Lactose Intolerance
What is lactose intolerance?
Lactose intolerance is a condition caused by a lack of an enzyme called
lactase. Inadequate amounts of lactase cause the body to be unable to
digest lactose, a sugar found in milk products.
Lactase is normally produced in the small intestine where it breaks
lactose down into a form that can be absorbed by the blood. A lack of
lactase can cause uncomfortable symptoms for some people. Those who do
exhibit the symptoms are said to be lactose intolerant.
Thirty to 50 million Americans (adults and children) are lactose
intolerant. The disorder affects some populations more than others:
- Seventy-five percent of all African-Americans and Native Americans
are lactose intolerant.
- Ninety percent of Asian-Americans are lactose intolerant.
Lactose intolerance is least common among people with a northern
European heritage.
What causes lactose intolerance?
Digestive diseases or injuries to the small intestine can reduce the
amount of enzymes produced and is the usual cause of lactose intolerance
in young children. However, most cases of lactose intolerance develop over
a period of many years in adolescents and adults.
What are the symptoms of lactose intolerance?
The following are the most common symptoms for lactose intolerance.
However, each individual may experience symptoms differently. Common
symptoms, which begin about 30 minutes to two hours after consuming foods
or beverages containing lactose, may include:
- nausea
- cramps
- bloating
- gas
- diarrhea
The severity of symptoms varies depending on the amount of lactose
consumed and the amount each individual can tolerate.
The symptoms of lactose intolerance may resemble other conditions or
medical problems. Always consult your child's physician for a diagnosis.
How is lactose intolerance diagnosed?
The most common diagnostic tests (performed on an outpatient basis at the
hospital, clinic, or physician's office) used to measure the absorption of
lactose in the digestive system include the following:
- lactose tolerance test
This test measures the absorption of lactose in the digestive
system. After fasting, the patient drinks a liquid that contains
lactose. The diarrheal stools are then tested for lactose for the next
24 hours.
Undigested lactose fermented by bacteria in the colon creates lactic
acid and other fatty acids, which can be detected in a stool sample,
along with glucose as a result of unabsorbed lactose.
- hydrogen breath test
The patient drinks a lactose-heavy beverage. The breath is then
analyzed at regular intervals to measure the amount of hydrogen.
Undigested lactose in the colon is fermented by bacteria, resulting in
the production of various gases, including hydrogen. When high levels of
hydrogen are present in the breath, improper digestion of lactose is
diagnosed.
Treatment for lactose intolerance:
Specific treatment for lactose intolerance will be determined by your
child's physician based on:
- your child's age, overall health, and medical history
- the extent of the disease
- your child's tolerance for specific medications, procedures, or
therapies
- the expectations for the course of the disease
- your opinion or preference
Although, there is not a treatment to improve the body's ability to
produce lactase, symptoms caused by lactose intolerance can often be
controlled with a proper diet. In addition, lactase enzymes may be
suggested by your child's physician.
Calcium for children with lactose intolerance:Calcium is essential for the growth and repair of bones
throughout life and has been suggested as a preventive measure for other
diseases. Because milk and other dairy products are a major source of
calcium, parents must be concerned with lactose intolerant children and
teenagers getting enough calcium in a diet that includes little or no
milk.
The recommended daily dietary allowance (RDA) for calcium, released in
1997 by the National Institutes of Medicine, varies by age group.
- 0 to 6 months, 210 mg
- 6 months to 1 year, 270 mg
- 1 to 3 years, 500 mg
- 4 to 8 years, 800 mg
- 9 to 18 years, 1,300 mg
Many nondairy foods are high in calcium, including:
- green vegetables, such as broccoli and kale (Swiss chard, spinach,
and rhubarb are not listed because the body cannot use their calcium
content - they contain substances called oxalates, which inhibit calcium
absorption)
- fish with soft, edible bones, such as salmon and sardines
- yogurt with active cultures may be a good source of calcium for many
people with lactose intolerance - evidence shows that the bacterial
cultures used in making yogurt produce some of the lactase enzyme
required for proper digestion
Your child's physician may prescribe a calcium supplement if your child
is unable to get enough calcium from his/her diet.
Vitamin D is necessary for the body to absorb calcium, therefore, your
child's diet should provide an adequate supply of vitamin D. Sources
of vitamin D include eggs and liver. Sunlight is also a good source
of vitamin D.
More Information
Schneider Children's Hospital Division
of Gastroenterology
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