Home > Health & Wellness > Health Library > Lactose Intolerance
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:
Many people who have gas, belly pain, bloating, and
diarrhea suspect they may be lactose-intolerant. The best way to check this is
to avoid eating all milk and dairy products to see if your symptoms go away. If
they do, then you can try adding small amounts of milk products to see if your
symptoms come back.
If you feel sick after drinking a glass of
milk one time, you probably do not have lactose intolerance. But if you feel
sick every time you have milk, ice cream, or another dairy product, you may
have lactose intolerance.
Sometimes people who have never had
problems with milk or dairy products suddenly have lactose intolerance. This is
more common as you get older.
If you think you might have lactose
intolerance, talk with your doctor. He or she can make sure that your symptoms
are caused by lactose intolerance and not by another problem.
A doctor can
usually tell whether you have lactose intolerance by asking questions about
your symptoms. He or she may also ask that you avoid dairy products for a short
time to see if your symptoms improve.
Sometimes doctors order a
hydrogen breath test or a blood sugar test to confirm
the diagnosis. These simple tests check to see if you are digesting lactose
There is no cure for lactose
intolerance. But you can treat your symptoms by limiting or avoiding milk
products. Some people use milk with reduced lactose, or they substitute soy
milk and soy cheese for milk and milk products. Some people who are
lactose-intolerant can eat yogurt without problems, especially yogurt with live
cultures. You can also take dietary supplements called lactase products that
help digest lactose. In time, most people who have lactose intolerance get to know
their bodies well enough to avoid symptoms.
One of the biggest
concerns for people who are lactose-intolerant is making sure they get enough
of the nutrients found in milk products, especially calcium. Calcium is most
important for children, teens, pregnant women, and women after menopause. There
are many nondairy foods that contain calcium, including:
Learning about lactose intolerance:
lactose intolerance can be mild or severe, depending
on how much lactase your body makes. Symptoms usually begin 30 minutes to 2
hours after eating or drinking milk or milk products. If you have lactose
intolerance, your symptoms may include:
Many people think they are lactose-intolerant, because the
symptoms of lactose intolerance are very common symptoms. If you feel sick
after drinking a glass of milk one time, you probably do not have lactose
intolerance. But if you feel sick every time you have milk, ice cream, or
another dairy product, you may have lactose intolerance.
Sometimes people who have never had problems with milk or dairy products
suddenly have lactose intolerance. This is more common as you get older.
Symptoms of the most common type of lactose intolerance—adult
lactose intolerance—often start during the teen or adult years and continue
for life. Symptoms of acquired lactose intolerance last as long as the small
intestine does not make lactase.
In rare cases, newborns are
lactose-intolerant. Symptoms in newborns include severe foamy diarrhea, diaper
dehydration, weakness and irritability, and slow
Lactose intolerance is not the same thing as a food allergy to milk. Symptoms of a milk allergy are usually more severe than those from lactose intolerance. People who have a milk allergy cannot eat or drink any milk products. For more information, see the topic Food Allergies.
If you think you might have lactose intolerance, talk
it over with your doctor. Your doctor can make sure that your symptoms are
caused by lactose intolerance and not by another problem. Other conditions can
cause symptoms similar to those of lactose intolerance, including
irritable bowel syndrome,
inflammatory bowel disease, overuse of laxatives, and
problems digesting foods that contain
fructose and sorbitol.
If your doctor thinks you have
lactose intolerance, he or she will
ask questions about your medical history and do a physical exam. Before
making a diagnosis, your doctor may ask that you avoid dairy products for a
short time to see if your symptoms improve. You may also be asked to bring in a sample
of your stool. The stool of a person who has lactose intolerance is usually loose or watery. It also can be foamy.
To confirm a
diagnosis, your doctor may order a:
If you think you have
lactose intolerance, it is a good idea to talk it over
with your doctor. Your doctor can make sure that your symptoms are caused by
lactose intolerance and not by another problem such as
irritable bowel syndrome,
inflammatory bowel disease, overuse of laxatives, or
problems digesting foods that contain
fructose or sorbitol. Your doctor can also make sure
that your lactose intolerance is not related to another health problem.
After being diagnosed with lactose intolerance, you may feel relieved to
find out what has been causing your symptoms. You may also feel frustrated by
having to deal with this condition for the rest of your life. You may find it
reassuring to know that there are many people who have lactose intolerance. Most
can avoid discomfort and still eat or drink some milk products throughout the
There are different ways to live with lactose intolerance.
What works for one person may not work for another. Because there is no cure
for lactose intolerance, controlling your symptoms is mostly up to you. The
following tips can help you prevent symptoms of lactose intolerance.
Limit the amount of milk and milk products in your diet. Most people can have about 10 g of lactose each day.
This can be a glass of whole, low-fat, or fat-free milk, for
example. All milk contains the same amount of lactose. Other milk
products contain different amounts of lactose:
8 fl oz (240 mL)
1 oz (30 g)
Cottage cheese, 2% milk fat
4 oz (113 g)
Foods with less lactose, such as Swiss or cheddar cheese,
may not cause problems. If you are not sure whether a milk product causes
symptoms, try a small amount and wait to see how you feel before you eat or
Eat or drink milk and milk products along with other foods. For some people, combining a solid food (like
cereal) with a dairy product (like milk) may reduce or eliminate
Spread milk or milk products throughout the day. Many people who are lactose-intolerant find it helpful to eat
small amounts of lactose-containing products throughout the day instead of
larger amounts all at one time.
