Malabsorption Syndrome Lactose Intolerance

Lactose intolerance is the body ‘s inability to digest a sugar called lactosepredominantly found in milk and other dairy products. This inability is a result of the body ‘s failure to produce enough of the enzyme lactase.

Lactose intolerance is a fairly common disorder. An estimated thirty to fifty million Americans have some degree of lactose intolerance.

The severity of lactose intolerance varies among individuals. Some people can ingest small amounts of milk and cheese without exhibiting symptoms. Others may ingest certain products containing lactose (such as ice cream) without problems while other lactose-containing foods generate extreme discomfort.

What Does Lactase Do?

Lactase is an enzyme produced by the small intestine to break down lactose (a complex sugar). If the body is able to produce enough lactase, the lactose is broken down into simple sugars, glucose and galactose, which are then absorbed into the bloodstream. Various cells in the body then utilize the glucose while the galactose is transported to the liver, where it is converted to glucose.

Who Is Lactose Intolerant?

Lactose intolerance seems to affect certain ethnicities more than others. Approximately 75 percent of African Americans and American Indians are lactose intolerant. The condition is even more prevalent in Asians, who are ninety percent lactose intolerant.

Interesting Note on Lactose Intolerance

Lactose intolerance generally increases in prevalence with age. Infants and newborn babies often produce more than enough lactase to digest the lactose found in breast milk and dairy products. After the age of two, however, the body decreases its production of lactase, and the decline continues with age.

Causes of Lactose Intolerance

Lactose intolerance may be a result of ethnicity or age, or it may be secondary to a disease such as celiac sprue or due to damage to the intestine as a result of injury or surgery. Inflammation of the small intestine as a result of bacteria or viruses may cause temporary lactose intolerance. In some rare cases, babies are unable to produce lactase at all.

Symptoms of Lactose Intolerance

The severity of the symptoms depends on the individual. Symptoms depend on how much lactose is ingested and how much is tolerated by the body. Some of the more common symptoms of lactose intolerance include:

  • bloating
  • gas
  • nausea
  • abdominal cramping/pain
  • diarrhea.

Most symptoms occur soon after the ingestion of lactoseapproximately thirty minutes to two hours after.

Diagnosing Lactose Intolerance

Most people know if they ‘re lactose intolerant. For others who are unsure, various tests can be performed to determine if lactose intolerance is a problem:

  • The lactose tolerance test:

    Fasting is required prior to the test. A liquid containing lactose is then given to the patient. Over the next two hours, periodic blood tests are taken to measure blood glucose level. People who are lactose tolerant will have an increased blood glucose level while people who are intolerant will not see the same rise in their blood glucose level.

  • The hydrogen breath test: The patient is given a liquid containing lactose. Periodic breath tests are then taken to measure the hydrogen level. Normally, hydrogen levels are very low, but if lactose is improperly broken down, the bacteria in the small intestine cause fermentation of the sugar and hydrogen is produced. The hydrogen is absorbed into the blood, transported to the lungs and expelled.
  • The stool acidity test: This test is often the diagnostic of choice for infants and young children because ingesting a large amount of food containing lactose can pose a serious health risk to children who are lactose intolerant. In this test, the amount of acid in the patient ‘s stool is measured. People with lactose intolerance are unable to completely digest the lactose. The bacteria will ferment the sugar, resulting in the creation of various acids in the stool.

Treating Lactose Intolerance

Lactose intolerance is a fairly easy condition to treat. Once people are aware of their lactose intolerance, they can figure out the limits of their tolerance and eventually discover how much lactose they can ingest without experiencing symptoms.

Cow ‘s milk contains the most lactose, so people with lactose intolerance can try other dairy products with less lactose, such as yogurt, cheese or even goat ‘s milk.

Those who react to tiny amounts of lactose or have very severe symptoms should avoid foods containing lactose altogether. Supplemental lactase is a possible alternative. Supplemental lactase is easy to obtain and can make the digestion of dairy products much easier.

The Calcium Problem

Dairy products are the primary source of calcium for most people. Calcium is very important, especially in young children, for the proper development of strong bones and, in the elderly, for preventing osteoporosis.

People who are lactose intolerant tend to avoid dairy products, which may eventually result in a calcium deficiency. Fortunately, many dairy-free calcium sources are available, including:

  • vegetables such as broccoli or Chinese cabbage
  • fish with soft bones such as sardines or salmon
  • oysters and other types of seafood
  • tofu processed with calcium.

In some cases, calcium supplements may be required to meet the recommended daily allowance of calcium.

The RDA of Calcium

Most people need about 1000 mg of calcium each day. Pregnant women, the elderly, and women after menopause generally need at least 1200 mg per day.


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Armstrong, C. (updated 2002). Recommended daily allowances (RDA). North Memorial Medical Center.

National Digestive Diseases Information Clearinghouse. (2003). Lactose intolerance [NIH Publication No. 03-2751].

National Library of Medicine. (updated 2004). Lactose intolerance. MedlinePlus Medical Encyclopedia.