ABSTRACT
The primary site of macronutrient absorption is the small intestine. Given the diversity of the human diet, the ability for a single layer of specialized epithelial cells to impede the passage of ingested toxins and pathogens, while digesting and subsequently absorbing the ingested nutrients required for life is nothing short of monumental. Absorption of dietary nutrients across the epithelium of the gastrointestinal (GI) tract relies on the coordinated activities of specialized digestive enzymes, the products of which are then transported into the specialized absorptive cells lining the intestinal tract via transport proteins. The digestion of macronutrients into their basic units-monosaccharides, amino acids and peptides, and fatty acids, cholesteryl esters, and phospholipids-permits the absorptive enterocytes of the small
2.1 Introduction .................................................................................................... 15 2.2 Carbohydrate Digestion and Absorption ........................................................ 16
2.2.1 Dietary Carbohydrate ......................................................................... 16 2.2.2 Dietary Carbohydrate Digestion ......................................................... 16 2.2.3 Intestinal Monosaccharide Absorption ............................................... 17 2.2.4 Regulation of Monosaccharide Transport .......................................... 18 2.2.5 Dietary Fiber ....................................................................................... 19
2.3 Protein Digestion and Absorption .................................................................. 19 2.3.1 Dietary Protein ................................................................................... 19 2.3.2 Dietary Protein Digestion ...................................................................20 2.3.3 Intestinal Peptide Absorption .............................................................20 2.3.4 Intestinal Amino Acid Absorption ..................................................... 21 2.3.5 Regulation of Peptide/Amino Acid Transport ....................................22
