Lactose Intolerance
Introduction
Lactose intolerance is when the body is unable to digest the sugar lactose found in
dairy products. The condition is also known as lactase deficiency.
Lactose intolerance is usually not serious. It is estimated that 70 to 75% of the world’s
population has various degrees of lactose intolerance.
This reference summary will help you understand lactose intolerance. It discusses the
causes, symptoms and treatment options. A special section lists food with lactose.
Lactose Intolerance
Lactose is a type of sugar found in milk and other
dairy products. People with lactose intolerance
are not able to fully digest lactose.
An enzyme called lactase is created in the small
intestine. An enzyme is a compound that breaks
down other substances or speeds up chemical
reactions in the body. Lactase breaks down
lactose so that the body can absorb it. Lactose intolerance happens when the body
doesn’t make enough lactase.
If the body does not have enough of the enzyme lactase, lactose moves on into the
colon without being broken down and absorbed. Normal intestinal bacteria in the colon
interact with the lactose. This causes gas, diarrhea and the other symptoms of lactose
intolerance.
Lactose intolerance may develop later in life. It is not common in young children. This
is because the amount of the enzyme lactase created by the small intestines can
decrease over time.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/14/2017
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Lactose intolerance does not mean that you cannot have milk or dairy products. Most
people with lactose intolerance can tolerate some lactose in their diets. The symptoms
of lactase deficiency differ from person to person. Some may have severe symptoms
while others may have no symptoms.
Types
There are three types of lactose intolerance: primary,
secondary and congenital. Primary lactose intolerance is
caused by aging. Lots of lactase is produced during early
childhood because milk is the main source of nutrition. A
decrease in the amount of lactase is common as we age
and our diets change.
Secondary lactose intolerance is caused by an illness,
surgery or injury to the small intestine. These may cause
the small intestine to decrease the creation of lactase.
Congenital lactose intolerance is rare. It is when babies are born without the ability to
make lactase. They cannot tolerate their mother’s milk and have diarrhea from the time
they are born. Instead, they must have lactose-free formula.
Risk Factors
There are a few known risk factors that make you more likely to develop lactose
intolerance. One risk factor is age. Lactose intolerance is uncommon in young children.
It becomes more common as you get older. A person’s ethnicity may also increase his
or her risk of developing lactose intolerance. Caucasians are less likely than other
ethnicities to develop lactose intolerance.
Babies born prematurely are more likely to have lactose
intolerance. The enzyme lactase increases late in a
baby’s development in the womb. Premature babies may
be born before this happens.
Having celiac disease, Crohn’s disease or other diseases
that affect the small intestine also raises a person’s risk
for lactose intolerance. These diseases can harm the
small intestine, where lactase is made. Also, lactose intolerance can develop after
having radiation treatment to the abdomen. Radiation is often used to treat cancer.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/14/2017
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Symptoms
Symptoms of lactose intolerance are mostly mild. But they may become worse if a
large amount of food with lactose has been eaten.
Common symptoms of lactose intolerance
include:
• Gas or bloating.
• Abdominal cramps.
• Nausea.
• Diarrhea.
These symptoms usually happen anywhere
from 30 minutes to 2 hours after drinking milk
or eating milk products if they are caused by
lactose intolerance. You should check with your health care provider if you have the
symptoms of lactose intolerance. These symptoms may also be caused by other
illnesses.
Diagnosis
If you have the symptoms of lactose intolerance,
your health care provider will try to find out if you
have lactose intolerance or if something else is
causing your symptoms.
Your health care provider may begin by asking
you to eat less food containing the sugar lactose.
This means eating less dairy products. They may
also ask you to avoid these foods for a short time. If your symptoms improve, there are
three tests that can confirm the
diagnosis.
For the lactose intolerance test,
you will be asked to drink a liquid
that has a lot of lactose in it.
Your blood will be taken 2 hours
after drinking the liquid to
measure glucose, another sugar
in the body. If your body is not properly digesting lactose your glucose level will not
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/14/2017
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rise. This is because the enzyme lactase breaks down lactose into glucose and
galactose. These are simple sugars that are then
absorbed by the body.
Another test used to diagnose lactose
intolerance is the hydrogen breath test. You will
be asked to drink a liquid that has a lot of lactose
in it for this test. At different times, your health
care provider will measure the amount of
hydrogen in your breath.
