What is Gluten?

With millions suffering from gluten intolerances and celiac disease, our awareness of gluten has risen substantially in recent years. But do you know what it actually is, how it can affect some people, and what gluten-free really means? Our nutrition team answer some of the most frequently asked questions on the topic. 

Gluten refers to a group of proteins that are found in some, but not all, grains. These grains include wheat, barley, rye and triticale (a cross between wheat and rye). The two main gluten proteins are called gliadin and glutenin.

What does gluten do?

Gluten is a major ingredient in many baked goods. When you add water to flour, the sticky dough texture is due to gluten[1]. Gluten forms a network that holds water in the structure. Gliadin allows dough to rise during baking and fermentation by trapping air, which forms pockets[2]. Glutenin gives dough its strength and elasticity[2]. The more the dough is mixed, the stronger the gluten network becomes changing the final product texture from light and crumbly to chewy. So longer mixing is desirable for bread, but less so for cake. Without gluten, the well-loved characteristics of many baked goods are lost. As gluten forms a complex network, it can be hard to replicate with other ingredients[3].

What is Celiac disease and non-celiac gluten insensitivity?

Celiac disease is a chronic autoimmune condition[4]. It occurs because the body detects gluten that is ingested as a threat, similar to a virus. As a result, antibodies are produced, particularly in the gut, that subsequently cause inflammation and damage the lining of the small intestine. The symptoms of celiac disease include a variety of gut issues, fatigue, joint pain, and deficiencies in micronutrients, such as iron[4]. Celiac disease may only present a few general symptoms, so can go undiagnosed[5]. If you feel you have such symptoms or a relative has celiac disease, it’s important to schedule a screening to determine a proper diagnosis.

Non-celiac gluten insensitivity (also known as gluten intolerance) is diagnosed when an individual experiences intestinal distress, headaches, and fatigue, amongst other symptoms, as a result of consuming gluten-containing foods but has not been diagnosed with celiac disease or wheat allergy, although some symptoms may overlap[6]. Self-diagnosis does not mean an individual has gluten insensitivity. In fact, many people who are self-diagnosed may have another dietary issue unrelated to gluten[7] or no issues at all[7, 8]. It has been found that of those who are self-diagnosed with gluten insensitivity, as little as 7% may actually have symptoms as a result of gluten consumption[8].

Another chronic autoimmune condition caused by gluten is called dermatitis herpetiformis. It is often linked to celiac disease but has a lower prevalence in the population of approximately 0.03%[9]. Dermatitis herpetiformis is characterized by itchy blisters/rashes, most commonly found on the elbows, knees, and buttocks[10].

Are people avoiding gluten unnecessarily?

It depends on the individual. If you have celiac disease, wheat allergy, or non-celiac gluten sensitivity then the answer is no. Around 1% of the population suffer from celiac[11]. It is highly likely that the number of people with non-celiac gluten insensitivity is higher in the general population, however, due to self-diagnoses and lack of medical consultation, there is considerable debate around the number of people affected by non-celiac gluten insensitivity[12]. The average figure appears to be approximately 6%[13]. If you do not have any of the aforementioned conditions, then you do not need to avoid gluten. If you feel you might, it is important to get a professional medical diagnosis. Additionally, a dietitian will be able to ensure your diet and health do not suffer as a result of avoiding certain foods.

If someone doesn’t need to avoid gluten and does, are there any benefits?

Beyond managing gluten-related disorders the answer is no. In fact, a gluten-free diet can have negative consequences as a result of dietary restriction. It has been shown to result in an inadequate intake of fiber and magnesium, along with several other micronutrients[14, 15] and an increase in sugar consumption[16]. People who follow a gluten-free diet may well have a nutritious diet however, it’s important to understand that eliminating certain foods does not automatically make a diet more nutritious. The reason that a gluten-free diet can have such consequences is that some gluten-free products may be higher in sugar and fat while being low in wholegrains[17].

Furthermore, gluten-free alternatives tend to be over twice as expensive as their gluten-containing counterparts[18] while being of a lower quality, particularly in terms of texture[17].

Is gluten-free a fad?

It’s hard to define what a fad diet is, without pointing to examples, even though the term has existed for over 100 years[19]. If someone is looking towards a gluten-free diet to improve the quality of their diet or for weight loss, then eliminating gluten is unlikely to help directly.

For those who must avoid gluten because of a dietary condition it is certainly not a fad. The increase in media coverage of “gluten-free” has improved the availability and variety of gluten-free options[20]. It has also made “gluten-free” a more present sign on food labels. On the other hand, it has created more confusion around what celiac disease is and how that differs from those who choose not to eat gluten for other reasons[20].

What foods are gluten-free?

Most foods are gluten-free. This includes meat, poultry, nuts, seeds, dairy and fruit, and vegetables. Although the most commonly consumed grains contain gluten, not all do. Some examples of gluten-free grains are corn, oats, buckwheat, and quinoa. It’s important to note that grains naturally free of gluten may become contaminated during growing or processing if they come into contact with gluten-containing grains.

Processed foods can contain gluten when you may not expect them to, such as soy sauce. Although the labeling of gluten-free foods is not required there are laws surrounding it. A food can only be labeled as gluten-free if it contains 20ppm or less[21].

How are gluten-free foods made?

To ensure all ingredients are gluten-free they must be grown in a separate, controlled environment. Different crops can often be grown in neighboring fields or in the same field one after another, which can result in gluten contaminating naturally gluten-free crops. Once harvested the ingredients must be transported, handled and packed in a gluten-free environment. This may involve an entirely separate factory or a different part of the same factory where separate equipment and clothing is used. Additionally, a thorough cleaning procedure and adequate time (over 24 hours) between handling gluten-containing and gluten-free ingredients must be in place.