Eat or drink milk and milk products that have reduced lactose. In most grocery stores, you
can buy milk with reduced lactose. Some people like buying this kind of milk
and find that it helps control their symptoms. Others find that it tastes too
sweet or is too expensive. People who have
diabetes may find that lactose-reduced milk raises
their blood sugar levels higher than normal.
Eat or drink other foods instead of milk and milk products. You can
substitute soy milk and soy cheese for milk and milk products. You can also use
nondairy creamers in your coffee. But keep in mind that nondairy creamers do
not contain the same vitamins and minerals as milk, and they may contain more
fat than milk contains.
Use lactase products. Lactase products are dietary supplements that help you digest lactose.
There are many different brands of lactase products. Some are pills that you
chew (such as Lactaid) before you eat or drink milk products. Others are
liquids that you can add to milk 24 hours before you drink it. Some foods have extra lactase added to them. Because products
and brands are different, you may want to try a few to see which ones work best
Eat yogurt with live cultures (not pasteurized). Some people who are lactose-intolerant can eat yogurt
without having problems, especially yogurt that contains live cultures.
This type of yogurt can help people digest lactose. All
yogurts are made with live cultures, but many yogurts go through a process
called "heat treatment" that kills the bacteria. If you want to be sure you are
buying yogurt that still contains live cultures, check the label for the words
"active yogurt cultures," "living yogurt cultures," or "contains active
cultures." It's best to try a small amount of different brands of yogurt to see which ones work best for you.
If you have severe lactose intolerance, you may need to avoid lactose
completely. Some medicines and many prepared foods contain lactose. Examples of
prepared foods with lactose include breads and baked goods; breakfast cereals
and instant breakfast drinks; instant potatoes and instant soups; pancake,
cookie, and biscuit mixes; margarine and salad dressings; candies, milk
chocolate, and other snacks. Be sure to read labels for lactose and for
lactose's "hidden" names, such as:
One of the biggest concerns for people who are
lactose-intolerant is making sure they get enough of the nutrients found in
milk products, especially
calcium. Calcium is especially important for women,
because it keeps bones strong and reduces the risk of
osteoporosis. There are many
nondairy foods that contain calcium, including:
To absorb calcium, your body needs vitamin D. Most people
get enough vitamin D by being out in the sun for short periods of time each
day. Vitamin D is also found in fortified orange juice, fortified soy
milk, oily fish (such as salmon), egg yolks, and liver.
If you don't know whether you are
getting enough calcium, vitamin D, and other important nutrients found in milk
products, such as magnesium, potassium, protein, and riboflavin, talk to your
doctor. He or she may recommend that you take a calcium supplement or meet with
registered dietitian to make sure you are getting
enough of certain vitamins and minerals.
You should also talk with
your doctor if your symptoms do not go away with treatment, if they get worse,
or if you have other symptoms, such as a fever, chills, or severe belly pain
Lactose intolerance in
newborns of normal birth weight and in babies is rare. But if your child has
symptoms of lactose intolerance, see your doctor right away. Diarrhea is
very dangerous because it can lead to
dehydration, a serious problem that requires immediate
Babies who are only fed breast milk do not develop
lactose intolerance, because breast milk contains
lactase, the enzyme that helps digest milk sugar. If
your baby is
formula-fed and develops lactose intolerance, you can
switch to a formula made without lactose. In rare cases, a baby may have a
reaction to the proteins in milk, which is a different condition called
sensitivity to milk protein.
This clearinghouse is a service of the U.S. National
Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the
U.S. National Institutes of Health. The clearinghouse answers questions;
develops, reviews, and sends out publications; and coordinates information
resources about digestive diseases. Publications produced by the clearinghouse
are reviewed carefully for scientific accuracy, content, and readability.
U.S. Department of Agriculture, Agricultural Research Service (2012). Nutrient data laboratory. USDA National Nutrient Database for Standard Reference, Release 25. Available online: http://ndb.nal.usda.gov.
Other Works Consulted
American Academy of Pediatrics (2009). Carbohydrate and dietary fiber. In Pediatric Nutrition Handbook, 6th ed., pp. 343–356. Elk Grove Village, IL: American Academy of Pediatrics.
Hogenauer C, Hammer HF (2010). Maldigestion and malabsorption. In M Feldman et al., eds., Sleisenger and Fordtran's Gastrointestinal and Liver Disease, 9th ed., vol. 2, pp. 1735–1767. Philadelphia: Saunders.
Whitney E, Rolfes SR (2011). Digestion and absorption of carbohydrates section of The carbohydrates: Sugars, starches, and fibers. In Understanding Nutrition, 12th ed., pp. 105–107. Belmont, CA: Wadsworth.
June 28, 2013
E. Gregory Thompson, MD - Internal Medicine & Rohit K Katial, MD - Allergy and Immunology
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