While lactose intolerance is more prevalent in certain ethnic groups, anyone lacking sufficient lactase in their body can develop symptoms after ingesting dairy products. There are three different levels of lactose intolerance.
Adult who may have tolerated dairy well during their youth, but for whom lactase production diminishes significantly upon reaching adulthood.
Your small intestine is affected by a surgery, illness or injury and reduces lactase production. This may be due to Crohn’s disease, celiac disease, or infection. Treatment may help lactase production return to normal over time, depending on the original cause.
Babies can be born with a lactase deficiency based on inherited genes from both parents or premature birth. Children born of African, Asian, Hispanic and Native American descent are more prone, but it is still a rare issue for young children. Most people develop lactose intolerance in adulthood.