Drinking milk stomach upset mainly because of lactose intolerance, milk allergy and other reasons.
1. Lactose intolerance: Because people do not have the habit of drinking milk, so the body lacks lactase, or lactase activity is low, and lactase is an important enzyme in the absorption of milk and other dairy products, the lack of this type of enzyme will lead to milk lactose can not be fully digested, lactose stimulation of the gastrointestinal tract will appear nausea, vomiting, diarrhea and other gastric symptoms of discomfort.
2. Milk allergy: milk is rich in protein, some people are allergic to protein, when a large number of proteins in the gastrointestinal tract is absorbed, the body will produce some of the immune response, such as atopic dermatitis, nausea, diarrhea, abdominal pain and other symptoms.