Lactose intolerance means the body cannot easily digest lactose, a type of natural sugar found in
milk and dairy products. This is due to the lack of the enzyme lactase,which the body needs to digest lactose, in the digestive tract. When lactose moves through the large intestine without being properly digested, it can cause
uncomfortable symptoms such as gas, belly pain, and bloating.
Lactose intolerance is common in adults. It occurs more often in
Native Americans and people of Asian, African, and South American descent than
among people of European descent. It is thought that original human populations did not retain the ability to make the enzyme lactase after childhood. Subsequently populations that began herding milk producing mammals, favoured individuals with genetic mutations that meant lactase was produced in adulthood.
Lactose intolerance most commonly
runs in families, and symptoms usually develop during the teen or adult years. Additionally, sometimes the small intestine stops
making lactase after a short-term illness such as the gastric flu or food poisoning or as part of a lifelong disease such as cystic fibrosis.
Although lactose is present in cow, goat and sheep milk, there is a difference. Goat and sheep milk does not contain as much lactose and is coated in vitamin K; this coating means that it is passed through the gut and does not remain there, allowing easy passage through the large intestine, without giving the reaction that cows' milk can give. Goat milk is also higher in calcium and lower in cholesterol than cows' milk.
Some people with lactose intolerance can take small amounts of lactose without showing symptoms (e.g. some lactose is present in some tablet medications, including birth control pills). These people amy be able to eat cow's milk yoghurt, as the process of turning milk into yoghurt uses bacteria that convert lactose to lactic acid, thus greatly reducing the amount of lactose present.
Various sources
