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Knowledge Base » Food Hygiene » What is Gluten?

What is Gluten?

Last updated on 20th December 2023

It is estimated that 8.5 million people in the UK have now gone “gluten free”. In the supermarket there is an ever expanding, and often quite expensive, range of gluten-free alternative foods on sale and it is one of the fastest-growing dietary sectors in food retailing.

There are also a growing number of “gluten free” cafés, restaurants and pubs emerging throughout the country to cater for an increasing number of people following a gluten-free diet for allergen, health or other reasons. But what is gluten?

Gluten is a gluey, chewy dietary protein found in three types of cereal:

  • Wheat.
  • Barley.
  • Rye.

The average daily gluten intake in a Western diet is thought to be 5–20 grams per day. Gluten-containing grains are important staple foods, for example gluten gives dough its elasticity, acting like a glue, and gives bread its classic chewy, soft texture.

It is also commonly used as an additive in processed foods for improved texture, moisture retention and flavour. Gluten can be found in all products and by-products of wheat, barley and rye grains, and some oat products.

Barley Rice Containing Gluten

What foods contain gluten?

Wheat products including:

  • Breads and bakery items such as croissants, pita, naan, bagels, flatbreads, cornbread, potato bread, muffins, donuts, rolls, cakes, biscuits, pie crusts, brownies, tortillas, even cheesecake filling, as some recipes include wheat flour.
  • Pastas such as raviolis, dumplings, couscous and gnocchi.
  • Noodles such as egg noodles.
  • Breakfast cereals.
  • Sauces such as traditional soy sauce, cream sauces made with a roux, bread sauces and stuffing, salad dressings.
  • Certain sweets such as energy bars.
  • Soups – pay special attention to cream-based soups which have flour as a thickener.

All varieties of wheat contain gluten, including durum, semolina, spelt, kamut, einkorn, faro and triticale. (Triticale is a hybrid of wheat and rye.)

Barley products including:

  • Soups – many soups contain barley.
  • Beer unless explicitly gluten-free.
  • Whiskey (or whisky).
  • Malt.
  • Rich Tea biscuits.
  • Malted milk, Horlicks, Ovaltine and milkshakes.
  • Brewer’s yeast.
  • Yeast extract including spreads such as Marmite.
  • Cereals – corn flakes and puffed rice often contain malt extract/flavouring.

Rye products including:

  • Certain breads, for example pumpernickel.
  • Cereals.
  • Beer unless explicitly gluten-free.
  • Rye flour.
  • Rye milk.
  • Any products containing triticale, a hybrid of wheat and rye.

Be aware that oats may contain traces of gluten too, as cross-contact may occur when oats are grown side-by-side with wheat, barley or rye. As oats are often used as an alternative in a gluten-free diet, only use oats that are labelled gluten-free and note that granola, another alternative food, is often made with regular oats, not gluten-free oats.

People ask if whisky (whiskey) is gluten free? According to Coeliac UK, “Even when a cereal that contains gluten is used as an ingredient, all spirits are distilled during the manufacturing process and this process removes any trace of gluten. Therefore, all spirit drinks (including malt whisky which is made from barley) are safe for people with coeliac disease.”

However, be on the lookout for hidden gluten in whiskies (whiskeys) that add flavourings or other additives after distillation. There is also a risk for gluten cross-contact in facilities that process other products containing wheat, barley, or rye.

Gluten is found in a wide variety of foods, even those you would not expect, such as:

  • Soy sauce.
  • Potato crisps – some potato crisp seasonings may contain malt vinegar or wheat starch.
  • Veggie burgers, sausages and bacon may be made with seitan (wheat gluten).
  • Some French fries and chips.

It is more obvious that foods containing wheat, barley or rye contain gluten, but the protein can also be hidden in many foods as an additive, especially in processed foods.

Traces of gluten can also sometimes be found in a variety of items you might never realise, such as:

  • Prescription or over-the-counter medications.
  • Vitamins and supplements.
  • Lipstick, lip-gloss and lip balm.
  • Play dough – children may touch their mouths or eat after handling wheat-based play dough.
  • Communion wafers.

Therefore, the advice is to learn to read manufacturers’ labels, not only on food, and talk to café, restaurant and pub owners about their produce and allergen safety measures.

What is gluten intolerance?

Over half a million people in the UK, 1% of the population, suffer from coeliac disease and possibly there are still over half a million people with undiagnosed coeliac disease. Coeliac disease is a serious autoimmune disease that occurs in genetically predisposed people where your immune system attacks your own tissues when you eat gluten. The ingestion of gluten leads to damage in the small intestine.

