Lactose intolerance refers to the inability to digest significant amounts of lactose, which is the main sugar found in milk.
In order to be digested, lactose must first be broken down into two smaller sugars. This is accomplished by the enzyme lactase that is produced by the cells that line your small intestine.
When lactase is absent, lactose passes through the intestine to the colon (large bowel), carrying extra fluid with it. In the colon, bacteria break down lactose into lactic acid and certain gases. Lactic acid is
an irritant and laxative. It can cause symptoms such as bloating, diarrhea, abdominal cramps, and gas or flatus.
Lactase enzyme
- Lactase (LCT), a member 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. In humans, lactase is present predominantly along the brush border membrane of the differentiated enterocytes lining the villi of the small intestine.
- Lactase is essential for digestive hydrolysis of lactose in milk. Deficiency of the enzyme causes lactose intolerance.
- The optimum temperature for lactase is about 48 °C (118.4 °F) for its activity and has an optimum pH of 6.5.
- Lactase breaks lactose down into smaller sugars that can be easily absorbed into the bloodstream.
In lactose intolerance, your body does not produce enough lactase to break down all the lactose in the foods that you eat and the beverages that you drink.