Gluten is one of the most controversial components of modern nutrition. People often associate it with negative effects such as weight gain, digestive issues, or difficulty concentrating. You can even read about these concerns in popular science books like Grain Brain or Wheat Belly. But is gluten really as harmful as it’s made out to be, or is it just another scapegoat in the world of modern diets? Let’s take a closer look at current research on gluten and its impact on human health.
What Is Gluten?
Many people think gluten is just one thing, but that’s not entirely true. It’s actually a general term for a group of plant-based glycoproteins known as prolamins. These naturally occur in cereal grains and play a role in the plant’s growth and germination. Gluten is found not just in wheat, where it gets the most attention, but in other grains as well. Each grain contains a specific prolamin with a different name, though they have similar properties. [1]
Types of Gluten in Grains
- Gliadin and glutenin in wheat
- Hordein in barley
- Secalin in rye
- Avenin in oats
Prolamins, or gluten, are particularly well-known to bakers. When mixed with water, gluten forms an elastic network in flour, giving dough its stretchiness and ability to rise. Without gluten, pizza dough wouldn’t be able to stretch above a pizza maker’s head without tearing apart. Besides pizza, gluten is essential for making traditional bread, pasta, cakes, and other baked goods, as it provides elasticity and a soft, airy texture. Each type of gluten has slightly different properties, which is why there’s a difference between wheat bread and rye bread. [2]
In this article, we’ll mainly focus on the gluten found in wheat, barley, and rye. Oats are a bit more tricky—many people with coeliac disease can tolerate oats, but there’s a risk of contamination with other gluten-containing grains during production. A safer alternative is certified gluten-free oats, which contain no more than 20 mg of gluten per kilogram.
Where in the Grain Is Gluten Found?
Most of us have probably seen a wheat grain before. It’s processed through milling and other methods to produce flour of varying coarseness, which can then be used to bake bread and other baked goods. Different parts of the grain have different properties, which influence the final product.
- Endosperm (core): The largest part of the grain, containing starches (carbohydrates) and proteins. It’s the main energy source and forms the basis for white flour production.
- Gluten: The protein found in the endosperm, made up of gliadin and glutenin, which give dough its elasticity and soft, airy texture.
- Bran: The outer layer of the grain, rich in fibre, vitamins, and minerals. It’s removed during white flour production but retained in wholegrain flour.
- Germ: The innermost part of the grain, which contains fats, vitamins, and minerals.
Are Gluten-containing Foods New to Our Diet?
Gluten and the grains that contain it have been a staple of human diets for thousands of years. Around 10,000 BCE, humanity began shifting from hunting and gathering to growing grains similar to modern wheat. For our ancestors, grains provided a stable food source that accelerated the development of civilisation. They learned how to mill grains into flour, which they could store and use to make various flatbreads. Over time, they also discovered gluten’s ability to trap air bubbles, a key factor in dough rising. This discovery led to the development of baking techniques we still use today.
Foods Containing Gluten
| Wheat | Bread, pasta, cakes, biscuits | Contains the largest amount of gluten |
| Spelt (farro) | Bread, pasta, cakes, biscuits | A type of wheat |
| Kamut (khorasan) | Side dish, patties | A type of wheat |
| Barley | Beer, malt, cereals | |
| Rye | Bread, biscuits | |
| Triticale | Bread mixes, animal feed | A cross between wheat and rye |
| Oats | Oatmeal, muesli | Naturally gluten-free but can be contaminated during production |
| Couscous, bulgur | Salads, side dishes | Made from wheat |
| Seitan | Plant-based meat alternative | Pure wheat gluten |
Does Modern Wheat Contain More Gluten?
There’s a common belief that modern wheat contains more gluten than the varieties grown by our ancestors, and some people blame this for the rise in gluten-related digestive problems. However, studies show that the gluten content hasn’t changed dramatically over the past 120 years. While we don’t know for sure what’s behind the increased sensitivity to gluten, it’s likely a combination of changes in how grains are processed, dietary habits (with more highly processed foods in our diets), and lifestyle factors. Greater awareness and more accurate diagnoses of gluten-related conditions may also play a role. [3]
How Is Gluten Digested?
