What Is Gluten and What Does It Do?

Gluten, gluten free, gluten intolerance, and coeliac disease are all words we’re becoming more and more familiar with. But let’s get back to basics…what exactly is gluten and what exactly does it do?

What is gluten?

Gluten is a protein that is found naturally in certain grains, including (but not limited to!) wheat. It acts as an adhesive, glueing the protein strands within a grain together. When it is in processed food, it gives structure - either helping to hold a rise, like in bread, or affect the viscosity or thickness of a sauce or soup.

In bread, gluten contributes to the familiar light and slightly springy texture. If you’ve ever seen a bread episode of GBBO, you’ll have heard Paul Hollywood banging on about kneading dough to develop the gluten. Encouraging the protein strands to form longer bonds allows the dough to stretch, so you end up with a more elastic and therefore less crumbly texture. Which is, after all, what we have come to expect from our bread!

What is gluten for?

Gluten is kind of like a building block ingredient because it has this unique ability to provide a stretchy yet stable structure to food. It also contributes to a flavour profile which is familiar and therefore comforting. Now because wheat is so widely available and so useful in food production, it can feel like gluten is everywhere.

Of course, there are the usual suspects (bread, cakes, biscuits), but you might also find gluten in things such as sauces, seasoning packets, processed meats, and imitation meats. Even beer and some wine has gluten in it, usually thanks to barley and barley malt. Barley malt is used as a flavouring in lots of things from malted milk to cereals.

Where does gluten come from?

Most of the gluten we consume comes from wheat-based products, but can also be found in food (and drink!) containing barley, rye, and triticale.

There are also grains that are related to wheat that also contain gluten including, but not limited to, kamut, spelt and farro. 

Millet, quinoa, and oats are some examples of gluten free grains. It is important to note, though, that oats are often produced in the same places that process wheat, barley, and rye, so can become contaminated with gluten.

What does gluten do to your body?

If you are not gluten intolerant at all, gluten will behave the same way as more or less any protein in your body. You’ll chew your food, digest it, absorb the nutrients from the food, and your body will do that magical scientific thing of converting it into energy.

However, if you are gluten intolerant, you may experience adverse symptoms. These can be as relatively benign as some bloating or can be as severe as vomiting and diarrhoea. With coeliac disease, the body will not recognise gluten as food and will attack the body instead, which is why extreme symptoms are experienced.

Who should avoid gluten?

There are three groups of people who should avoid gluten. People who have been diagnosed with coeliac disease, people who have a gluten intolerance, and people who have wheat allergy.

Coeliac disease is an autoimmune condition. With this condition, the body mistakes healthy tissue for bad and attacks it. The medical community does not fully understand why this happens. Nonetheless, for people with coeliac disease, there is something about gluten which causes the immune system to make this error. And this error causes damage to the small intestine. This then makes it harder for the body to absorb nutrients from food. It is thought that genetics and environmental factors also play a role. A coeliac diagnosis involves getting a blood test and, in some cases, a biopsy of the small intestine.

Gluten intolerance (interchangeably called gluten sensitivity) is not an autoimmune condition but can have some symptoms that are similar, and in some cases almost identical, to coeliac disease. But whereas coeliac disease can irreparably damage the small intestine, gluten intolerance cannot. However, at its worst, gluten intolerance can be the culprit for some very uncomfortable and debilitating symptoms. There is currently no test to check for gluten intolerance.

Wheat allergy is different again as it presents more like other food allergies. Skin rash or hives are the most common, but some people also report having nausea, stomach cramps, and indigestion, which sounds more like gluten intolerance, right? Unlike a gluten intolerance, a wheat allergy can be diagnosed with a relatively simple blood test.

Is gluten bad for you?

Gluten is not necessarily bad for you. It is in things that are widely and easily available. Some research even suggests that gluten contributes to healthy gut bacteria. 

However, gluten intolerance is a fairly common complaint - according to Coeliac UK, around 1 in 100 people have coeliac disease and around 10% of the UK population follow a gluten free diet. For people who have coeliac disease or who are gluten intolerant, gluten is not good for you.

How do I know if I'm gluten intolerant?

Chances are if you suspect you are gluten intolerant, you have done some research and found a comprehensive list of symptoms. Below, you’ll find more about the main symptoms.

Unfortunately, as we said earlier, there is not currently a test for gluten intolerance. However, if your GP has reviewed your medical history and symptoms and thinks you might have gluten intolerance, they might recommend something called an elimination diet.

