Topic Overview
What is lactose intolerance?
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
problems.
Lactose intolerance is common in adults. It occurs more often in
First Nations peoples 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.
What causes lactose intolerance?
Lactose
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
temporary.
In rare cases, newborns are lactose-intolerant. A
person born with lactose intolerance cannot eat or drink anything with
lactose.
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.
What are the symptoms?
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:
- Bloating.
- Pain or
cramps.
- Gurgling or rumbling sounds in your
belly.
- Gas.
- Loose stools or
diarrhea.
- Throwing up.
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.
How is lactose intolerance diagnosed?
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
normally.
How is it treated?
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 non-dairy foods that contain calcium, including:
- Broccoli, okra, kale, collards, and turnip
greens.
- Canned sardines, tuna, and salmon.
-
Calcium-fortified juices and cereals.
- Calcium-fortified soy
products such as soy milk, tofu, and soybeans.
- Almonds.
Frequently Asked Questions
Learning about lactose intolerance: | |
Being diagnosed: | |
Getting treatment: | |
Ongoing concerns: | |
Symptoms
Symptoms of
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:
- Bloating.
- Pain or cramps in the
lower belly.
- Gurgling or rumbling sounds in the lower
belly.
- Gas.
- Loose stools or diarrhea. Sometimes the
stools are foamy.
- Throwing up.
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
rash, vomiting,
dehydration, weakness and irritability, and slow
weight gain.
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.
Examinations and Tests
If your doctor thinks you have
lactose intolerance, he or she will
ask questions about your medical history and do a physical examination. Before
making a diagnosis, your doctor may ask that you avoid dairy products for a
short time to see if your symptoms improve.
To confirm a
diagnosis, your doctor may order a:
- Hydrogen breath test. This is the most accurate
lactose intolerance test. Before the test, you need to avoid certain foods and
medicines and cigarettes. On the day of the test, you will drink a liquid that
contains lactose and then breathe into a machine several times over a couple of
hours. If the hydrogen levels in your breath are high, you may have lactose
intolerance. This test is not usually done on babies and very young children,
because it can cause severe diarrhea.
- Lactose tolerance test. This test measures your
blood sugar after you eat or drink lactose. After midnight on the night before
the test, you should not eat or drink anything. On the day of your test, you
will drink a liquid that contains lactose, which may cause gas or pain in your
belly. Then your blood will be tested every 30 minutes for 2 hours. If your
blood sugar levels do not rise, you may be lactose-intolerant. This test is not
done on people who have diabetes. And it is usually not done on babies and very
young children.
Treatment Overview
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 and most
can avoid discomfort and still eat or drink some milk products throughout the
day.
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:
Approximate lactose and calcium in some foods 1 | Food | Serving size | Lactose (g) | Calcium (mg) |
|---|
Milk, fat-free | 250 mL (1 cup) | 12.5 | 300 |
Cheddar cheese | 30 g (1 oz) | 0.07 | 204 |
Cottage cheese, 2% milkfat | 125 mL (0.5 cup) | 3 | 100 |
Cream cheese | 30 g (1 oz) | 0.9 | 28 |
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
drink more.
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
symptoms.
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
non-dairy creamers in your coffee. But keep in mind that non-dairy 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
for you.
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."
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:
- Dry milk
solids.
- Whey.
- Curds.
- Milk
by-products.
- Non-fat dry milk powder.
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
non-dairy foods that contain calcium, including:
- Broccoli, okra, kale, collards, and turnip
greens.
- Canned sardines, tuna, and salmon.
- Calcium-fortified juices and
cereals.
- Calcium-fortified soy products such as soy milk, tofu, and
soybeans.
- Almonds.
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
a
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
or vomiting.
What to think about
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
attention.
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.
Other Places To Get Help
Organizations
| Canadian Digestive Health Foundation |
| Web Address: | www.cdhf.ca |
| |
The Canadian Digestive Health Foundation provides
educational information about digestive diseases and supports research into
their causes and treatment. |
|
| Dietitians of Canada |
| 480 University Avenue |
| Suite 604 |
| Toronto, ON M5G 1V2 |
| Phone: | (416) 596-0857 |
| Fax: | (416) 596-0603 |
| Email: | centralinfo@dietitians.ca |
| Web Address: | www.dietitians.ca |
| |
The Dietitians of Canada website provides a wide range
of food and nutrition information, including fact sheets on frequently asked
food and diet questions, quizzes and other tools to assess your diet habits,
and meal planning guides. |
|
References
Citations
- U.S. Department of Agriculture, Agricultural Research Service (2010). Nutrient data laboratory. USDA National Nutrient Database for Standard Reference, Release 23. Available online: http://www.ars.usda.gov/ba/bhnrc/ndl.
Other Works Consulted
- American Academy of Pediatrics (2009). Lactose section of Carbohydrate and dietary fiber. In Pediatric Nutrition Handbook, 6th ed., pp. 346–348. Elk Grove Village, IL: American Academy of Pediatrics.
- Hogenauer C, Hammer HF (2010). Lactose malabsorption and intolerance section of Maldigestion and malabsorption. In M Feldman et al., eds., Sleisenger and Fordtran’s Gastrointestinal and Liver Disease, 9th ed., vol. 2, pp. 1754–1755. 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.
Credits
| By | Healthwise Staff |
|---|
| Primary Medical Reviewer | E. Gregory Thompson, MD - Internal Medicine |
|---|
| Primary Medical Reviewer | Brian D. O'Brien, MD - Internal Medicine |
|---|
| Specialist Medical Reviewer | Rohit K Katial, MD - Allergy and Immunology |
|---|
| Last Revised | September 20, 2011 |
|---|
