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Problems Digesting Dairy Products

Does your stomach churn after you drink milk? Do you have diarrhea soon afterward? If so, you may be lactose intolerant.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) estimates that 30 to 50 million Americans are lactose intolerant.

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Being lactose intolerant means you can't digest lactose-the natural sugar found in milk and other dairy products. People who cannot digest lactose have a shortage, or deficiency, of an enzyme called lactase, which is produced in the small intestine. Lactase breaks down milk sugar into two simpler forms of sugar, which are then absorbed into the bloodstream.

Intolerance is Not Allergy

Lactose intolerance is not the same as a milk allergy, says Kavita Dada, Pharm.D., a senior health promotion officer in the Food and Drug Administration's (FDA's) Division of Drug Information. "For most people with lactase deficiency, it's a discomfort." People who have trouble digesting lactose can learn which dairy products and other foods they can eat without discomfort and which ones they should avoid.

But a food allergy-an abnormal response to a food triggered by the immune system-can be life-threatening. People with food allergies must avoid certain foods altogether. People with food intolerances can often eat small amounts of the offending foods without having symptoms.

Symptoms

When there is not enough lactase to digest the lactose in the foods a person eats or drinks, the person may have

  • gas
  • stomach cramps
  • bloating
  • nausea
  • diarrhea

These symptoms typically occur within 30 minutes to two hours after consuming food containing lactose. Some illnesses can cause these same problems, but a health care professional can do tests to see if the problems are caused by lactose intolerance or by another condition.

Who Becomes Lactose Intolerant?

Lactose intolerance is more common in some ethnic groups than others. NIDDK estimates that up to 75% of all adult African Americans and Native Americans and 90% of Asian Americans are lactose intolerant.

As people age, their bodies produce fewer lactase enzymes, so most people don't have symptoms until they are adults.

Most people inherit the condition from their parents. Lactose intolerance is not very common in children under two years of age, unless the child has a lactase deficiency because of an injury to the small intestine. If you think your infant or child may be lactose intolerant, talk to your child's pediatrician.

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