Globally, most human adults are lactose intolerant. People with lactose intolerance produce insufficient amounts of the enzyme lactase.
Lactase is an enzyme that breaks down lactose (milk sugar) to smaller sugars that can be digested. Lactase is found in the small intestine of mammals. Lactase deficiency occurs in individuals whose bodies produce insufficient amount of the enzyme lactase, and are unable to digest milk very well. These individuals are said to be lactose intolerant.
