What is Lactose Intolerance?
Lactose is a disaccharide (two sugar molecule) made up of glucose and galactose, commonly found in cow, sheep, goat and all mammals’ milk. Normally lactose is broken down by the enzyme lactase (which is produced in the villi that line our small intestine) into its single sugars to enable its absorption and use by the body. However, the production of the lactase enzyme can be impaired by damage to the small intestine, such as the result of a gastrointestinal infection or untreated coeliac disease and is also known to gradually decrease as we age. Once the infection is treated or the inflammation resolved the lining of the intestine can recover and tolerance to lactose can return within a few weeks.
Without adequacy of the lactase enzyme, the lactose sugar is not digested normally in the small intestine and instead it passes through to the large intestine where it is readily fermented by the colonic bacteria. This fermentation can cause such common symptoms as diarrhoea, loose bowel motions, excessive flatulence, abdominal bloating and discomfort.
The degree and severity of symptoms depends on the level of lactase insufficiency. Many people with lactose intolerance have a particular tolerance level, which often allows them to consume some lactose with minimal symptoms such as milk in tea, or larger quantities spread over the day.