocyte folate concentrations were not correlated with folate intake (r = 0.33 and r = 0.22, respectively). Using plasma folate as the response criterion, dietary incorporation of human milk significantly enhanced folate bioavailability by 75% (P less than 0.01). With kidney as the response tissue, folate bioavailability from diets containing human and bovine milk was significantly enhanced over milk-free diets. These results show that incorporation of human or bovine milk into diets enhances folate bioavailability and that plasma and kidney folate concentrations are sensitive and specific indicators of folate bioavailability.
本研究旨在确定含人乳、牛乳或羊乳的饮食中叶酸的相对生物利用度，以及评估叶酸生物利用度时使用的各种反应标准的相对敏感性。在12周的耗尽期后，将16组雄性大鼠（每组n = 5）喂食含或不含20%乳固体及不同水平叶酸的实验性饮食，持续4周。测量血浆、红细胞、肝脏和肾脏中的总叶酸。使用斜率比统计法确定饮食中叶酸的生物利用度。基于斜率的陡峭程度、拟合优度（r = 0.96，P < 0.01）以及在整个叶酸摄入量范围内反应的线性度，发现血浆反应是叶酸生物利用度最敏感的指标。肾脏叶酸浓度也与总叶酸摄入量呈显著线性关系（r = 0.69，P < 0.01）。肝脏和红细胞叶酸浓度与叶酸摄入量无相关性（分别为r = 0.33和r = 0.22）。以血浆叶酸作为反应标准，饮食中添加人乳可使叶酸生物利用度显著提高75%（P < 0.01）。以肾脏作为反应组织，含人乳和牛乳的饮食中叶酸的生物利用度比无乳饮食显著提高。这些结果表明，在饮食中添加人乳或牛乳可提高叶酸生物利用度，并且血浆和肾脏叶酸浓度是叶酸生物利用度敏感且特异的指标。
