What is gluten intolerance?

A person with gluten intolerance or sensitivity may experience pain and bloating after eating foods that contain gluten. Gluten is a protein in cereals such as wheat, barley, and rye.
Research indicates that around 1% of people in the United States have celiac disease, 1% have a wheat allergy, and 6% or more have gluten intolerance — also known as non-celiac gluten sensitivity.
around 1%
celiac disease
wheat allergy
gluten intolerance
non-celiac gluten sensitivity
What is gluten intolerance?

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Gluten intolerance can cause similar symptoms to celiac disease, but it is a different issue with different long-term effects.
The symptoms of gluten intolerance may also resemble those of a wheat allergy or intestinal conditions such as irritable bowel syndrome (IBS). Experts estimate that 10–15% of adults in the U.S. have IBS symptoms.
irritable bowel syndrome
10–15%
People with celiac disease must avoid gluten, as it can cause intestinal damage and prevent the body from absorbing essential nutrients.
intestinal damage
Those with a wheat allergy must avoid all wheat products, as consuming any could be immediately life threatening.
Gluten intolerance can lead to discomfort, but it is unlikely to cause severe symptoms that require emergency care.
Gluten intolerance
Scientists have found evidence that environmental factors can play a role in celiac disease.
environmental factors
celiac disease
However, experts are unsure of exactly what causes gluten intolerance and how it relates to similar illnesses. Some researchers have suggested that other ingredients in wheat, not gluten, may be causing some of these reactions.
unsure
how it relates
researchers
Symptoms
An individual with gluten intolerance will develop symptoms after consuming foods containing wheat, barley, or rye.
The symptoms may include:
include
tiredness
tiredness
bloating
abdominal pain
diarrhea
diarrhea
nausea
constipation
constipation
a general feeling of being unwell
The following may also occur:
anxiety
anxiety
headaches
headaches
brain fog
confusion
numbness
joint or muscle pain
a skin rash
See a doctor about any of the above symptoms. A correct diagnosis is important — many conditions affecting the gut have similar symptoms.
Severe abdominal pain can be a symptom of a serious medical issue, and anyone who experiences it should receive immediate medical attention.
For more science-backed resources on nutrition, visit our dedicated hub.
dedicated hub
Gluten intolerance vs. wheat allergy
When a person has a wheat allergy, their body reacts to a protein in wheat, and this protein is not necessarily gluten.
A wheat allergy can cause life-threatening symptoms. Anyone with this allergy who ingests wheat requires immediate medical attention.
wheat allergy
A person with a wheat allergy may develop:
hives
hives
swelling
breathing difficulties, including wheezing
In severe cases, anaphylaxis may develop. This serious reaction causes the body’s blood pressure to fall, and the person may lose consciousness and stop breathing.
anaphylaxis
blood pressure
While an allergic reaction requires urgent care, an intolerance is not immediately dangerous. However, it can cause discomfort and may affect a person’s overall health.
Anyone who believes that they may have either an intolerance or an allergy should consult a doctor.
Learn more about a wheat allergy here.
here
In this article, we describe additional differences between a food allergy and an intolerance.
In this article, we describe additional differences between a food allergy and an intolerance.
Foods to avoid
Glutens are proteins that enable wheat and other cereals to absorb water, stick together, and remain viscous and elastic. They help give bread dough its texture and make it possible for the dough to rise, for example.
Wheat, barley, and rye contain gluten, which may be present in:
breads
cookies and biscuits
pastas
semolina-based products
couscous
some beers
Gluten may also be in products that are not obviously cereal-based, such as:
seasonings
sauces
soups
canned foods
spices
What foods can I eat?
Foods that do not contain gluten include:
fruits and vegetables
plain meat, poultry, and fish products
pulses, such as beans and lentils
rice
quinoa
quinoa
potatoes
some oat products
A person looking to avoid gluten should be sure to check food labels carefully. It may also be a good idea to make soups, sauces, and salad dressings at home.
Products with “gluten-free” on their labels do not contain enough gluten to trigger symptoms of celiac disease or gluten intolerance. Manufacturers may remove the gluten from wheat flour or use a substitute, such as oat or chickpea flour.
Here, learn more about what a gluten free diet includes.
Here
Find out more about alternatives to wheat bread in this article.
in this article
Many fast foods contain gluten, but some major chains are now offering gluten-free options. Learn more about gluten-free fast food here.
here
Diagnosis
If a person believes that consuming gluten is causing any health issues, they should see a doctor.
After asking about symptoms and carrying out a physical exam, the doctor will likely perform laboratory tests to rule out celiac disease and other gastrointestinal conditions. They may then recommend a plan that allows them to monitor the person’s diet any ill effects.
Researchers have yet to find any specific biomarker of a gluten intolerance. At present, before diagnosing gluten intolerance, the doctor will need to rule out other options.
It can be challenging to differentiate between celiac disease and gluten intolerance, but testing for antibodies can help.
testing for antibodies
To rule out or diagnose celiac disease, a doctor may ask for:
Blood tests: If results show that certain antibodies are present, the person may have celiac disease.
A biopsy: This involves taking a tissue sample from the lining of the intestine. If results show damage to the lining, the person may have celiac disease.
If the doctor rules out celiac disease, they may look for signs of IBS or wheat or gluten intolerance next.
One group of researchers has suggested the following plan, which a person follows at home but under medical supervision:
researchers
The individual specifies 1–3 symptoms to monitor.
They consume a diet containing gluten for 1 week.
They avoid gluten completely for the next week.
They reintroduce some gluten in cooked foods for another week.
They monitor for any symptoms and report back to their doctor.
The researchers who proposed this plan believe that it could help with a definitive diagnosis.
If a person has concerns about gluten in their diet, they should see a doctor before making any dietary changes. Doing so will help the doctor make a correct diagnosis.
see a doctor
Experts emphasize the need for tests that can identify gluten intolerance and distinguish it from celiac disease, IBS, and other intestinal conditions. Such tests would enable doctors to provide more effective treatment for each issue.
Experts
Living with gluten intolerance
A person with gluten intolerance should eliminate gluten from their diet. However, consuming gluten occasionally is unlikely to cause severe health problems, unless a person has celiac disease.
Keeping a record of meals and symptoms can help a person identify potentially problematic foods, and it may also help them manage an intolerance.
Takeaway
Some people experience adverse reactions to wheat and other cereals. They may have an intolerance to gluten or another component.
Some experts have expressed concern that people who avoid gluten are missing out on essential nutrients in whole grains. Grains can also be a crucial source of energy.
experts
Anyone who is considering going gluten-free should consult a doctor or dietitian about the necessity and strategies for doing so a healthful way.
Who should follow a gluten-free diet? Find out here.
here
If I have gluten intolerance, does this mean that I am more likely to have symptoms if I eat a lot of gluten? In other words, if I eat a little, should I be OK?

Those with gluten intolerance often have a threshold of tolerance — there is usually an amount of intake that you can consume before experiencing symptoms.
The challenge is that this threshold varies from person to person. One person might be able to tolerate 1 serving a day (equivalent to 1 slice of bread), whereas someone else may not be able to tolerate more than half a serving.
Typically, yes: If you have an intolerance to gluten, the more gluten you eat, the higher the risk of symptoms.

Natalie Butler, R.D., L.D. Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.