(HealthDay News) -- Lactose intolerance occurs when the body can't digest lactose, a sugar found in dairy products.

The U.S National Library of Medicine mentions these common reasons for lactose intolerance:

  • The small intestine doesn't produce enough of the enzyme lactase.
  • Premature birth.
  • Bowel surgery.
  • A bacterial or viral infection in the small intestine.
  • An intestinal disease, such as celiac sprue.