Overview Overview dietary carbohydrates include polysaccharides, disaccharides, and monosaccharides intestinal epithelial cells absorb only monosaccharides glucose, galactose, and fructose Digestion of dietary polysaccharides salivary secretions salivary α-amylase initiates digestion of polysaccharides in mouth digests interior α-1,4 glycosidic linkages, yielding 3 disaccharides α-limit dextrins, maltose, and maltotriose salivary α-amylase plays a minimal role in digestion of carbohydrates low pH of gastric contents quickly inactivates salivary α-amylase pancreatic secretions pancreatic juices are secreted into lumen of duodenum of small intestine pancreatic α-amylase initiates digestion of polysaccharides in the small intestines digests interior α-1,4 glycosidic linkages, yielding 3 disaccharides α-limit dextrins, maltose, and maltotriose intestinal mucosa intestinal brush border enzymes initiate digestion of disaccharides to monosaccharides α-dextrinase catalyzes α-limit dextrins → glucose maltase catalyzes maltose → glucose sucrase catalyzes maltotriose → glucose intestinal epithelial cells absorb glucose, a monosaccharide Digestion of dietary disaccharides dietary disaccharides include trehalose, lactose, and sucrose dietary disaccharides do not require α-amylase digestion intestinal brush border enzymes initiate digestion of disaccharides to monosaccharides trehalase catalyzes trehalose → glucose + glucose lactase catalyzes lactose → glucose + galactose sucrase catalyzes sucrose → glucose + fructose intestinal epithelial cells absorb glucose, galactose, and fructose, all monosaccharides