Drinking plain milk causes bloating mainly because many Asians are lactose intolerant and develop bloating, which occurs more and more as they age. If this leads to this condition, patients can eat slowly in small amounts and drink plain milk mixed with other starchy foods to reduce the appearance of flatulence. Patients with lactase deficiency are mainly due to the fact that dairy products cannot be completely absorbed and digested in the gastrointestinal tract, but remain in the intestinal lumen, resulting in increased osmotic pressure of intestinal contents, increased volume, and faster intestinal emptying, so that lactose is quickly discharged to the large intestine, and water is absorbed in the large intestine and fermented by the action of bacteria to produce gas, and the symptoms are not obvious in mild cases, but those with heavy symptoms will have obvious abdominal distension, flatulence, intestinal tinnitus, abdominal pain, and even many People will have diarrhea, you can also drink sour milk, to avoid drinking pure milk bloating situation.