Nutting David F, Kumar N Suresh, Siddiqi Shadab A, Mansbach Charles M
Department of Medicine, Division of Gastroenterology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
Curr Opin Gastroenterol. 2002 Mar;18(2):168-75. doi: 10.1097/00001574-200203000-00003.
Many advances in the study of nutrient absorption have been made with the use of molecular and genetic techniques; however, standard in vivo studies have provided interesting and important new information. Omega-3 long-chain fatty acids have unexpected effects on lipoprotein formation and secretion in neonatal intestinal cells; this needs to be considered in the modification of infant formulas. Rexinoids affect intestinal cholesterol homeostasis via two receptors: retinoic acid receptor/liver X receptor (cholesterol efflux to lumen) and retinoic acid receptor/farnesoid X receptor (cholesterol catabolism). Absorption of the antioxidant plant polyphenol quercetin involves interaction with the glucose transporter and deglycolsylation and conjugation reactions. Cells of the polarized human colon cancer cell line, CaCo-2, take up phenylalanine by two mechanisms: passive uptake across the basolateral membrane, and temperature-dependent transcellular movement from apical to basolateral media. Absorption of vitamins A and E is markedly enhanced in normal and damaged intestine by the administration of restructured triacylglycerols derived from fish oil and medium-chain fatty acids. Surprisingly, dietary protein and phosphorus apparently have no significant effect on the efficiency of calcium absorption in adult women. Finally, many studies examined a variety of genes that regulate iron absorption and homeostasis.
利用分子和基因技术在营养吸收研究方面取得了许多进展；然而，标准的体内研究也提供了有趣且重要的新信息。ω-3长链脂肪酸对新生儿肠道细胞中脂蛋白的形成和分泌有意外影响；在婴儿配方奶粉的改良中需要考虑这一点。视黄酸类化合物通过两种受体影响肠道胆固醇稳态：维甲酸受体/肝脏X受体（胆固醇向肠腔的流出）和维甲酸受体/法尼醇X受体（胆固醇分解代谢）。抗氧化剂植物多酚槲皮素的吸收涉及与葡萄糖转运体的相互作用以及去糖基化和共轭反应。极化的人结肠癌细胞系CaCo-2的细胞通过两种机制摄取苯丙氨酸：通过基底外侧膜的被动摄取，以及从顶端到基底外侧介质的温度依赖性跨细胞转运。通过给予源自鱼油和中链脂肪酸的重组三酰甘油，正常和受损肠道中维生素A和E的吸收显著增强。令人惊讶的是，膳食蛋白质和磷对成年女性钙吸收效率显然没有显著影响。最后，许多研究考察了多种调节铁吸收和稳态的基因。
