<P> Lactase is an enzyme produced by many organisms . It is located in the brush border of the small intestine of humans and other mammals . Lactase is essential to the complete digestion of whole milk; it breaks down lactose, a sugar which gives milk its sweetness . Lacking lactase, a person consuming dairy products may experience the symptoms of lactose intolerance . Lactase can be purchased as a food supplement, and is added to milk to produce "lactose - free" milk products . </P> <P> Lactase (also known as lactase - phlorizin hydrolase, or LPH), a part of the β - galactosidase family of enzymes, is a glycoside hydrolase involved in the hydrolysis of the disaccharide lactose into constituent galactose and glucose monomers . Lactase is present predominantly along the brush border membrane of the differentiated enterocytes lining the villi of the small intestine . In humans, lactase is encoded by the LCT gene . </P> <P> Lactase is an enzyme that some people are unable to produce in their small intestine . Without it they can't break down the natural lactose in milk, leaving them with diarrhea, gas and bloating when drinking regular milk . Lactase is added to Lactose Free Milk to neutralize lactose naturally found in milk, leaving it slightly sweet but digestible by everyone . Without lactase, lactose intolerant people pass the lactose undigested to the colon where bacteria break it down creating carbon dioxide and that leads to bloating and flatulence . </P> <P> Lactase supplements are sometimes used to treat lactose intolerance . </P>

Where is lactase found in the digestive system