lactose intolerance is the inability to digest the lactose sugar in milk. milk containing the sugar lactose is a main source of nutrition for infants and young children. with normal lactose tolerance all of the lactose is digested (broken down into two smaller sugars) and absorbed in the small intestine so that none reaches the colon. on the other hand in individuals with lactose intolerance who lack the intestinal enzyme that breaks down the lactose the ingested lactose is neither digested nor absorbed in the small intestine and reaches the colon where it is used by the bacteria in the colon. the bacteria produce chemicals that cause diarrhea and also produce gas. some of the chemicals produced by bacteria include lactic acid and other acids that turn the stool acidic. individuals with intolerance to lactose cannot drink regular cow's milk without developing diarrhea gas and often abdominal pain. they instead must drink substitutes like rice or soy milk or treat cow's milk with an enzyme that digests the lactose (lactaid) so that the smaller sugars can be absorbed in the small intestine.
what is lactose intolerance?