Lactose intolerance is a type of food intolerance that affects between 30 and 50 million Americans, the University of Maryland Medical Center reports. People with lactose intolerance have difficulty digesting a sugar called lactose, which is found in milk and dairy products. If your doctor has diagnosed you with this condition, talk with her about the causes and symptoms of lactose intolerance.
Genetic Inheritance
In rare cases, infants may be born with a genetic condition called congenital lactose intolerance, which is characterized by the absence of lactase -- the enzyme responsible for breaking down lactose, MayoClinic.com reports. Infants with this genetic form of lactose intolerance can't properly digest breast milk and experience chronic diarrhea from birth. Lactose-free types of formula are available for babies with this genetically inherited type of lactose intolerance.
Intestinal Illness or Injury
If you have a digestive illness or sustained an injury to your intestines, you may develop a temporary form of lactose intolerance called secondary lactose intolerance. Intestinal damage or infection may prevent your digestive tract from producing sufficient levels of lactase. Common intestinal diseases that may cause lactose intolerance include gastroenteritis -- also called the stomach flu -- celiac disease and Crohn's disease. In most cases, lactose intolerance symptoms subside once the intestinal illness or injury resolves.
Normal Aging
As you age, the amount of lactase your body produces may gradually decline. Consequently, you may develop lactose intolerance symptoms during early-, mid- or late-adulthood. This type of lactase deficiency -- also called primary lactose intolerance -- is not reversible and typically results in chronic lactose intolerance symptoms. Consult your doctor if you develop symptoms of lactase deficiency to ensure you receive appropriate guidance and treatment.
