Lactose intolerance is a condition caused by a deficiency in the amount of lactase, an enzyme produced by cells in the small intestine. Without sufficient lactase, you cannot break down the lactose sugar in milk. This causes gastrointestinal upset including stomach pain, gas and bloating. The symptoms usually begin shortly after eating dairy foods. Lactose intolerance is common, affecting some 70 percent of the world's population. Some ethnic groups are at a higher risk of developing the condition than others.
Prevalence
Lactose intolerance is rare among those of Northern European ancestry, a region where historically dairy products have been a part of the diet throughout adulthood. Only 2 percent of individuals of Northern European ancestry develop lactose intolerance. Among Hispanic people the prevalence of lactose intolerance is 50 to 80 percent. 60 to 80 percent of black and Ashkenazi Jewish adults and almost 100 percent of Asian and American Indian adults are lactose intolerant.
Age of Onset
In addition to the prevalence of the condition, the age at which it appears varies among different ethnic populations. Infants need the lactase enzyme to digest lactose sugar in their mother's milk. Lactase production slows with aging. Caucasian children rarely develop lactose intolerance before the age of 4 or 5. In contrast, among Hispanic, Asian, and black populations, approximately 20 percent of children under age 5 have signs of lactose intolerance.
Implications
The American Academy of Pediatrics points out the importance of these statistics on lactose intolerance and ethnicity for diagnosis. Since lactose intolerance is very rare among young Caucasian children, physicians need to look for other explanations of dairy sensitivity, such as milk allergy or other gastrointestinal conditions. Among populations at risk of lactose intolerance, it is useful to consider early measures to bolster calcium and prevent malabsorption.
Other RIsk Factors
Lactose intolerance is more common in premature infants born at less than 34 weeks' gestation. This is known as developmental or neonatal lactose intolerance and it is caused by an immature gastrointestinal tract. Gastrointestinal illness or injury to the intestine can result in secondary lactose intolerance. When the underlying condition is treated, lactose absorption returns to normal.