An elimination diet is where you eat as normal for a set amount of time, while your GP carries out tests to rule out certain causes, such as coeliac disease or a wheat allergy. So long as those tests come back negative, your GP will then advise you to eliminate the suspected irritant (gluten, in our case) for another amount of time. If in that time, your symptoms get better, then gluten (or other irritant) is slowly incorporated back into your diet. If the symptoms then come back, your GP will likely conclude you are gluten intolerant.

It is important that this process is carried out under the eye of a medical professional in order to rule out other possible issues.

What are the most common symptoms of gluten intolerance?

Gluten intolerance has a very wide breadth of symptoms. And of course how serious those symptoms vary hugely as well. Some symptoms seem to make sense anatomically but some are more surprising. A person might experience only a couple of symptoms or many - it is a bit of a nasty pick and mix, to be honest!


Bloating is the uncomfortable feeling of being overfull. It can be caused by lots of things (eating too fast or being on your period) and can be very uncomfortable. Occasional bloating isn’t necessarily anything to worry about, but you may have an underlying condition if you experience bloating frequently.

Diarrhoea, constipation, smelly faeces

Most people occasionally experience diarrhoea and constipation. However, people with coeliac disease will find that after they eat gluten, their small intestine becomes inflamed. This leads to frequent bouts of diarrhoea and because nutrient absorption is poor, the faeces can be particularly smelly.

Headaches and migraines

Again, most of us get the occasional headache, whether from not drinking enough water or the everyday stress of life. People who are gluten intolerant might find that gluten gives them a headache. Some research has shown that people who are gluten intolerant are more susceptible to migraine episodes.

Feeling tired and Brain fog

Feeling tired is so common. But it usually isn’t linked to any one condition. And there’s a difference between feeling generally a bit tired and constant fatigue. Constant fatigue coupled with brain fog (being unable to think with clarity) could suggest an underlying condition, one of which could be gluten sensitivity.

Skin problems

Surprisingly, skin is another thing that can be affected by gluten. Around 10 percent of people who have coeliac disease, may have a blistering skin condition called dermatitis herpetiformis. Research has also shown that a gluten free diet can help skin problems such as psoriasis (an inflammatory condition with scaling) and alopecia areata (non-scarring hair loss).

Depression and Anxiety

There is some research to suggest that people who have digestive issues are more likely to suffer from depression and anxiety. It seems to be particularly common for people with coeliac disease, though there does not seem to be a single reason why.

Depression is usually characterised by feelings of hopelessness and sadness - according to the Office of National Statistics, around 1 in 6 adults in the UK experienced depressive symptoms in 2022. If this rings true for you, gluten related or not, please speak to your GP.

Iron deficiency anaemia

Iron deficiency anaemia is a fairly common condition and again has a variety of causes, such as heavy periods or pregnancy. Coeliac disease damages the small intestine’s ability to absorb nutrients, which means less iron absorption. Iron is quite complicated to absorb anyway (it has to do with needing vitamin C, but not needing calcium for your body to absorb it), so people with coeliac disease have it doubly difficult. 

Joint and muscle pain

Another surprising symptom can be joint and muscle pain. For people with gluten sensitivity, eating gluten can cause an inflammatory reaction which manifests in pain in muscles and joints. For people with coeliac disease, this tends to show up as a tingling or numbness in hands and feet, called peripheral neuropathy. Of course, it is definitely worth remembering that joint and muscle pain have many causes.

If you think you might have coeliac disease, Coeliac UK have a useful tool here www.isitcoeliacdisease.org.uk.

Keep in mind that this list is not exhaustive, more information can be found via the NHS and Coeliac UK.

Can I suddenly become gluten intolerant?

In a word, yes, you can suddenly become gluten intolerant. Anecdotally, some people have become gluten intolerant later in life, sometimes after a stressful life event, surgery, or even just taking antibiotics. There is some thought that ageing plays a part in changes to our digestive system. Simply put, as we age, our bodies are just less efficient, which can manifest in a myriad of ways.

Coeliac disease is a little different. One research study followed up with people who previously tested negative for coeliac disease only to be diagnosed with it later in life. It is not yet known why exactly this is the case. It is also worth noting that while many children outgrow allergies to things like eggs and cow’s milk, coeliac disease is a lifelong condition. According to Coeliac UK, most people diagnosed with coeliac disease are 40-60 years old.

Does gluten cause weight gain?

