Jessie was so embarrassed! About an hour after chowing down on
pizza and ice cream with a group of friends, her stomach suddenly
started rumbling, and she started farting. Then Jessie's
stomach began to ache and she had to run to the restroom every few
minutes. In the excitement of an afternoon hanging out at the mall,
Jessie had forgotten to watch her dairy intake. Jessie has lactose
intolerance and her symptoms flare up when she eats more dairy than
her body can handle.
What Is Lactose Intolerance and What Causes It?
Lactose intolerance is the inability to digest a sugar called
lactose
that is found in milk and dairy products.
Normally when a person eats something containing lactose, an
enzyme in the small intestine called
lactase
breaks down lactose into simpler sugar forms called
glucose
and
galactose
. These simple sugars are then easily absorbed into the bloodstream
and turned into energy - fuel for our bodies.
People with lactose intolerance do not produce enough of the
lactase enzyme to break down lactose. Instead, undigested lactose
sits in the gut, causing gas, bloating, and stomach cramps. When
the intestine cannot absorb the lactose-containing foods, it can
lead to diarrhea.
Lactose intolerance is fairly common. It seems to affect guys
and girls equally. Some ethnic groups are more likely to be
affected than others because their diets traditionally include
fewer dairy products: Almost all Asians and Native Americans are
lactose intolerant, and up to 80% of African Americans and Hispanic
Americans also have symptoms of lactose intolerance. Their
ancestors did not eat dairy foods, so their bodies were not
prepared to digest dairy, and they passed these genes on from
generation to generation.
Little kids are less likely to have lactose intolerance. But
many people eventually become lactose intolerant in adulthood -
some while they are still teens. Some health care providers view
lactose intolerance as a normal human condition and therefore
don't really consider it a disease.
Who Gets Lactose Intolerance?
A person may be or may become lactose intolerant for different
reasons:
-
Ethnic background.
People of Asian, African, Native American, and Hispanic
backgrounds are more likely to develop lactose intolerance at a
young age.
-
Other problems with the digestive tract.
People with irritable bowel syndrome or Crohn's disease have
a reduced level of the lactase enzyme. Those with other diseases
of the gastrointestinal tract, such as celiac disease, can also
have problems digesting lactose.
-
Medications.
Certain antibiotics can trigger temporary lactose intolerance by
interfering with the intestine's ability to produce the
lactase enzyme.
-
Infection.
After a bout of infectious diarrhea, some kids can develop a
temporary lactose intolerance that usually improves after a few
days or weeks.
-
Age.
As people get older, their bodies usually stop producing the
lactase enzyme, and most people will naturally become lactose
intolerant over time.
What Happens When Someone Has Lactose Intolerance?
People with lactose intolerance may have a variety of symptoms.
It all depends on how much dairy or how many milk-containing foods
the person eats and how little lactase the body produces.
Usually within 30 minutes to 2 hours after eating, someone with
lactose intolerance will experience nausea, stomach cramps,
bloating, gas, and diarrhea. This can be unpleasant, not to mention
embarrassing if you're at school or out with friends.
Because many people may think they're lactose intolerant
when they really aren't, it helps to see a doctor who can
diagnose the condition correctly and advise you on ways to manage
it.
How Do Doctors Diagnose It?
If your doctor suspects you might be lactose intolerant, he or
she will take your
medical history
by asking about any concerns and symptoms you have, your past
health, your family's health, any medications you're
taking, any allergies you may have, and other issues. Your doctor
will also give you a
physical examination
.
Doctors can test for lactose intolerance by using the hydrogen
breath test. Normally very little hydrogen gas is detectable in the
breath. However, undigested lactose in the colon ferments (breaks
down) and produces various gases, including hydrogen.
If your doctor decides to give you a hydrogen breath test,
you'll be asked to blow into a tube for a beginning
sample. You'll then swallow a drink or eat a food with lactose
in it, wait a while, and breathe into the tube again. The hydrogen
level of the sample is then checked.
Doctors also can find out if you're able to digest lactose
by testing for the presence of lactase with an
endoscopy
. During this procedure, doctors view the inside of the intestines
by inserting a long tube with a light and a tiny camera on the end
into the mouth or anus. A doctor can then take tissue samples and
pictures of the inside of your gut and look for clues to why
you've been having problems with what you're eating.
Living With Lactose Intolerance
Lactose intolerance is a very individual condition and it's
often easy to manage if you're in tune with your body.
Everyone's different, but most people with lactose intolerance
are able to eat a small amount of dairy. The trick is to eat dairy
products in combination with other foods that don't contain
lactose and not eat too much dairy at once. It can also help to
keep a food diary to learn which foods your body can or can't
tolerate.
Dairy foods are the best source of calcium, a mineral that's
important for bone growth. Because growing teens need about 1,300
milligrams (mg) of calcium each day, the American Academy of
Pediatrics (AAP) recommends that even teens who have lactose
intolerance continue to include some dairy in their diet.
Foods like cheese or yogurt may be easier to digest than milk,
so try a cup of yogurt for dessert or add a piece of cheese to your
sandwich. Lactose-free milk is also a great way to get calcium in
your diet without the problems that can come with lactose.
Teens with the most severe symptoms of lactose intolerance may
have to avoid all dairy products. It's extra important that
these teens find other good calcium sources, so talking to a
registered dietitian is a good idea. Dietitians are trained in
nutrition and they can help people who are lactose intolerant come
up with eating alternatives and develop a well-balanced diet that
provides lots of calcium for developing strong bones.
Here are some tips for dealing with lactose intolerance:
- Choose lactose-reduced or lactose-free milk.
- Take a lactase enzyme supplement (such as Lactaid) just
before you eat dairy products. These can be taken in drops or
tablets and even added directly to milk (they tend to make milk
taste a bit sweeter if left for a long time).
- When you do drink milk or eat lactose-containing foods, eat
other non-lactose foods at the same meal to slow digestion and
avoid problems. (For example, if you are going to have a
milkshake, don't drink it by itself. Have something else with
it - like a healthy sandwich.)
- Drink juices that are fortified with calcium.
- Eat a variety of dairy-free foods that are rich in calcium,
such as broccoli, beans, tofu, or soy milk. Consider hard cheeses
such as cheddar, which are lower in lactose.
- Yogurts that contain active cultures are easier to digest and
much less likely to cause lactose problems.
- Learn to read food labels. Lactose is added to some boxed,
canned, frozen, and prepared foods like bread, cereal,
lunchmeats, salad dressings, mixes for cakes and cookies, and
coffee creamers. Be aware of certain words that may mean the food
has lactose in it: butter, cheese, cream, dried milk, milk
solids, powdered milk, and whey, for example.
Reviewed by:
Larissa Hirsch, MD
Date reviewed: September 2006
Originally reviewed by:
John Yu Chuan Tung, MD, MBBS, MRCP
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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