Gluten: What Is It, Gluten-free Diet, Intolerance, And Sensitivity

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Medical News TodaySubscribeWhat is gluten, which foods have lots, and how to tell if it is an intolerance vs. sensitivity

Medically reviewed by Imashi Fernando, MS, RDN, CDCES — Written by Adda Bjarnadottir, MS, RDN (Ice) — Updated on January 2, 2024

What is gluten?
Issues with gluten
Intolerance vs. sensitivity
Gluten-free diet
FODMAPs
Foods high in gluten
Who should avoid gluten?

Gluten is a protein naturally present in some grains. Most sources claim it is safe for everyone except those with celiac disease. However, some health experts believe that gluten is harmful to most individuals.

According to a 2019 study, up to 5% of people in Western societies report following a gluten-free diet by choice, and up to 13% describe some level of sensitivity to products containing gluten.

This article explains what gluten is and how it can affect a person’s health.

What is gluten?

a person tears open a loaf of bread containing gluten

Gluten is a family of proteins found in grains, including wheat, rye, spelt, and barley.

Of the gluten-containing grains, wheat is by far the most common.

Glutenin and gliadin are the two main proteins in gluten. Gliadin is responsible for most of the adverse health effects of gluten.

When flour mixes with water, the gluten proteins form a sticky network that has a glue-like consistency.

This glue-like property makes the dough elastic and gives bread the ability to rise during baking. It also provides a chewy, satisfying texture.

Interestingly, the name gluten derives from this glue-like property of wet dough.

Gluten intolerance

Most people can tolerate gluten with no adverse effects.

However, it can cause problems for people with certain health conditions.

This includes celiac disease, gluten sensitivity, wheat allergy, and some other diseases.

Celiac disease

Celiac disease, also spelled as coeliac disease, is the most severe form of gluten intolerance. It affects about 1% of the population.

It is an autoimmune disorder in which the body treats gluten as a foreign invader. The immune system attacks the gluten, as well as the lining of the gut.

This damages the gut wall and may cause nutrient deficiencies, anemia, severe digestive issues, and an increased risk of many diseases.

The most common symptoms of celiac disease are:

digestive discomfort
tissue damage in the small intestines
bloating
diarrhea
constipation
headache
tiredness
skin rashes
depression
unexplained weight loss
foul-smelling feces

However, some people with celiac disease may not have digestive symptoms but may have other symptoms, such as tiredness or anemia.

For this reason, doctors often find it challenging to diagnose celiac disease. In fact, in one study, 80% of people with celiac disease did not know they had it.

Non-celiac gluten sensitivity

Many people do not test positive for celiac disease but still react negatively to gluten.

This condition is non-celiac gluten sensitivity.

Researchers do not currently know how many people have this condition, but some estimate it to be in the range of 0.5–13%.

Symptoms of gluten sensitivity include:

diarrhea
stomach pain
tiredness
bloating
depression

There is no clear definition of non-celiac gluten sensitivity. Still, a doctor may make this diagnosis when a person reacts negatively to gluten, but they have ruled out celiac disease and allergies.

However, some experts do not believe that this is a legitimate condition. They think that substances other than gluten cause these adverse effects.

One study looked at 392 people with self-diagnosed gluten intolerance and investigated whether they improved on a gluten-free diet.

The results showed that only 26 people had celiac disease, while two individuals had a wheat allergy. Only 27 of the remaining 364 people received a diagnosis of gluten sensitivity. That means that of all the participants who thought they had gluten intolerance, only 55 people (14%) had gluten issues.

Therefore, many people who think they have gluten intolerance may develop symptoms due to other causes.

Irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common digestive disorder that causes symptoms, including:

abdominal pain
cramping
bloating
gas
diarrhea or constipation, or both

IBS is a chronic condition, but many people can manage their symptoms with diet, lifestyle changes, and stress management techniques.

Research has shown that some individuals with IBS may benefit from a gluten-free diet.

Wheat allergy

For an estimated 0.2–1% of the pediatric population, a wheat allergy may be causing digestive issues after consuming gluten. However, up to 65% find that these issues resolve without treatment as they reach adulthood.

People with a wheat allergy may still consume other foods that contain gluten, such as barley or rye, without experiencing an adverse reaction.

Furthermore, research shows that a gluten-free diet may benefit some individuals with schizophrenia. Other research shows possible benefits for autism and also a disease called gluten ataxia.

Intolerance vs. sensitivity

Digestive discomfort is the most common indication of gluten intolerance. The person may also have anemia or trouble gaining weight.

To determine the cause of the discomfort, people can ask their doctor to check for celiac disease first.

