Lactose is the sugar found in milk. Lactose intolerance is when the small intestine does not make enough of the enzyme lactase needed to break down the lactose so it can be used for energy. If it is not properly broken down, it becomes food for the bacteria living in the large intestine or colon. That can cause gas, pain, bloating, nausea and diarrhea. To learn more about the symptoms, diagnosis and treatment of lactose intolerance in children, download the GIKids Fact Sheet on Lactose Intolerance.
Read more here: