Lactose intolerance in the Chinese population

An overwhelming proportion of the Chinese population is lactose intolerant. The prevalence of lactose intolerance in Asia and also in Africa is estimated to be between 80-100%, whereas the prevalence of the condition in Northern Europe is between 1-18%, with specific national percentages of 15-20% for Germany and 25% for the Mediterranean region.

Lactose intolerance is the inability to process or digest lactose, which is the result of a defect in the digestive enzyme lactase. Lactase is located in the mucous membrane of the small intestine and splits lactose into glucose and galactose, which can then be absorbed directly.

Some people are born completely without lactase, but more commonly, the lactase slowly loses its ability to function after a baby is weaned. This is why the prevalence of the condition in the Chinese population is age-dependent. According to the theory of evolution, a higher consumption of lactose in some population groups (such as in Northern Europe) has led to an active mutation in the lactase gene which leads to a lifelong functioning of lactase.

Lactose intolerant Asians display the same symptoms as lactose intolerant Europeans. The undivided lactose passes undigested into the large intestine, where bacteria convert it to lactic acid, carbon dioxide, methane, hydrogen, acetic acid, and water. These gases are the cause of symptoms such as bloating, cramping, stomach pain, colic, diarrhea, and nausea.

Osteoporosis, caused by insufficient calcium intake, is a significant health problem in Asian countries. Milk and dairy products are the most effective suppliers of calcium; thus a higher milk intake is being recommended even in these regions. In the last 20 years, consumption of milk and dairy products has increased by about 660% percent in urban areas. Studies about dietary supplementation through powdered milk have shown that low levels of lactose can be tolerated. In most lactose intolerant patients, whether Chinese or European, lactase is present and active at a residual level.

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