Lactose Intolerance

I know that certain digestive diseases and injuries to the small intestine can reduce the amount of enzymes that are produced. In rare cases, children could be born without the ability to produce lactase. For most people, as I have experienced, lactase deficiency is a condition that develops naturally over time. I have this problem for a year already so I need to know a little bit more about it. What is lactose intolerance actually, what is the main process of this disorder?

Lactose intolerance is inability to digest significant amounts of lactose, the predominant sugar of milk. This inability results from a shortage of the enzyme lactase. This enzyme is normally produced by the cells that line the small intestine. Lactase breaks down milk sugar into simpler forms that can then be absorbed into bloodstream. When there is not enough lactase to digest the amount of lactose consumed, results may be very distressing. While not all persons deficient in lactase have symptoms, those who do are considered as lactose intolerant. Common symptoms include nausea, cramps, bloating, gas, and diarrhea. These symptoms usually begin about 30 minutes to 2 hours after eating or drinking foods containing lactose. The severity of symptoms varies depending on the amount of lactose each individual lactose intolerant patient can tolerate. To determine if someone is lactose intolerant, the most common tests used to measure the absorption of lactose in the digestive system are the lactose tolerance test, the hydrogen breath test, and the stool acidity test, performed on an outpatient basis at a hospital, clinic, or doctor's office.