Coeliac disease is hereditary, meaning that it runs in families. People with a first-degree relative with coeliac disease (parent, child or sibling) have a 1 in 10 risk of developing coeliac disease.

It can develop at any age after people start eating foods or taking medicines that contain gluten. Although symptoms are most likely to develop during early childhood, between 8 and 12 months old, it may take several years before a correct diagnosis is made, or it may not develop until later in adulthood between 40 and 60 years of age.

Symptoms of Coeliac Disease

Eating foods that contain gluten can trigger a range of gut symptoms, such as:

  • Diarrhoea.
  • Stomach aches.
  • Bloating and flatulence.
  • Indigestion.
  • Constipation.

Coeliac disease can also cause more general symptoms, including:

  • Tiredness and fatigue as a result of not getting enough nutrients from food and suffering malnutrition.
  • Unintentional weight loss.
  • An itchy rash (dermatitis herpetiformis).
  • Problems getting pregnant (infertility).
  • Nerve damage (peripheral neuropathy).
  • Disorders that affect co-ordination, balance and speech (ataxia).
  • Children with coeliac disease may not grow at the expected rate and may have delayed puberty.

Routine testing for coeliac disease is not done in England and testing is usually only recommended for people who have an increased risk of developing coeliac disease, such as those with a family history of the condition.

If you are a first-degree relative of anyone with coeliac disease, you should be tested if you are experiencing any of the above symptoms. Speak to your GP or NHS 111 to find out whether you are at risk of developing coeliac disease or whether there is another reason for your symptoms.

Testing for coeliac disease involves having:

  • Blood tests – To detect antibodies usually present in the bloodstream of people with coeliac disease. If coeliac disease antibodies are found in your blood, your GP will refer you for a biopsy of your gut. However, it’s sometimes possible to have coeliac disease and not have these antibodies in your blood. If you continue to have coeliac disease-like symptoms despite having a negative blood test, your GP may still recommend you have a biopsy.
  • A biopsy – To confirm the diagnosis. A biopsy is carried out in hospital, usually by a gastroenterologist. The gastroenterologist will pass a tiny biopsy tool through an endoscope to take samples of the lining of your small intestine. The sample will then be examined under a microscope for signs of coeliac disease.

While being tested for coeliac disease, you will need to eat foods containing gluten to ensure the tests are accurate. You should also not start a gluten-free diet until the diagnosis is confirmed by a specialist, even if the results of blood tests are positive. If you are diagnosed with coeliac disease, you may also have other tests to assess how the condition has affected you so far.

There is no cure for coeliac disease, but following a gluten-free diet should help control symptoms and prevent the long-term complications of the condition. If you have coeliac disease, you must give up all sources of gluten for life. Your symptoms will return if you eat foods containing gluten, and it will cause long-term damage to your health.

Left untreated, coeliac disease can lead to additional serious health problems such as coronary artery disease, bowel cancers and other autoimmune disorders like type 1 diabetes, multiple sclerosis (MS), and conditions including anaemia and osteoporosis. It is not entirely clear what causes the immune system to act this way against gluten, however, research shows that a combination of genetics and the environment appear to play a part.

Gluten Intolerant

Non-coeliac gluten sensitivity

There is a far higher number of people, various estimates put this at between 6% and 8% of the population, some 3 million people, who self-select a gluten-free diet. These people are now classified as having non-coeliac gluten sensitivity. This is a new area and needs more research to understand the condition and who is at risk.

The overall prevalence of non-coeliac gluten sensitivity in the general population is unknown, largely due to the fact that many people self-diagnose and start a gluten-free diet of their own accord, without consulting a medical professional. You should always consult a medical professional if you suspect something is up.

Non-coeliac gluten sensitivity causes some signs and symptoms associated with coeliac disease including:

  • Abdominal pain.
  • Bloating.
  • Diarrhoea.
  • Constipation.
  • “Foggy brain”.
  • Rash.
  • Headaches.

Differences of non-coeliac gluten sensitivity in comparison to coeliac disease

Although both conditions have similar symptoms and are therefore easily confused, there are differences, for example in terms of reaction times and the manner of the development of the disease.

Coeliac disease is an autoimmune disease of the intestine caused by gluten, whereas although people with non-coeliac gluten sensitivity develop symptoms similar to those observed in coeliac disease after eating food containing gluten, the clinical picture is generally less severe and it is not possible to detect auto-antibodies or any of the associated diseases.

In contrast to coeliac disease, people with non-coeliac gluten sensitivity show little or no change to their small intestine’s cells and tissue.

