Causes
Lactose is the predominant sugar found in milk and other dairy products. The cells in the inner lining of the small intestine produce a digestive enzyme called lactase. Lactase is required to break down lactose into its component sugars (glucose and galactose). The products are then absorbed into the blood stream. Lack of this enzyme affects the whole process. It results in accumulation of high concentration of lactose in the small intestine and this further result in driving in of excess fluid (by the process called osmosis) leading to diarrhoea. The unabsorbed lactose moves to the large intestine, where it gets fermented by bacteria. Flatulence and acidic stool are the outcomes.
Infants have high levels of lactase, allowing them to digest milk. Levels decline with age. Populations of Asian, South American, and African descent are more likely to suffer lactose intolerance. Children usually do not show signs of lactose intolerance until they are at least 3 years old. However premature babies sometimes have lactose intolerance.
Specific causes for intolerance include:
- Bowel surgery
- Infections in the small intestine from viruses or bacteria (cells are damaged)
- Intestinal diseases such as celiac sprue
