描述
Lactose Intolerance (Hypolactasia, Adult type; Adult Lactase Deficiency; Disaccaride Intolerance III; Lactase Persistence, Included) is caused by a deceased expression of intestinal lactase, an enzyme expressed in newborns. Its activity declines following weaning. Lactase deficiency is present in up to 80 percent of blacks and Latinos, and up to 100 percent of American Indians and Asians. Persons with lactose intolerance are unable to digest significant amounts of lactose. Due to the reduced lactase level, lactose present in dairy products cannot be digested in the small intestine and instead are fermented by intestinal bacteria. Common symptoms include abdominal pain and bloating, excessive flatus, and watery stool following the ingestion of foods containing lactose. Excess lactose may be present in the urine.