What is Lactose Intolerance?
Firstly, lactose intolerance is not an allergy and the symptoms are not the result of an immune response.
Lactose intolerance occurs when the lactase enzyme is missing from the small intestine. Lactase is used to break down lactose into simple sugars, glucose and galactose, which are easily digested.
When lactase is missing in the digestive system the lactose passes intact to the colon. The bacteria in the colon metabolise the lactose which results in a fermintation process that produces a lot of gas (hydrogen, carbon dioxide and methane). The unabsorbed sugars and by-products of the fermentation process can also cause an increased flow of water into the bowels with unpleasent consequences.
How Do You Become Lactose Intolerant?
- Depending on your ethnic back ground you may not have the ability to produce lactase or make enough lactase after you have been weaned.
In mammals lactase expression is turned on at birth but then dimineshes once the infant mammals are weaned (i.e., stop getting milk from their mothers). In humans, a mutation evolved 5,000 to 10,000 years ago that allows lactose expression to persist through adulthood. The conditions for this are thought to have developed once early humans started herding dairy animals as the ability to consume milk and milk products as a food source provides a huge evolutionary advantage.
For this reason, lactose intolerance is not prevalent in people whose ancestors come from regions were herding dairy animals was common. For example, only about 5% of Northern Europeans suffer lactose intolerance whereas it can be as high as 90% in some Mediterranean, African or Asian populations.
Arabian, Indian and some specific African populations from traditionally herding cultures have a high tolerance of lactose.
It is also interesting that southern Asian cultures who are genetically lactose intolerant do not suffer the symptoms when they consume large amounts of milk because yogurt plays an important role in their diet. The lactobacilli in live yogurt cultures are able to breakdown the lactose in any other dairy product that is also consumed.
- Acquired Lactose Intolerance.
Illness such as gastroenteritis or chemotherapy treatment can strip the small intestine of the lactase enzyme. However, this condition should improve after the lining of the gut heals.
What to do about Lactose Intolerance?
Because lactose intolerance is not an allergy small amounts of lactose are not necessarily an issue even for people who don’t have lactase persistence. A serve of full cream milk has about 5g of lactose (human milk has nearly double that amount!) but a whey protein isolate has less than half a gram per serve if mixed with water.
Another option that allows you to enjoy dairy products with higher levels of lactose is to take supplemental lactase such as Lacteeze.
For more information about lactose intolerance, especially in regards to infants, see the Better Health Victoria Fact Sheet