You may have heard someone claim that gluten “sticks” to the intestines, which is why they’ve decided to cut it out entirely. While the name might lend itself to that idea, fortunately, the human digestive system can handle gluten just fine. Healthy individuals have enzymes that can almost completely break down gluten into simpler, more digestible components. This process starts with the enzyme pepsin in the stomach and continues with pancreatic enzymes (proteases) in the small intestine. The result is simple amino acids that enter the bloodstream and are used by the body where needed. One component of gluten, gliadin, can’t be fully broken down. It remains in the small intestine and is eventually excreted. For healthy individuals, this isn’t a problem, but for those with coeliac disease or non-coeliac gluten sensitivity, undigested gliadin can lead to digestive issues. [4]
Is Gluten Harmful?
In recent years, gluten has earned a reputation as one of the biggest dietary “villains,” alongside white sugar and butter. In some parts of the world, such as Hollywood, gluten fears have become so widespread that you could probably rob a bank with a bread roll in hand. But is it really necessary to give up crusty bread, pizza, and other delicious foods just because it’s trendy? The truth is, gluten isn’t harmful at all for most people and poses no dietary risk.
However, the situation is different for those diagnosed with coeliac disease, non-coeliac gluten sensitivity, or a wheat allergy. In these cases, gluten causes health problems, and cutting it out of the diet is essential. For everyone else, it’s a natural and safe part of their diet.
Why Do Healthy People Follow a Gluten-Free Diet?
Why have so many people started cutting gluten from their diets? As with many trends, it often starts with a few celebrities. Some have promoted gluten-free eating as a way to lose weight and feel better, sparking the rise of a new nutritional holy grail.
It’s true that you can lose weight on a gluten-free diet, but it’s usually not due to eliminating gluten itself. Instead, it’s often because of changes in eating habits. When you cut out bread, pasta, and other gluten-containing foods without replacing them, you’re likely to reduce your calorie intake. At the same time, you might stop eating croissants, cheese straws, and other ultra-processed foods. If you start eating more fresh fruits and vegetables instead, you’ll probably find yourself losing weight. However, this is due to the calorie deficit you’ve created through dietary changes, not the absence of gluten.
If you’d like to know more about losing weight on a gluten-free diet, read our article Is Weight Loss on a Gluten-Free Diet Really Quick and Sustainable?
Does Gluten Cause Weight Gain and Obesity?
People often search for a single culprit to blame for their extra weight, and you may have come across claims online or in women’s magazines suggesting that gluten causes fat accumulation, especially around the belly. This phenomenon even has a name—”wheat belly.” Supporters of this theory often cite animal studies. In some cases, they claim that peptides formed during gluten digestion in the intestines slow down metabolism, which then leads to weight gain. However, studies on humans have not confirmed this. In fact, no correlation between gluten consumption and weight gain, or body weight and BMI, has been found to this day. Furthermore, whole grain foods, which contain gluten, are recommended by global health authorities as part of a healthy and balanced diet that helps maintain an optimal weight. [17]
Gluten critics often point to a 2013 study conducted on mice, where it was found that mice fed gluten gained about 20% more weight compared to rodents on a gluten-free diet with the same calorie intake. While these results are interesting, they come with limitations. It’s difficult to compare the digestive function and metabolism of humans and mice. Moreover, the gluten doses used in the study were equivalent to eating about 20 slices of bread daily, which is far more than most people typically consume. So far, the relationship between gluten and human weight remains a mystery. Generally, when trying to lose weight, focusing on the overall composition of your diet is more effective than fixating on one component. [5]
If you’re interested in how to lose weight healthily and sustainably, read our article 10 Tips to Make Losing Weight Easier and Get in Shape.
Does Gluten Cause All Digestive Problems?