There are two main ways to determine if a person has celiac disease:

Blood tests: Several blood tests screen for antibodies. A common one is the tTG-IgA test. If that is positive, the doctor may recommend a tissue biopsy to confirm the results.
Biopsy from small intestine: A health professional takes a small tissue sample from the small intestine, which a lab analyzes for damage.

A person should undertake both of the above tests while following a gluten-containing diet. Performing the blood test while on a gluten-free diet will yield a false negative. This is because there is no gluten in the system to trigger antibody production.

If a person thinks they may have celiac disease, they should consult their doctor before trying a gluten-free diet.

If the person does not have celiac disease, the best way to find out if they are sensitive to gluten is to follow a strict gluten-free diet for a few weeks to see if symptoms improve.

Then, they will need to introduce gluten back into their diet to see if their symptoms return.

If the person’s symptoms do not improve on a gluten-free diet and do not get worse when they reintroduce gluten, then the cause is probably something other than gluten.

A gluten-free diet test is not a definite way to diagnose the issue, and people should not try this on their own. If a person suspects they may have a problem, they should seek guidance from a healthcare professional who can test for celiac disease or allergies.

Gluten-free diet

Some people may find starting a gluten-free diet rather challenging.

The first thing a person needs to do is read the labels on everything they eat and drink.

Gluten, especially wheat, is an ingredient in a surprising number of foods. Gluten is also present in barley, rye, and any products that contain these ingredients, such as rye bread.

In this diet, people should eat mainly healthy whole foods, as most whole foods are naturally gluten-free. Avoid processed food, cereals, and grains that contain gluten.

Gluten-free grains

Several grains and seeds are naturally gluten free and available to purchase online. These include:

rice
oats
quinoa
flax
millet
sorghum
tapioca
buckwheat
arrowroot
amaranth

However, while oats are naturally gluten free, cross-contamination can occur if a facility processes oats alongside other gluten-containing grains such as wheat. Therefore, it is safest only to consume oats with a gluten-free label.

Gluten-free foods

There are plenty of healthy whole foods that are naturally gluten free, including:

meat
fish and seafood
eggs
dairy products
fruits
vegetables
legumes
nuts
tubers
fats, such as oils and butter

It is generally better for people to choose naturally gluten-free food rather than processed gluten-free products. These tend to be low in nutrients and high in added sugar or refined grains.

Most beverages are also gluten free, except beer unless labeled gluten free.

Various gluten-free recipe books are available to purchase online. Many gluten-free foods are also available online, including gluten-free bread and gluten-free snacks.

Read about which foods are gluten-free here.

FODMAPs

FODMAPs are short-chain carbohydrates found in many foods, including wheat.

Many people cannot digest these properly, which can cause various digestive symptoms.

There is some evidence that people with “gluten sensitivity” may be sensitive to FODMAPs, not gluten.

A 2018 study looked at the effect of fructans, a type of FODMAP, in 59 people who self-reported gluten sensitivity but did not have celiac disease. Researchers found that a fructans diet caused significantly higher gastrointestinal symptoms than gluten consumption. This indicates that FODMAPs may be the culprit for some people who think they react negatively to gluten.

Doctors may recommend that people with IBS follow a low-FODMAP diet. However, many people find this difficult to do, and if a person does not do this correctly, this diet may lead to several nutrient deficiencies. Therefore, people should follow this diet with the help of a healthcare professional.

Foods high in gluten

Sources of gluten in the diet include:

wheat
spelt
rye
barley
bread
pasta
cereals
beer
cakes, cookies, and pastries

Many processed foods may also contain gluten. Anyone who wants to avoid gluten will need to read labels carefully.

Who should avoid gluten?

For many people, avoiding gluten is not necessary.

However, for people with certain health conditions, removing gluten from the diet can make a huge difference.

If people cut out gluten products and do not properly replace them with other carbs in the diet, they could be at risk for inadequate fiber, calories, and B-vitamin intake. A person should always consult with a healthcare professional before trying a gluten-free diet.

People should also make sure to choose healthy foods. A gluten-free label does not automatically mean that a food is healthy, and gluten-free processed food is still processed food.

Summary

Gluten is a group of proteins found in grains. Many popular foods often contain gluten, including bread and pasta.

In recent years, many people have become concerned about consuming gluten and may believe it can cause health problems.

However, research suggests that gluten is safe for most people and that other conditions may cause the symptoms that some may attribute to consuming gluten.

A person should always consult with a healthcare professional before adopting a gluten-free diet.

GastroIntestinal / Gastroenterology
Immune System / Vaccines
Nutrition / Diet
Obesity / Weight Loss / Fitness

How we reviewed this article:

SourcesMedical News Today has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

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Medically reviewed by Imashi Fernando, MS, RDN, CDCES — Written by Adda Bjarnadottir, MS, RDN (Ice) — Updated on January 2, 2024

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