Even though there is no damage to the tissues of the small intestine, some studies show that the immune system plays a role, but the process is not well understood. There are no specific diagnostic tests as non-coeliac gluten sensitivity has been historically harder to diagnose than coeliac disease; it does not fit the same criteria. If you are experiencing any of the above symptoms speak to your GP or NHS 111.

Gluten-free diet

Keeping a strict gluten-free diet is a lifelong necessity for people with coeliac disease. Following the diet and avoiding cross-contamination results in fewer symptoms and complications of the disease. For some people with non-coeliac gluten sensitivity, the condition may not be lifelong.

Some research suggests that you may follow a gluten-free diet for a certain period, for example one or two years, and then retest your sensitivity to gluten to find that you are now tolerant. For other people with non-coeliac gluten sensitivity, the diet may be a lifelong treatment.

For those who are following a gluten-free diet, the following foods naturally do not contain gluten:

  • Most dairy products, such as cheese, butter and milk.
  • Fruit and vegetables.
  • Meat and fish (although not breaded or battered meat and fish).
  • Potatoes.
  • Rice and rice noodles.
  • Lentils.
  • Gluten-free flours, including rice, corn, soy and potato.

Grains, starches or flours that can be part of a gluten-free diet include:

  • Amaranth.
  • Arrowroot.
  • Buckwheat.
  • Corn, cornmeal and polenta labelled gluten-free.
  • Flax.
  • Gluten-free flours such as rice, soy, corn, potato and bean flours.
  • Hominy (corn).
  • Millet.
  • Quinoa.
  • Rice, including wild rice.
  • Sorghum.
  • Soy.
  • Tapioca (cassava root).
  • Teff.

By UK law, food labelled as gluten free can contain no more than 20 parts per million (ppm) of gluten.

The foods not included in a gluten-free diet provide important vitamins and other nutrients, for example, whole-grain breads and other products are natural or enriched sources of the following:

  • Iron.
  • Calcium.
  • Fibre.
  • Thiamine.
  • Riboflavin.
  • Niacin.
  • Folate.

Therefore, following a gluten-free diet will likely change your nutrient intake. Some gluten-free breads and cereals have significantly varied nutrient levels compared with the products they are replacing. Some gluten-free foods also have higher fat and sugar contents than the gluten-containing food being replaced.

It is important to read labels, not only for gluten content but also for overall nutrient levels, salt, calories from fats and calories from sugars. If you are following a gluten-free diet you should talk to your GP or a dietitian about foods that would provide you with healthy, nutrient-rich alternatives.

Following a gluten-free diet is a learning process, not only for you but also for your family and friends. Mistakes can happen, especially if you have only recently been diagnosed. If you make the occasional mistake and eat gluten by accident, it is unlikely to cause lasting gut damage.

The effects vary from person to person and depend on how much gluten you have eaten, how sensitive you are and how long you have been on a gluten-free diet. If you are concerned then check with your pharmacist, dietician or GP.

Being Tested For Coeliac Disease


There are plenty of alcoholic and soft drinks which do not contain gluten such as:

  • Fruit juice.
  • Flavoured water.
  • Fizzy drinks.
  • Cider.
  • Wine.
  • Sherry.
  • Spirits, with the exception of whiskey (or whisky).
  • Port.
  • Liqueurs.

There are also specially made gluten-free beers and lagers available.

Food preparation and eating out

For people with coeliac disease, in particular, it is important to avoid exposure to gluten. The following tips can help you prevent cross-contamination in your own food preparations at home and avoid gluten-containing food when you eat out:

  • Store gluten-free and gluten-containing foods in separate places.
  • Keep cooking surfaces and food storage areas clean.
  • Wash dishes, cutlery and cooking equipment thoroughly.
  • Toast bread in the oven or consider separate toasters to avoid cross-contamination.
  • Read café, restaurant and pub menus online ahead of time, if possible, to be sure there are options for you, or contact the café, restaurant or pub to discuss your dietary needs.
  • If you order a “special gluten-free” meal, check that your instructions were followed.
  • If you are going to someone else’s house for a get-together and are unsure of the menu, bring along a dish or two that you are sure you can eat. That way you are not left hungry.
  • If you are not sure if there will be something you can drink, bring along a bottle or two of something you can drink.
  • The most important rule to follow is, when in doubt, don’t eat it.

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About the author

Megan Huziej

Megan Huziej

Megan has worked with CPD Online College since August 2020, she is in charge of content production, as well as planning, managing and delegating tasks. Megan works closely with our writers, voice artists, companies and individuals to create the most appropriate and relevant content as well as also using and managing SEO. She gained her Business Administration Level 3 qualification over the duration of being at CPD Online College as well. Outside of work Megan loves to venture to different places and eateries as well as spending quality time with friends and family.

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