Gluten often gets blamed for a wide range of digestive issues. In some cases, this blame is justified, and the only solution is to eliminate it from the diet for life. However, this applies only after a confirmed diagnosis of coeliac disease or another condition where gluten has been proven to have a negative effect. Symptoms like stomach pain, bloating, and other digestive troubles may be caused by entirely different factors—such as excessive intake of fat, fibre, or lactose intolerance. These problems can also occur when you eat fresh, warm bread. It’s hard to resist, but that perfect taste experience is often followed by stomach discomfort and bloating, which feels like it could launch you into space. Freshly baked bread contains more warm steam and moisture, which may cause these symptoms in sensitive individuals. [6–7, 18]
To learn more about common causes of bloating and other digestive issues, check out our article What Causes a Bloated Belly and How to Get Rid of It?
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For Which Conditions Is a Gluten-Free Diet Recommended?
Healthy individuals have the advantage of choosing whether to eat foods containing gluten or not. On the other end of the spectrum are those who cannot make that choice freely, as they must avoid gluten for health reasons to prevent further worsening of their condition.
1. Coeliac Disease
Coeliac disease is an autoimmune disorder caused by gluten intolerance. The human immune system perceives gluten as a foreign substance and reacts with inflammation that damages the lining of the small intestine. This can lead to increased intestinal permeability (“leaky gut”), compromising the protective function of the intestinal barrier. [8]
Symptoms of Coeliac Disease
- Diarrhea or constipation
- Abdominal pain
- Reduced appetite
- Unexplained weight loss
- Impaired absorption of nutrients (vitamins, minerals)
- Fatigue
- Headaches
- Skin rash
Diagnosis of Coeliac Disease
- Blood tests: Testing for antibodies against tissue transglutaminase or deamidated gliadin peptides.
- Small intestine biopsy: A small sample of the small intestine’s lining is taken for laboratory evaluation.
Treatment of Coeliac Disease
A lifelong gluten-free diet, leading to the gradual regeneration of the small intestine’s lining and alleviation of symptoms. For most coeliacs, a safe gluten threshold is 20 mg per day, which is a tiny amount found in about 0.16 g of white wheat bread.
2. Dermatitis Herpetiformis (Duhring’s Disease)
This rare autoimmune skin condition is most commonly associated with coeliac disease. It is characterized by itchy, blister-like lesions that resemble herpes sores, appearing on various parts of the body. Unlike coeliac disease, not all patients with dermatitis herpetiformis experience intestinal damage. [12]
Symptoms of Dermatitis Herpetiformis
- Itchy, blistering rashes, most commonly in the elbow crease, knees, back, or head
- Digestive problems similar to those in coeliac disease (diarrhea, bloating, abdominal pain)
Diagnosis of Dermatitis Herpetiformis
- Skin biopsy: A skin sample is tested for antibodies.
- Blood tests: Evaluating antibodies against tissue transglutaminase, as in coeliac disease.
Treatment of Dermatitis Herpetiformis
A strict lifelong gluten-free diet, which leads to the gradual disappearance of the skin rash. Medications may also be used to relieve itching and reduce inflammation.
3. Non-Coeliac Gluten Sensitivity (NCGS)
Also known as gluten intolerance, NCGS presents with symptoms similar to coeliac disease but without the inflammatory damage to the small intestine. [9]
Symptoms of NCGS
- Diarrhea or constipation
- Abdominal pain
- Bloating
- Reduced appetite
- Fatigue
- Headaches
Diagnosis of NCGS
- Exclusion of coeliac disease and wheat allergy
- Diagnosis confirmed if symptoms subside after removing gluten from the diet and return when gluten is reintroduced.
Treatment of NCGS
Eliminating gluten from the diet. However, the diet doesn’t need to be as strict as in coeliac disease and often depends on individual tolerance.
4. Wheat Allergy
This is an abnormal reaction that occurs almost immediately after consuming wheat-containing foods. It is not an allergy to gluten itself, but to proteins found in wheat. [10]
Symptoms of Wheat Allergy
- Skin rash
- Nausea
- Abdominal pain
- Breathing difficulties
- Anaphylactic shock in extreme cases
Diagnosis of Wheat Allergy
- Blood tests: Testing for specific antibodies.
