What Is It? 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. 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). Lactose
intolerance usually is genetic (inherited). In many people of
African or Asian descent, the body begins making less lactase
around age 5. As many as 90 percent of Asian-Americans, 80
percent of American Indians, 65 percent of African-Americans and
50 percent of Hispanics have some