Gluten itself does not cause weight gain. The trouble is what gluten is found in, which tends to be processed and ultra-processed foods. Processed foods tend to be higher in sodium and higher in sugar. High sodium has been linked to high blood pressure and we all now know that we should be watching our sugar intake.

Ignored intolerance to gluten actually is more likely to make you lose weight because your small intestine stops working properly so you cannot effectively absorb nutrients from food. However, according to Coeliac UK, research suggests that most people who have coeliac disease are of normal weight or overweight at the time of diagnosis.

Even if you lived on a diet of cakes, processed bread, and gravy, the gluten itself would not cause you to gain weight.

How can I test for gluten intolerance at home?

The NHS does not recommend any home test that claims to diagnose food intolerance. And there is no test that can accurately detect gluten intolerance. If your symptoms are persistent or if you are closely related to someone who has coeliac disease, it is important to speak to your GP who advise you further.

Even if you do not suspect you have coeliac disease and are experiencing symptoms after eating gluten, please speak to your GP for professional and specific medical advice.

How soon after eating gluten do symptoms appear?

Bodies are different. And each of our bodies reacts in different ways. So for some people, symptoms can flare up within just minutes of eating gluten and in others, it can even take days.

For some people, the amount of gluten may affect how quickly symptoms can appear. Those who are gluten intolerant might be able to have some amount of gluten and only have mild symptoms. People with coeliac disease are more likely to have a reaction to only a few crumbs.

You may have seen that for something to be labelled gluten free it has to test as 20 parts per million or less. You might also see it as 20ppm/kg. Is that a few crumbs? No. It is far, far, far smaller. Thankfully, the maths and research has been done for us, and according to Coeliac UK, 20ppm or less has been shown to be safe for people with coeliac disease.

How do I avoid gluten?

When you start looking for it, gluten seems to be everywhere and in everything. Whether you need to be vigilant about your gluten intake or you are curious to try gluten free eating, the best thing you can do is start to read the ingredients or opt for foods that are labelled gluten free.

A great place to start is the fruit and veg aisle, which is happily entirely gluten free. Another one is meat and fish - so long as you’re buying it free of a marinade and breading, you should be good to go. And another wonderful thing to look for is things like pasta made from alternative ingredients. For example, our pasta is made from 100% yellow peas, nothing else.

Does gluten make you tired?

Lethargy, or chronic tiredness, can definitely be a symptom experienced by people who are gluten intolerant. This is sometimes called gluten fatigue and is more like a fog that doesn’t lift after sleeping.

But wait, who hasn’t felt tired after they’ve smashed an entire Friday night pizza with garlic bread on the side? Ah, see, that’s not gluten’s fault. That probably has to do more with the balance of simple and complex carbohydrates. Research has shown that after eating simple carbohydrates (like pizza) we experience a high followed by a crash. When we opt for a complex, slow-release carbohydrate (like our 100% yellow pea pasta), we’re more likely to experience sustained energy.

Does gluten make you bloated?

Bloating after you eat gluten can be one of the first signs of gluten intolerance. But what exactly is bloating? In a nutshell, bloating is the feeling of your stomach feeling too full. A variety of things can contribute to bloating, but essentially it is what you eat and how you eat.

Those who are gluten intolerant will find that gluten can make them bloated, as excess gas builds up in the stomach. You might have seen the term “gluten belly” thrown out there, which is a catchy term for the feeling of bloating, sometimes including feeling sick or tired.

Some people also find that some vegetables, fizzy drinks, and even eating fast make them feel bloated. The good news is that if you aren’t sensitive to gluten, gluten itself will not make you feel bloated.

Does gluten affect sleep?

For most people, gluten will not affect their sleep either positively or negatively. However, for those with coeliac disease, insomnia and sleep apnea can be a problem.

Even if you have gluten sensitivity, other symptoms can affect how you sleep. For example, if you are feeling uncomfortable with bloating when you are trying to get to sleep, it can be harder to get to sleep in the first place.

Final thoughts

Gluten is one of those amazing molecules that allow our food to do pretty excellent things. But it can also be really harmful to some people.

If you are happily living your life eating gluten, you do you, gluten itself will not harm you. But the more we learn, the more aware we can be! So maybe be a little more mindful of your friend who can’t enjoy gluten (and keep a box of our pasta in your cupboard for when they come round - buy it here).

If you suspect you may have coeliac disease, please speak to your GP. It is essential to not make any changes to your diet until you have a diagnosis, as you may not get an accurate test result.

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