Lactose intolerance causes gas, bloating, diarrhea, and abdominal cramping in 30 million to 50 million Americans of all ages, according to the University of Maryland Medical Center. Risk factors include aging, intestinal injury or surgery, hereditary, intestinal disease, premature birth and congenital defects. Although some infants and small children suffer from lactose intolerance, most individuals acquire the condition over time or after an injury or surgery.
Lactose
Lactose, also called milk sugar, occurs in varying quantities in milk, cheese, yogurt and other dairy products. It also occurs in any processed food that contains milk or other dairy products, including most breads and baked goods; breaded foods; creamed foods; and products containing cheese such as pizza, lasagna, and macaroni and cheese. The degree to which an individual may react to eating a particular food may depend, at least in part, to the amount of lactose in the food, the size of the serving and whether or not the food is eaten alone or as part of a balanced meal.
Lactose Intolerance
An enzyme called lactase helps the body digest lactose, the primary sugar in milk. If your body produces enough of the enzyme, lactose will digest in your small intestines without causing unpleasant digestive symptoms. Without sufficient amounts of lactase, however, the lactose-containing food passes into the large intestine where bacteria break it down, producing lactic acid. Lactose intolerant individuals experience mild to severe diarrhea, gas, abdominal cramping and bloating within 30 minutes to two hours of consuming products containing lactose, according to MayoClinic.com.
Infants and Children
Most infants produce enough of the lactase enzyme to digest milk, their main source of nutrition. As they get older and add solid foods to their diets, however, lactase production diminishes. In fact, full-term babies seldom display symptoms of lactose intolerance until they reach the age of 3 or older, although African American children may develop the condition as early as 2 years old, according to MedlinePlus. Rarely, infants with a hereditary condition are born without the ability to produce lactase and must be fed with lactose-free formula.
Adults
Lactose intolerance can develop slowly and the symptoms may be confused with other digestive conditions, so pinpointing the age of onset can be difficult. An estimated 30 million American adults have symptoms of lactose intolerance by the time they reach age 20 and the incidence increases with advancing age, according to MedlinePlus. Some ethnic groups are more prone to develop lactose intolerance than others. People of northern European heritage have the lowest incidence of lactose intolerance, according to the University of Maryland Medical Center. Approximately 75 percent of African-Americans and Native Americans have lactose intolerance and 90 percent of Asian-Americans have the condition.
Intestinal Injury or Illness
Certain intestinal diseases, injuries and illnesses can reduce the production of the lactase enzyme, causing lactose intolerance. Patients of any age with celiac disease, inflammatory bowel disease and gastroenteritis may develop lactose intolerance that may reverse when the underlying condition has been treated. Gastric bypass, a type of weight loss surgery procedure performed only on adults, can reduce lactase production in the small intestine and cause the patient to become lactose intolerant.
