Carbohydrate digestion - wikipedia Carbohydrate digestion For a fuller description of human digestion, see Gastrointestinal physiology. This article has multiple issues. Please help improve it or discuss these issues on the talk page. ( Learn how and when to remove these template messages ) This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( March 2016 ) This article is an orphan, as no other articles link to it. Please introduce links to this page from related articles ; try the Find link tool for suggestions. ( September 2014 ) All carbohydrates absorbed in the small intestine must be hydrolyzed to monosaccharides prior to absorption. Hydrolysis precedes transport of monosaccharides in hamster intestine. From sucrose, glucose is taken up much faster than fructose. Monosaccharide transport saturates with D - glucose at 30 mM. Digestion of starch begins with the action of salivary alpha - amylase / ptyalin, although its activity is slight in comparison with that of pancreatic amylase in the small intestine. Amylase hydrolyzes starch to alpha - dextrin, which are then digested by gluco - amylase ( alpha - dextrinases ) to maltose and maltotriose. The products of digestion of alpha - amylase and alpha - dextrinase, along with dietary disaccharides are hydrolyzed to their corresponding monosaccharides by enzymes ( maltase, isomaltase, sucrase and lactase ) present in the brush border of the small intestine. In the typical Western diet, digestion and absorption of carbohydrates is fast and takes place usually in the upper small intestine. However, when the diet contains carbohydrates not easily digestible, digestion and absorption take place mainly in the ileal portion of the intestine. Digestion of food continues while simplest elements are absorbed. The absorption of most digested food occurs in the small intestine through the brush border of the epithelium covering the villi ( small hair - like structure ). It is not a simple diffusion of substances, but is active and requires energy use by the epithelial cells. During the phase of carbohydrate absorption, fructose is transported into the intestinal cell 's cytosol, glucose and galactose competes with other ( Na ) transporter required for operation. From the cytosol, monosaccharides pass into the capillaries by simple or facilitated diffusion. Carbohydrates not digested in the small intestine, including resistant starch foods such as potato, bean, oat, wheat flour, and several monosaccharide oligosaccharides and starch, are digested in a variable when they reach the large intestine. The bacterial flora metabolize these compounds anaerobically in the absence of oxygen. This produces gases ( hydrogen, carbon dioxide and methane ) and short - chain fatty acids ( acetate, propionate, butyrate ). The gases are absorbed and excreted by breathing or through the anus ( flatulence ). Fatty acids are rapidly metabolized. Butyrate is used mainly by cells in the colon and acetate is absorbed into the blood and taken up by the liver, muscle and other tissue. Propionate is an important precursor of glucose in some animals, but not humans. References Jump up ^ Alvarado, F ; Lherminier, M ; Phan, HH ( October 1984 ). `` Hamster intestinal disaccharide absorption : extracellular hydrolysis precedes transport of the monosaccharide products ''. The Journal of Physiology. 355 : 493 -- 507. doi : 10.1113 / jphysiol. 1984. sp015434. PMC 1193506. PMID 6492000. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Carbohydrate_digestion&oldid=785909523 '' Categories : Nutrition Carbohydrates Hidden categories : Articles needing additional references from March 2016 All articles needing additional references Orphaned articles from September 2014 All orphaned articles Articles with multiple maintenance issues Talk About Wikipedia Українська Edit links This page was last edited on 16 June 2017, at 03 : 49. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: where does the complete digestion of carbohydrates occur
Answer: the upper small intestine