Lactose Intolerance Information

Lactose Intolerance Information

People who are lactose intolerant have trouble digesting lactose, the natural sugar found in milk and milk products. They have this condition because their bodies do not make enough lactase. Lactase is an enzyme made in the small intestine. Lactase breaks down lactose into simpler forms of sugar, which are easily absorbed into the blood. Undigested lactose can lead to unpleasant digestive symptoms


People vary in their degree of lactose intolerance. Most people who are lactose intolerant are able to consume some lactose without symptoms. However, many people who think they are lactose intolerant avoid milk products and do not consume enough calcium and vitamin D,1 which are nutrients important to bone health. Getting enough calcium is especially important for children and teens, who are at the ages when bones grow the most.

Symptoms of lactose intolerance include:

*Bloating
*Diarrhea
*Gas
*Stomach pain or cramps

Symptoms begin about 30 minutes to 2 hours after eating or drinking foods containing lactose. Symptoms can be mild or severe. The severity of the symptoms usually depends on both the amount of lactose consumed and the amount of lactase in a person's body.

How many people are lactose intolerant?
The true number of people with lactose intolerance is not known. Many people who have symptoms of lactose intolerance have not been diagnosed with the condition. Many people who think they are lactose intolerant do not have difficulty digesting lactose. Many people who have difficulty digesting lactose do not get symptoms.

Who gets lactose intolerance and who is at risk for it?
Lactose intolerance can affect anyone. In the United States, it is most common among:

African Americans
Asian Americans
Hispanic Americans
Native Americans
Lactose intolerance is uncommon in young children because most infants are born with enough lactase. But for many people, the amount of lactase in their bodies decreases over a lifetime.

Preterm infants born before 34 weeks' gestation can have low lactase levels because their digestive tract is not fully developed.


Many people think that they or their children are lactose intolerant without being tested or diagnosed. As a result, many people avoid or greatly limit their intake of dairy products, which are rich in calcium and vitamin D. These nutrients help to build strong bones. Most people who are lactose intolerant are able to consume some amount of lactose without symptoms.

It's not always easy to tell based on symptoms alone whether a person has lactose intolerance or another condition. Many common health problems have similar symptoms. For instance, lactose intolerance has many of the same symptoms as irritable bowel syndrome (IBS); however, IBS can also cause constipation.

If lactose intolerance is suspected, the person may be asked to stop eating or drinking foods that contain lactose for a brief time. If the symptoms go away, then this information may be all a health care provider needs for a diagnosis. The following tests also can help diagnose lactose intolerance:

Hydrogen breath test. For this test, a person drinks a beverage that has lactose in it. Then, the hydrogen level in the breath is measured at set time intervals. Hydrogen gas is formed when lactose is not digested, so high breath hydrogen is a likely sign of problems digesting lactose.

Lactose intolerance test. For this test, blood samples are taken before and after a person drinks a beverage that contains lactose. The amount of sugar (glucose) in the blood is measured. Levels that do not change can suggest problems digesting lactose. The hydrogen breath test is preferred over this test.

Stool acidity test. This test is used for infants and young children. The stool is checked for certain acids that form when lactose is not digested. Glucose in the stool also suggests problems digesting lactose.


No treatment can change the body's ability to make lactase. But most people who have problems digesting lactose can take steps to minimize symptoms without giving up milk and milk products completely. Studies show that the following strategies can help:

Drink low-fat milk or fat-free milk in servings of one cup or less.

Drink low-fat milk or fat-free milk with other food, such as with breakfast cereal, instead of on an empty stomach.

Eat dairy products other than milk, such as low-fat or fat-free hard cheeses or cottage cheese, or low-fat or fat-free ice cream or yogurt. These foods contain less lactose per serving compared with milk and may cause fewer symptoms.

Choose reduced-lactose milk and milk products, which have the same amount of calcium as regular milk.

Use over-the-counter pills or drops that contain lactase enzyme.

With some trial and error, people with lactose intolerance can learn which milk products and how much of them their bodies can handle. Most people should not avoid milk and milk products completely because they provide calcium, vitamin D, and other key nutrients needed for bone and overall health. People who are lactose intolerant should make sure they get enough of these key nutrients from other sources if they don't get them from dairy foods.


Not having enough lactase in the body is the cause of lactose intolerance. The names for the three types of lactose intolerance describe why a person may not have enough lactose:

Primary lactose intolerance. This type develops in people who were once able to fully digest lactose. It is the most common type. Almost all infants make enough lactase to fully digest lactose found in human milk and infant formulas. But at some point after being weaned, most children in the world begin to make less lactase. Most people with primary lactose intolerance can consume some milk products without having symptoms.

Secondary lactose intolerance. This type results from damage to the intestines, such as from severe illness or disease.

Congenital lactose intolerance. Infants born with this rare type make no lactase at all. It is not uncommon for secondary lactose intolerance to be misdiagnosed during the newborn period as congenital lactose intolerance.