Gluten-free flours including tapioca, rice, and corn flours can be used in replacement of gluten-containing flours, namely wheat flour. Additional ingredients such as emulsifiers to improve mixing, fibers for thickening and hydrocolloids to bind water may be added to a food that traditionally would contain gluten to replicate its varied functions[17].

Are oats gluten-free?

Oats are naturally gluten-free. However, as mentioned above they are an example of a grain that can become contaminated with gluten. As a result, oats are often certified as suitable for people with celiac disease by being grown and processed in a gluten-free environment (22). Around 8% of those with celiac disease appear to have a reaction to gluten-free oats (23). This may be due to avenin. Avenin is another prolamin protein similar in structure to gluten which can cause an autoimmune response.

Are Huel products gluten-free?

Huel offers a range of gluten-free products, including the Black Edition powder, Ready to Drink, Complete Protein, Huel Powder v3.1, Daily Greens, and some Instant Meals. The Black Edition powder is made without oats, making it a great option for those with oat sensitivities. Some gluten-free products such as the Huel v3.1 powder and Ready to Drink are made with gluten-free oats. All gluten-free Huel products are batch tested and confirmed to contain less than 20ppm of gluten.


  1. Biesiekierski JR. What is gluten? Journal of gastroenterology and hepatology. 2017; 32 Suppl 1:78-81.
  2. Barak S, et al. Influence of Gliadin and Glutenin Fractions on Rheological, Pasting, and Textural Properties of Dough. International Journal of Food Properties. 2014; 17(7):1428-38.
  3. Bunning F. Gluten-Free Baking. 2017. Available from: https://routt.extension.colostate.edu/wp-content/uploads/sites/4/2018/05/9.376-Gluten-Free-Baking.pdf.
  4. NIH. Celiac disease. Date Accessed: 10/30/19. [Available from: https://ghr.nlm.nih.gov/condition/celiac-disease]
  5. Rubio-Tapia A, et al. Increased prevalence and mortality in undiagnosed celiac disease. Gastroenterology. 2009; 137(1):88-93.
  6. Leonard MM, et al. Celiac Disease and Nonceliac Gluten Sensitivity: A Review. Jama. 2017; 318(7):647-56.
  7. Biesiekierski JR, et al. No Effects of Gluten in Patients With Self-Reported Non-Celiac Gluten Sensitivity After Dietary Reduction of Fermentable, Poorly Absorbed, Short-Chain Carbohydrates. Gastroenterology. 2013; 145(2):320-8.e3.
  8. Lionetti E, et al. Re-challenge Studies in Non-celiac Gluten Sensitivity: A Systematic Review and Meta-Analysis. Frontiers in Physiology. 2017; 8(621).
  9. West J, et al. Incidence and prevalence of celiac disease and dermatitis herpetiformis in the UK over two decades: population-based study. The American journal of gastroenterology. 2014; 109(5):757-68.
  10. National Institute of Diabetes and Digestive Kidney Disease. NIH. Dermatitis Herpetiformis. Date Accessed: 10/30/19. [Available from: https://www.niddk.nih.gov/health-information/digestive-diseases/dermatitis-herpetiformis]
  11. Singh P, et al. Global Prevalence of Celiac Disease: Systematic Review and Meta-analysis. Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association. 2018; 16(6):823-36.e2.
  12. Catassi C, et al. Non-Celiac Gluten sensitivity: the new frontier of gluten related disorders. Nutrients. 2013; 5(10):3839-53.
  13. Sapone A, et al. Spectrum of gluten-related disorders: consensus on new nomenclature and classification. BMC Medicine. 2012; 10(1):13.
  14. Tavakkoli A, et al. Characteristics of patients who avoid wheat and/or gluten in the absence of Celiac disease. Digestive diseases and sciences. 2014; 59(6):1255-61.
  15. Vici G, et al. Gluten free diet and nutrient deficiencies: A review. Clinical nutrition (Edinburgh, Scotland). 2016; 35(6):1236-41.
  16. Wild D, et al. Evidence of high sugar intake, and low fibre and mineral intake, in the gluten-free diet. Alimentary pharmacology & therapeutics. 2010; 32(4):573-81.
  17. El Khoury D, et al. A Review on the Gluten-Free Diet: Technological and Nutritional Challenges. Nutrients. 2018; 10(10).
  18. Missbach B, et al. Gluten-free food database: the nutritional quality and cost of packaged gluten-free foods. PeerJ. 2015; 3:e1337-e.
  19. Diet and Diet Fads. The Hospital. 1908; 45(1160):173-4.
  20. King JA, et al. Experiences of coeliac disease in a changing gluten-free landscape. Journal of human nutrition and dietetics : the official journal of the British Dietetic Association. 2019; 32(1):72-9.
  21. FDA. Questions and Answers: Gluten-Free Food Labeling Final Rule. Date Accessed: 10/30/19. [Available from: https://www.fda.gov/food/guidanceregulation/guidancedocumentsregulatoryinformation/allergens/ucm362880.htm#Gluten_Levels]
  22. Gilissen LJWJ, et al. Why Oats Are Safe and Healthy for Celiac Disease Patients. Medical sciences (Basel, Switzerland). 2016; 4(4):21.
  23. Hardy MY, et al. Ingestion of oats and barley in patients with celiac disease mobilizes cross-reactive T cells activated by avenin peptides and immuno-dominant hordein peptides. Journal of Autoimmunity. 2015; 56:56-65.

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