Lactose Intolerance: Why Many Asians Cannot 'Digest' Milk?

Lactose intolerance is quite common, especially in Asian countries. The reason behind this is gene-culture co-evolution. Lactose intolerance is the inability to digest lactose in milk because they lack the lactase enzyme. A 1981 study found that the percentage of people with lactose intolerance changes from region to region. In East Asia, the numbers are insanely high; 90-100% of East Asians are lactose intolerant. Lactose is the main carbohydrate in milk. It is a vital energy source for young mammals who depend solely on their mothers milk for nutrition. They can readily digest lactose, as they have high amounts of an enzyme called lactase. Lactase breaks down lactose into glucose and galactose, which can then be absorbed by the body and converted into energy. However, lactase production begins to decline as we get older. Lactose intolerance is a condition wherein a person cannot digest lactose in milk because they lack the lactase enzyme. Consuming dairy products cause bloating, gas and diarrhea in such individuals.