I get bloating, abdominal pain, and diarrhea after drinking milk. How should I drink milk?

Popular Science Times reporter Chen Jie

May 12-18 is the 10th National Nutrition Week, with the theme of "Milk and beans add nutrition, less oil is healthier." Seeing this theme, people with lactose intolerance may wonder: I feel uncomfortable after drinking milk, can I still drink it?

Milk and dairy products are good for human health, but many people are deterred from drinking dairy products because they experience adverse reactions such as bloating, abdominal pain, and diarrhea.

"This may be what we often call lactose intolerance." Xu Zhipeng, deputy chief physician of the Department of Gastroenterology at the Second Affiliated Hospital of Zhejiang University School of Medicine, told reporters that lactose intolerance is due to the body's lack of lactase and inability to digest lactose. Symptoms such as abdominal distension, diarrhea, and spasmodic abdominal pain appear after eating milk or dairy products.

During this year's National Nutrition Week, an "Expert Consensus on Lactose Intolerance and Scientific Milk Drinking" reminded people that scientific milk drinking can also improve the symptoms of lactose intolerance.

Han Junhua, secretary general of the Chinese Nutrition Society, said that the "Dietary Guidelines for Chinese Residents (2022)" recommends that adults consume 300 ml or more of liquid milk per day, while the average daily milk intake in my country is less than 30 ml. A sample survey of people in eight cities showed that the perception of lactose intolerance is an important factor affecting the insufficient intake of dairy products by Chinese residents.

Lactose is the main carbohydrate found in milk and dairy products. "Lactose intolerant people cannot break down the lactose they eat into monosaccharides for absorption. Undigested lactose enters the colon and is fermented by bacteria to produce short-chain fatty acids, as well as methane, carbon dioxide and other gases." Xu Zhipeng said that the accumulation of gas can cause symptoms such as bloating, and undigested lactose and its fermentation products can increase the osmotic pressure in the intestine, leading to an increase in the amount of water flowing into the intestine, thus causing diarrhea.

In medicine, lactase deficiency can be divided into primary lactase deficiency, secondary lactase deficiency and congenital lactase deficiency. Primary lactase deficiency is caused by the gradual decrease in lactase amount and activity as people age, and is more common in people aged 7-8 years old; secondary lactase deficiency is caused by various diseases that damage the small intestinal mucosa, resulting in reduced lactase secretion and low activity, and most of them are temporary; congenital lactase deficiency is caused by recessive genes on the chromosomes of some people, which leads to lactase deficiency. This type is relatively rare in clinical practice.

"Of course, bloating after drinking milk does not necessarily mean lactose intolerance." Xu Zhipeng emphasized that the human body is allergic to certain sugars or additives, and the gastrointestinal tract is more sensitive to cold things, which may also cause bloating and diarrhea after drinking milk.

"The symptoms appear after drinking milk and are significantly relieved after stopping eating. In this case, lactose intolerance is most likely," said Xu Zhipeng.

Lactose has rich nutritional value, and we cannot exclude lactose intake due to lactose intolerance. "People with lactose intolerance can choose low-lactose or lactose-free dairy products, such as lactose-free milk, yogurt and cheese; they need to control the amount at the beginning, starting with 100 ml and gradually increasing the amount; they can also consume dairy products with other foods and heat the milk to about 40°C to help reduce symptoms; in addition, appropriate supplementation of lactase, probiotics and prebiotics can also alleviate and improve lactose intolerance symptoms." Xu Zhipeng reminded.