Lactose intolerance is a common cause of abdominal cramping, bloating and diarrhea. This condition occurs when the body does not have enough of the intestinal enzyme lactase. The job of lactase is to break down lactose, the main sugar in milk. Once lactose is broken down into simpler forms of sugar, these simple sugars can be absorbed into the bloodstream.
In normal digestion, lactose is digested in the small intestine without the release of gas bubbles. When lactose can't be digested well, it passes into the colon. Bacteria in the colon break down some of the lactose, producing hydrogen gas. The remaining lactose also draws water into the colon. The extra gas and water result in symptoms, such as cramping, diarrhea, bloating and flatulence (gas).
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