Lactose intolerance (patient information)
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Assistant Editor(s)-In-Chief: Meagan E. Doherty
Overview
Lactose is a type of sugar found in milk and other dairy products. An enzyme called lactase is needed by the body to digest lactose. Lactose intolerance develops when the small intestine does not make enough of this enzyme. People sometimes confuse lactose intolerance with cow’s milk intolerance because the symptoms are often the same. However, lactose intolerance and cow’s milk intolerance are not related. Being intolerant to cow’s milk is an allergic reaction triggered by the immune system. Lactose intolerance is a problem caused by the digestive system.
What are the symptoms of Lactose intolerance?
Symptoms often occur 30 minutes to 2 hours after having milk products. Symptoms may be worse when you consume large amounts.
Symptoms include:
What causes Lactose intolerance?
.Babies' bodies make the lactase enzyme so they can digest milk, including breast milk.
- Babies born too early (premature) sometimes have lactose intolerance.
- Children who were born at full term often do not show signs of the problem before they are 3 years old.
Lactose intolerance is very common in adults. It is rarely dangerous. About 30 million American adults have some degree of lactose intolerance by age 20.
- In white people, lactose intolerance often develops in children older than age 5. This is the age when our bodies may stop making lactase.
- In African Americans, the problem can occur as early as age 2.
- The condition is very common among adults with Asian, African, or Native American heritage.
- It is less common in people of northern or western European background, but still may occur.
An illness that involves or injures your small intestine may cause less of the lactase enzyme to be made. Treatment of these illnesses may improve the symptoms of lactose intolerance. These may include:
- Surgery of the small intestine
- Infections in the small intestine (this is most often seen in children)
- Diseases that damage the small intestines, such as celiac sprue or crohn disease
Babies may be born with a genetic defect and are not able to make any of the lactase enzyme.
Who is at highest risk?
Between 30 and 50 million Americans are lactose intolerant and certain ethnic and racial populations are more affected than others. Up to 80 percent of African Americans, 80 to 100 percent of American Indians, and 90 to 100 percent of Asian Americans are lactose intolerant. The condition is least common among people of northern European descent.
Babies that are born prematurely are also more likely to be lactose intolerant, because lactase levels do not increase until the third trimester of a woman’s pregnancy.
Diagnosis
Lactose intolerance can be hard to diagnose based on symptoms alone. People sometimes think they suffer from lactose intolerance because they have the symptoms associated with the disorder, not knowing other conditions such as irritable bowel syndrome can cause similar symptoms. A doctor can use tests to diagnose lactose intolerance but may first recommend eliminating cow’s milk from the diet to see if the symptoms go away.
The most common tests used to measure the absorption of lactose in the digestive system are the lactose tolerance, hydrogen breath, and stool acidity tests.
- The Lactose Tolerance Test: This test requires fasting (not eating) before the test and then drinking a liquid that contains lactose. Several blood samples are then taken over a 2-hour period to measure the person’s blood glucose (blood sugar) level. These measures indicate how well the body is able to digest lactose.
Normally, when lactose reaches the digestive system, the lactase enzyme breaks it down into glucose and galactose. The liver then changes the galactose into glucose, which enters the bloodstream and raises the person’s blood glucose level. If, however, lactose is incompletely broken down, the blood glucose level does not rise and a diagnosis of lactose intolerance is confirmed.
- The Hydrogen Breath Test: This test measures the amount of hydrogen in a person’s breath. Very little hydrogen is normally detectable. However, undigested lactose in the colon is fermented by bacteria and produces various gases, including hydrogen. The hydrogen is absorbed from the intestines, carried through the bloodstream to the lungs, and exhaled. In this test, the person drinks a lactose-loaded beverage and the breath is analyzed at regular intervals. Raised levels of hydrogen in the breath indicate improper digestion of lactose. Certain foods, medications, and cigarettes can affect the accuracy of the test and should be avoided before taking the test. People should check with their doctor to make sure they are not taking medications that may interfere with test results.
The lactose tolerance and hydrogen breath tests are not given to infants younger than 6 months of age. A large lactose load can be dangerous prior to this age, as infants are more likely to become dehydrated from diarrhea that can be caused by lactose intolerance.
- Stool Acidity Test: This test may be used for infants and young children to measure the amount of acid in their stool. Undigested lactose fermented by bacteria in the colon creates lactic acid and other fatty acids that can be detected in a stool sample. Glucose may also be present in the sample as a result of unabsorbed lactose in the colon.
Diseases With Similar Symptoms
- Irritable bowel syndrome
- Inflammatory bowel disease
- Overuse of laxatives
- Problems digesting foods that contain fructose and sorbitol.
When to seek urgent medical care?
Lactose intolerance is not serious.
Call your provider if:
- You have an infant younger than 2 or 3 years old who has symptoms of lactose intolerance.
- Your child is growing slowly or not gaining weight.
- You or your child has symptoms of lactose intolerance and you need information about food substitutes.
- Your symptoms get worse or do not improve with treatment.
- You develop new symptoms.
Treatment options
Cutting down your intake of milk products that contain lactose from your diet most often eases symptoms. Also look at food labels for hidden sources of lactose in nonmilk products (including some beers) and avoid these.
Most people with low lactase level can drink up to one half cup of milk at one time (2 to 4 ounces or 60 to 120 milliliters) without having symptoms. Larger servings (more than 8 ounces or 240 mL) may cause problems for people with the deficiency.
Milk products that may be easier to digest include:
- Buttermilk and cheeses (these foods contain less lactose than milk)
- Fermented milk products, such as yogurt
- Goat's milk
- Ice cream, milkshakes, and aged or hard cheeses
- Lactose-free milk and milk products
- Lactase-treated cow's milk for older children and adults
- Soy formulas for infants younger than 2 years
- Soy or rice milk for toddlers
You can add lactase enzymes to regular milk. You can also take these enzymes as capsules or chewable tablets. There are also many lactose-free dairy products available.
Not having milk and other dairy products in your diet can lead to a shortage of calcium, vitamin D, riboflavin, and protein. You need 1,000 to 1,500 mg of calcium each day depending on your age and gender. Some things you can do to get more calcium in your diet are:
- Take calcium supplements with Vitamin D. Talk to your health care provider about which ones to choose.
- Eat foods that have more calcium (such as leafy greens, oysters, sardines, canned salmon, shrimp, and broccoli).
- Drink orange juice with added calcium.
Where to find medical care for Lactose intolerance?
Directions to Hospitals Treating Lactose intolerance
What to expect (Outook/Prognosis)?
Symptoms most often go away when you remove milk, other dairy products, and other sources of lactose from your diet. Without dietary changes, infants or children may have growth problems.