First Aid for Acute Wheat Allergy
In the case of a severe allergic reaction, anaphylactic shock can occur, posing a life-threatening risk. Breathing difficulties, throat swelling, paleness, or speech issues may arise. In such cases, call emergency services immediately, loosen tight clothing to aid breathing, and if the person is conscious, seat them upright with back support. Administer epinephrine (EpiPen) as soon as possible, which individuals with severe allergies usually carry.
Treatment of Wheat Allergy
Exclude wheat and wheat-containing foods from the diet. Even gluten-free foods may contain wheat starch, which is tolerated by coeliacs but not by people with wheat allergies. In case of acute symptoms, antihistamines (allergy medications) are used.
5. Gluten Ataxia
A rare autoimmune disease of the brain caused by an abnormal immune response to gluten, leading to damage in the cerebellum, which controls movement coordination. [11]
Symptoms of Gluten Ataxia
- Impaired coordination and balance
- Difficulty walking
- Speech problems
- Tremors
Diagnosis of Gluten Ataxia
- Neurological examination: Evaluation of coordination, reflexes, and muscle control.
- Blood tests: Presence of antibodies against gliadin.
- MRI: Brain imaging.
Treatment of Gluten Ataxia
A lifelong gluten-free diet can prevent further neurological damage. Eliminating gluten also helps gradually improve coordination.
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How Can I Tell if Gluten Is Causing My Issues?
Have you noticed that after eating bread, pasta, or pizza, you feel unwell and have digestive problems? First, check if your symptoms match those commonly associated with gluten intolerance. [13]
|
Other Symptoms |
|
|---|---|
| Abdominal pain Bloating Diarrhea or constipation Nausea Vomiting |
Weight loss Fatigue Skin problems Headaches Difficulty concentrating (“brain fog”) Joint pain Irritability, mood swings, or even depression |
Is Gluten Really the Culprit?
If you have any of these symptoms, don’t panic and don’t immediately eliminate all gluten-containing foods from your pantry. The cause could be something else, such as fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs), found in some vegetables, fruits, and legumes. Therefore, it’s essential to get tested and determine the exact cause of your symptoms.
1. Keep a Food Diary
Eat as you normally would, but start keeping a detailed record of your meals and note how you feel afterward. Record if you felt nauseous, had abdominal pain, diarrhea, or anything else that might be related to food. Also, include the time you ate and how long after eating the symptoms appeared. The more details you note, the more useful the information will be during a consultation with a doctor.
2. Visit a Doctor
If your symptoms persist and your food diary suggests that certain meals are causing problems, it’s time to contact a doctor. Start with your general practitioner, who can perform basic tests, like blood tests for antibodies. They may refer you to specialists (gastroenterologist, allergist, dietitian) for specific tests to diagnose allergies or coeliac disease. A dietitian can also assess your diet and help identify the cause of your issues.
Home Test for Gluten Intolerance
You can check your gluten tolerance with a home test kit. This test includes everything you need to take and evaluate a blood sample, detecting the presence of IgA antibodies, which appear with gluten intolerance. Regardless of the result, it’s recommended to see a doctor for a comprehensive diagnosis.
3. Elimination Diet
As part of the diagnosis, an elimination diet is commonly used. In this process, a specific component, such as gluten, is removed from the diet for several weeks (3–4), and its effects are monitored. If your symptoms improve during this time, you’ve likely identified the cause of your discomfort. To confirm, gradually reintroduce the component and observe if the symptoms return. Keep in mind that an elimination diet should not be done while you’re still being diagnosed, as it could distort the results. [14]
4. Final Diet Adjustment
The entire diagnostic process should ideally lead to a diagnosis and treatment plan. If this includes a gluten-free diet or other dietary modifications, you’ll need to learn which foods are suitable and unsuitable, and adjust accordingly. If you’ve never followed a medical diet before, this might feel overwhelming at first. Don’t worry, it just takes time to familiarize yourself with food labels. The important thing is to feel better. A dietitian or specialist can help you select suitable foods and design a balanced meal plan.
