Why Do Asians Often Experience Stomach Pain After Drinking Milk?

According to the US National Institutes of Health and the World Gastroenterology Organisation, approximately 68-70 per cent, or five billion adults worldwide, experience lactose intolerance. Lactose intolerance is a digestive disorder that occurs when the body is unable to digest lactose, the natural sugar found in milk and various dairy products.

This condition can cause symptoms such as bloating, diarrhoea, abdominal pain, nausea, and discomfort after consuming milk or dairy products. Interestingly, in Asian countries such as China, Japan, Korea, and Vietnam, the rate of lactose intolerance reaches 9-95 per cent. Why does this happen?

According to an ecological genetics expert from IPB University, Professor Ronny Rachman Noor, lactose intolerance is more common among non-Caucasian races, including Asian populations. This is because they typically do not experience the mutation in the ‘lactase persistence’ gene, which allows the production of the lactase enzyme to continue into adulthood.

“The mutation of the lactase persistence gene, which occurred about 7,500 years ago in Northern Europe, allows adults there to digest lactose well, so Caucasian races tend to have low intolerance rates, at only 5-15 per cent,” Professor Ronny stated in a written statement, quoted last week.

In Asia, Africa, and most of the Americas, the culture of consuming fresh milk developed more slowly and did not become a primary part of traditional diets. As a result, the lactase persistence mutation was not strongly selected and remains rare in these populations.

What about Indonesia? According to Professor Ronny, the percentage of lactose intolerance in Southeast Asia is also very high, reaching 85-98 per cent. Lactose intolerance in children aged 3-5 years in Indonesia reaches 21.3 per cent and increases with age. For children aged 6-11 years, the rate is 57.8 per cent, with further increases observed in adolescents and the elderly.