What Is Lactose Intolerance?

I am often asked the question "What is lactose intolerance?", so I figured I would start out with explaining the basics of lactose intolerance.

Lactose intolerance is the body's inability to digest lactose, a natural sugar found in milk and other dairy products, and lactose intolerance occurs when the small intestine does not make enough of the enzyme called lactase.

The body needs lactase to break down lactose, and without it digesting lactose can cause very uncomfortable symptoms. The symptoms of lactose intolerance include gas, nausea, stomach aches, diarrhea and bloating.

The symptoms and the severity of symptoms vary from person to person, and while some people with lactose intolerance are forced to refrain from consuming any dairy products, others can drink small amounts of milks, certain types of milks and consume small amounts of dairy products without symptoms. 

The onset of lactose intolerance varies as well, and while some show symptoms from infancy, it is more common for a later onset. Lactose intolerance is most common in people with Asian, African, Native American, or Mediterranean ancestry, and it is rare among those with a northern and western European genetic heritage. Lactose intolerance is especially prevalent in Asians and Native Americans, and up to 80 percent of African Americans and Hispanic Americans also have symptoms of lactose intolerance. 

The reason for the connection between lactose intolerance and genetic makeup is quite simple, as those who are more likely to have lactose intolerance had ancestors, who did not eat dairy foods. Their bodies were therefore not not prepared to digest dairy, and they passed these genes on from generation to generation.

Other factors than genetics may play a role in lactose intolerance, as people with bowel diseases, people who have had bowel surgery and those whose intestines have been affected by virus or disease are likely to become lactose intolerant as well.

The prevalence of lactose intolerance around the world.

According to the U.S. National Library of Medicine about 30 million American adults have some amount of lactose intolerance by age 20.

Sources: Web Md, National Digestive Diseases Information Clearinghouse (NDDIC)

and U.S. National Library of Medicine.

Map from Wikipedia