means the body cannot easily digest lactose, a type of natural sugar found in
milk and dairy products. This is not the same thing as a food allergy to milk.
When lactose moves through the
large intestine (colon) without being properly digested, it can cause
uncomfortable symptoms such as gas, belly pain, and bloating. Some people who have
lactose intolerance cannot digest any milk products. Others can eat or
drink small amounts of milk products or certain types of milk products without
Lactose intolerance is common in adults. It occurs more often in
Native Americans and people of Asian, African, and South American descent than
among people of European descent.
A big challenge for people who
are lactose-intolerant is learning how to eat to avoid discomfort and to get
enough calcium for healthy bones.
intolerance occurs when the
small intestine does not make enough of an
enzyme called lactase. Your body needs lactase to
break down, or digest, lactose.
Lactose intolerance most commonly
runs in families, and symptoms usually develop during the teen or adult years.
Most people with this type of lactose intolerance can eat some milk or dairy
products without problems.
Sometimes the small intestine stops
making lactase after a short-term illness such as the
stomach flu or as part of a lifelong disease such as
cystic fibrosis. Or the small intestine sometimes stops
making lactase after surgery to remove a part of
the small intestine. In these cases, the problem can be either permanent or
In rare cases, newborns are lactose-intolerant. A
person born with lactose intolerance cannot eat or drink anything with
Some premature babies have temporary lactose intolerance
because they are not yet able to make lactase. After a baby begins to make
lactase, the condition typically goes away.
Symptoms of lactose
intolerance can be mild to severe, depending on how much lactase your body
makes. Symptoms usually begin 30 minutes to 2 hours after you eat or drink milk
products. If you have lactose intolerance, your symptoms may include:
- Pain or
- Gurgling or rumbling sounds in your
- Loose stools or
- Throwing up.