Hydrogen levels in the breath are normally very
Hydrogen Breath Test
low. If you have lactose intolerance, hydrogen
levels in your breath rise after ingesting lactose because the undigested lactose moves
to the colon where it is acted on by bacteria causing the release of hydrogen that then
makes it into the breath.
The stool acidity test is usually used to diagnose lactose intolerance in young children.
The large amounts of lactose needed for the other tests may be dangerous for them.
This test measures lactic acid and other acids that are released if lactose reaches the
colon without being digested properly.
Treatment
The main treatment of lactose intolerance is to manage the
symptoms by changing the diet. Most people with lactose
intolerance do not have to give up milk or milk products.
You may be able to tolerate milk and milk products if you
drink small amounts of milk at a time. Four ounces is
recommended. Some people find that milk or milk products
are better tolerated if taken with a meal. Others can also
start with smaller amounts of milk products and gradually
increase the amount.
You can also eat milk products that are easier for people
with lactose intolerance to digest, such as yogurt and hard cheeses like cheddar and
Swiss. Other options include drinking lactose-free milk and milk products and soy or
rice milk. Also, cheeses and yogurt have less lactose than milk and may be easier to
digest.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/14/2017
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Milk and milk products are the best sources of calcium. You may need to look for other
sources of calcium to replace what you are losing as you change to a low-lactose diet.
You can also take lactase enzymes before you drink or eat milk products. This may
help with digestion and ease your symptoms. They can be added to regular milk or
taken as a pill.
Food with Lactose
Lactose is found in milk and all foods made with milk, such as:
• Ice cream.
• Cream.
• Butter.
• Cheese.
• Cottage cheese.
• Yogurt.
Rarely, people with lactose intolerance are bothered by small
amounts of lactose. Some boxed, canned, frozen, packaged and
prepared foods contain small amounts of lactose. These foods include:
• Bread and other baked goods.
• Waffles, pancakes, biscuits, cookies and mixes to make them.
• Prepared or frozen breakfast foods such as doughnuts, frozen waffles and
pancakes, toaster pastries and sweet rolls.
• Boxed breakfast cereals.
• Instant potatoes, soups and breakfast drinks.
• Potato chips, corn chips and other packaged snacks.
• Prepared meats, such as bacon, sausage, hot dogs and
lunch meats.
• Margarine.
• Salad dressings.
• Liquid and powdered milk-based meal replacements.
• Protein powders and bars.
• Candies.
• Nondairy liquid and powdered coffee creamers.
• Nondairy whipped toppings.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/14/2017
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Look for certain words on food labels. These words mean the
food has lactose in it:
• Milk.
• Lactose.
• Whey.
• Curds.
• Milk by-products.
• Dry milk solids.
• Nonfat dry milk powder.
Calcium and Vitamin D
Milk and milk products are the most common sources of calcium. Calcium is a mineral
the body needs for strong bones and teeth. If you are lactose intolerant, make sure you
get enough calcium each day.
Other foods contain calcium, such as:
• Canned salmon or sardines with bones.
• Broccoli and other leafy green vegetables.
• Oranges.
• Almonds, Brazil nuts and dried beans.
• Soy milk and tofu.
• Products with added calcium, such as orange juice.
To absorb calcium, your body needs vitamin D. Be sure to
eat foods that contain vitamin D, such as eggs, liver and
certain kinds of fish like salmon and tuna. Sunlight also helps your body make vitamin
D. Vitamin D is added to some milk and milk products. If you’re able to drink small
amounts of milk or eat yogurt, choose varieties that have vitamin D added.
It’s hard to get enough calcium and vitamin D even if you eat and drink milk and milk
products. Talk with your health care provider about how to get calcium and vitamin D in
your diet. Ask if you should also take supplements to get enough calcium, vitamin D or
other nutrients.
Summary
Lactose intolerance means that you cannot digest foods with lactose in them. Lactose
is the sugar found in milk and foods made with milk.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/14/2017
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After eating foods with lactose in them, you may feel sick to your stomach. You may
also have:
• Gas.
• Diarrhea.
• Swelling in your stomach.
Your health care provider may do a blood, breath or stool test to find out if your
problems are due to lactose intolerance.
Lactose intolerance is not serious. Many people with lactose
intolerance can tolerate small amounts of milk - 4 ounces or
less - at a time, especially with meals.
Over-the-counter products are available and may help you
digest milk and milk products.
Milk and foods made with milk are the most common source
of calcium for most people. You may need to take a calcium
supplement if you don't get enough of it from your low-lactose
diet.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/14/2017
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