Gluten-Free Diet
A gluten-free diet is essential for treating coeliac disease or non-coeliac gluten sensitivity. All foods containing gluten, such as wheat, rye, barley, and oats (unless labeled gluten-free), must be eliminated. This includes obvious foods like wheat bread, pizza, pasta, or cakes, but gluten can also hide in less obvious foods like soy sauce, spices, condiments, deli meats, or pickled meats.
Since gluten is an allergen, according to legislation, it must always be highlighted in product ingredients in large letters or bold type.
How to Recognize Gluten-Free Foods?
1. Be Cautious with Risky Foods
Some food categories are more prone to containing gluten than others. Always check the ingredients to see what was used in their preparation. For store-bought items, this information is available on the packaging, while fresh products like baked goods may have ingredient lists near the shelf or you can ask staff. It’s best to buy gluten-free bread from specialized stores. Risky foods include:
- Sweet and savoury pastries
- Confectionery products
- Side dishes like dumplings and porridges
- Cereals and cereal bars
- Sweet and salty snacks
- Spices, seasonings
- Ready-made meals
2. Read the Labels
Get used to spending more time shopping at first. Carefully read the ingredient list of every product before putting it in your cart. Look for labels like “gluten-free,” or “does not contain gluten”. This is often accompanied by a symbol of a crossed-out wheat stalk. According to EU regulations, this label can only be used for products that contain less than 20 mg of gluten per 1 kg of food. This label may also be accompanied by phrases like “suitable for people with gluten intolerance” or “suitable for coeliacs.” [15]
You might also encounter the label “may contain traces of gluten,” which warns of potential unintentional contamination during production. However, the ingredients list must not contain any gluten-containing grains. Trace amounts can be up to 50 mg of gluten per 1 kg of food, which is above the safe threshold for coeliacs. [16]
Lastly, you might see the label “very low gluten content,” which indicates a maximum of 100 mg of gluten per 1 kg of food.
For more tips on how to read food labels, check out the article on How to Read Food Labels and What to Watch Out For.
3. Look for Hidden Sources of Gluten
Be especially cautious of hidden gluten sources, particularly in cooked dishes. For example, soups or sauces may be thickened with flour, or flour may be used to coat baking dishes. Flour can also be added to meatballs, various plant-based meat alternatives, and ready-made meals. Always stay alert when trying new foods.
Suitable Foods for a Gluten-Free Diet
At first, it might feel overwhelming as you learn which foods are gluten-free and how to substitute gluten-containing ingredients. Gluten plays a key role in baking and cooking, which can make gluten-free products like bread and pasta harder to prepare. However, modern gluten-free baking techniques have improved, and you’ll soon find your favorite products or learn to bake your own perfect gluten-free bread at home.
- When planning your meals, focus on basic ingredients.
- Just like with a regular balanced diet, ensure every meal contains the right proportion of proteins, carbohydrates, and fats.
- By cutting out gluten, you eliminate one of the richest sources of fibre, which is regular wholegrain bread. Therefore, it’s essential to monitor your fibre intake (at least 25 g per day) from allowed sources such as fruits, vegetables, legumes, quinoa, and gluten-free bread.
List of Gluten-Free Food Groups
|
Recommended Gluten-Free Foods |
|
|---|---|
| Grains | Rice, quinoa, millet, buckwheat, amaranth, sorghum, corn, gluten-free oats, rice porridge, buckwheat porridge, tapioca |
| Fresh Produce | Fruit, vegetables, mushrooms, potatoes, sweet potatoes |
| Legumes | Beans, lentils, peas, chickpeas, soybeans, legume pasta |
| Dairy Products | Milk, cheese, plain yogurt, cream, cultured dairy drinks |
| Fats | Natural seeds and nuts, nut butters, oils, butter |
| Proteins | Meat, fish, eggs, tofu, tempeh |
| Drinks | Water, coffee, tea, 100% fruit juices, gluten-free beer, wine |
| Snacks | Rice cakes, corn popcorn, gluten-free crackers, gluten-free crisps |
| Gluten-Free Breads | Gluten-free bread, rice cakes or corn thins |
The mentioned foods are naturally gluten-free, but always check the ingredients. For example, yogurts or plant-based dairy alternatives may be thickened with wheat starch.
