Lactose intolerance is the inability to digest significant amounts of lactose, the major sugar found in milk and milk products.
Lactose intolerance is caused in part by a shortage of lactase, an enzyme produced by the cells that line the small intestine. Lactase breaks lactose down into the simple forms of sugar, glucose, and galactose, so they can be absorbed and used by the body.
Infants have the highest levels of lactase, which helps them digest their mother's milk. In about 75% of the world's population, a genetic trait causes lactase levels to start irreversibly decreasing after weaning. By adulthood, most lactase activity is lost. Although the decline in lactase activity affects the majority of the population, not everyone has symptoms of lactose intolerance after consuming normal amounts of lactose.
Whether or not people develop symptoms appears to be linked to the ability of a certain type of beneficial bacteria, called lactic acid bacteria, to break down lactose.
Lactic acid bacteria in the intestines breaks lactose down into short-chain fatty acids and other substances that can be absorbed by the colon. They are available in supplement form as capsules, tablets, or powders in the refrigerated section of health food stores, grocery stores, drug stores and online.