Gluten-Free Recipes
You can find more gluten-free meal inspiration on our blog.
What Should You Remember?
Gluten has been a natural part of the human diet for thousands of years. Recently, however, more people are intentionally avoiding it. In some cases, it’s a necessity and part of treatment, for example, in celiac disease or non-celiac gluten sensitivity. However, it often happens that people switch to a gluten-free diet because they believe it will help them lose weight or eliminate digestive issues.
However, simply eliminating gluten in such cases may not be enough, and in most cases, it’s not even necessary. If you suspect gluten intolerance, it’s advisable to consult a doctor and undergo a comprehensive examination. If the diagnosis is confirmed, it is necessary to follow a gluten-free diet, which will help alleviate the symptoms. However, it is not true that a gluten-free diet is automatically healthier or that it will lead to weight loss. It is primarily intended for therapeutic purposes.
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Sources:
[1] Raju, S. A., Rej, A., & Sanders, D. S. The truth about gluten! – https://doi.org/10.1017/S0007114522001933
[2] Beyond Celiac. What Is Gluten.– https://www.beyondceliac.org/gluten-free-diet/what-is-gluten/
[3] München, L.-I. für L.-S. an der T. Gluten in wheat: What has changed during 120 years of breeding? – https://phys.org/news/2020-08-gluten-wheat-years.html
[4] Fernández-Pérez, S., Pérez-Andrés, J., Gutiérrez, S., Navasa, N., Martínez-Blanco, H., Ferrero, M. Á., Vivas, S., Vaquero, L., Iglesias, C., Casqueiro, J., & Rodríguez-Aparicio, L. B. The Human Digestive Tract Is Capable of Degrading Gluten from Birth. – https://doi.org/10.3390/ijms21207696
[5] Examine. Does gluten make you fat? – https://examine.com/articles/erd-sneakpeek18-does-this-gluten-make-me-look-fat/
[6] Summa Health.Gluten Digestive Issues Explained.– https://www.summahealth.org/flourish/entries/2021/03/gluten-digestive-issues-explained
[7] Verywell Health. How Gluten Belly Feels and Looks. – https://www.verywellhealth.com/gluten-belly-8364892
[8] Celiac Disease Foundation. What is Celiac Disease? – https://celiac.org/about-celiac-disease/what-is-celiac-disease/
[9] BeyondCeliac.org. Non-Celiac Gluten Sensitivity.– https://www.beyondceliac.org/celiac-disease/non-celiac-gluten-sensitivity/
[10] ACAAI Patient. Wheat & Gluten Allergy.– https://acaai.org/allergies/allergic-conditions/food/wheat-gluten/
[11] Beyond Celiac. Gluten Ataxia and Celiac Disease.– https://www.beyondceliac.org/celiac-disease/related-conditions/gluten-ataxia/
[12] Celiac Disease Foundation. Dermatitis Herpetiformis.– https://celiac.org/about-celiac-disease/related-conditions/dermatitis-herpetiformis/
[13] Cleveland Clinic. Gluten Intolerance: Symptoms, Test, Non-Celiac Gluten Sensitivity. – https://my.clevelandclinic.org/health/diseases/21622-gluten-intolerance
[14] Cleveland Clinic. Why and How To Start an Elimination Diet. – https://health.clevelandclinic.org/elimination-diet
[15] Eurofins Scientific. Labelling, certification and analysis of gluten-free foods. – https://www.eurofins.de/food-analysis/food-news/food-testing-news/labelling-of-gluten-free-foods/
[16] celiak.cz. Principy bezlepkové diety. – https://celiak.cz/bezlepkova-dieta/principy-bezlepkove-diety/
[17] Brouns, F., & Shewry, P. R. Do gluten peptides stimulate weight gain in humans? – https://doi.org/10.1111/nbu.12558
[18] Food52. Why You Should Resist the Urge to Tear into Hot Bread. – https://food52.com/blog/14727-why-you-should-resist-the-urge-to-tear-into-hot-bread