What Is Gluten?
by Sarah
______________________________________________________________________________________________________________________________________________________________________________________________________Gluten is at the heart of gluten intolerance, yet most people can’t properly answer the basic question, what is gluten? I’ll try to provide you a clear, comprehensive and useful gluten definition.
When people ask what is gluten online, they usually find themselves with vague, inaccurate or confusing answers. I’ve seen answers from so-called authority sources defining it as a “sticky, elastic substance,” which is true to a degree but vague and not terribly helpful, a “protein,” which is not completely accurate as gluten is a protein composite not a protein itself, and a “3-dimensional network formed from sulfur cross-linkage among proteins,” which is only accurate when kneading gluten-containing dough and not a very useful description for most casual researchers.
My goal is for you to be able to leave this page with not only a clear definition for what is gluten, but also with a comprehensive source you can refer back to when you address different issues relating to gluten, whether from a cooking perspective (in baking or gluten-free baking) or from a health perspective (in celiac disease or a non-celiac gluten sensitivity).
Each section will start with a relatively simple and usable explanation, then move to more detailed and complicated explanations of various facets of gluten and gluten’s uses. So if you are looking for a quick answer, you can read the first part of each section and move on. If you want more technical detail on gluten, read each section in full.
Use the following outline to navigate this comprehensive answer to What Is Gluten?
- What Is Gluten?
- What Are Gluten’s Uses?
- How Is Gluten Extracted?
- What Is Gluten Intolerance?
- What Is Gluten Enteropathy?
- What Is Gluten Withdrawal?
- What Foods Contain Gluten?
- What Is A Gluten Free Diet?
What Is Gluten?
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In the simplest terms, what is gluten? Gluten is a protein composite, meaning it is a substance made up of several different proteins, in wheat and related grains in the triticeae family of grassy grains or cereal grains. These grains include barley, bulgur wheat, durum, einkorn, farro, graham, kamut, rye, semolina, spelt, triticale and wheat.
Gluten Origin
Gluten comes from the endosperm within the seeds of these cereal grains (the adjacent picture shows an example of a wheat seed endosperm). This makes gluten proteins plant storage proteins. Storage proteins essentially feed embryonic plants during germination, a process common among the seeds in most flowering plants.
The proteins in gluten are unique storage proteins, however, in that they are also functional proteins. This unique functionality makes wheat difficult to substitute when creating gluten-free baked goods, as I describe in the next section on What Are Gluten’s Uses?
The four primary proteins in gluten are albumins, globulins, glutelins and prolamins. In wheat gluten (or gluten in cereal grains), glutelins and prolamins are far more prevalent than albumins and globulins. Albumins and globulins are the primary storage proteins in corn gluten and rice gluten and are not associated with gluten intolerance. Some take issue with the food industry for even using the terms corn gluten or rice gluten.
The specific proteins constituting gluten that we are most interested in are the prolamin gliadin and the prolamin-like glutelin glutenin. They make up about 80 percent of the protein in wheat. These are the proteins which give gluten its unique structure and function… and these are the proteins responsible for triggering gluten intolerance symptoms, celiac disease symptoms and a non-celiac gluten sensitivity.
The cross-linking of gliadin molecules and glutenin molecules creates the primary properties we identify as what is gluten.
Prolamins are insoluble in water and are a general family of proteins common among these grassy grains. In fact, all the grassy grains related to wheat contain different prolamins, but since the polypeptide chains (sometimes just referred to as peptides) of each of these proteins is so similar to the proteins in wheat, they are still broadly called gluten. For example, while gliadin is the prolamin in wheat, secalin is the prolamin in rye and hordein is the prolamin in barley. These are also known as glycoproteins.
Glutelins are another prolamin-like family of proteins. The glutenin in gluten is a glutelin. Glutelins are heat-labile proteins, which means they are altered by heat (which is important for appreciating how gluten responds to baking), and are insoluble in water but soluble in dilute acids or alkalies (bases). While researchers consider the gliadins the more damaging proteins in gluten for people with celiac disease, the glutenins in gluten have also been shown to trigger a damaging autoimmune response in people with a genetic susceptibility to gluten.
Gluten also contains proteins called albumins and globulins, which are soluble in water or diluted salt water unlike the gliadins and glutenins. These are common storage proteins in many grains and do not greatly contribute to the unique quality of gluten-containing cereal grains. They are not known to trigger the problems triggered by glutenins and especially gliadins. When you see websites define gluten, they often don’t mention albumins and globulins because they are far less significant than glutenins and gliadins when discussing gluten intolerance.
Small side note: I’ve had people write me asking what is gluton? This is a common misspelling. The correct spelling is gluten, not gluton. Unlike with celiac vs. coeliac (which are both correct in different contexts), I haven’t found a context where the spelling gluton would be appropriate.
What Are Gluten’s Uses?
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Because of the cross-linking of gliadins and glutenins, which occurs when you mix a gluten-containing grain with water, gluten provides the chewiness you’ve come to know in baked goods. Baked goods with a higher density of gluten feature greater chewiness (as is the case with bagels and pizza crust). Without gluten, common baked goods would be more sticky and less chewy.
Gluten also traps carbon dioxide produced during dough fermentation before baking, helping dough rise before it is baked. Additionally, gluten traps gases during the baking process, helping baked goods rise even more while baked. This capacity to trap gas also helps provide the light, flaky quality in some baked goods.
When a gluten-containing dough is baked, gluten coagulates to help that bread, muffin or cake retain its shape. This is why early attempts at gluten free bread and gluten-free baking in general tend to result in baked goods that crumble more than we desire.
Heavier, chewier baked products feature higher concentrations of gluten while lighter pastry products feature a lower concentration of gluten. People in the flour industry measure the concentration of gluten (or more precisely the density and elasticity of gluten) within flours using a Farinograph. This measurement helps determine the best cooking or baking role for a particular gluten-containing flour.
The food industry uses gluten, and wheat gluten in particular, in many ways because it is so easy and inexpensive to isolate gluten from starches. As it is a concentrated protein and an absorbent substance, gluten is often used as a food additive, a protein supplement or even as a food by itself. Meat substitutes, also known as imitation meat or wheat meat, are often composed of concentrated gluten. For example, seitan is mostly concentrated wheat gluten.
Perhaps most insidiously, gluten’s capacity to bind and provide thickness makes it common in flavorings and sauces. This is why gluten exists in many more food products than just the obvious baked products.
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Wheat starches are used in many products, partially because they are a cheap by-product of vital gluten manufacturing. Because gluten proteins can’t be completely removed from the wheat starch, products made with any amount of wheat starch are still dangerous for people with any kind of gluten intolerance or gluten allergy symptoms.
How Is Gluten Extracted From Wheat?
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Because gluten is insoluble in water, gluten is easily isolated by kneading whole wheat flour and rinsing it with water. If you knead wheat flour rigorously while slowly rinsing it with water, you will eventually have what looks and feels like an elastic rubber ball. That is the gluten isolated from the starches.
What Is Gluten? The image above shows how gluten looks when isolated from about a cup of wheat flour by kneading it under a standard kitchen faucet for five minutes.
IMPORTANT: It is not possible to completely remove all gluten proteins from a wheat starch. While various forms of the process I just described will separate the starches from the gluten of a wheat flour, significant traces of gluten and its various proteins will remain in the starches. This is why if you are on a gluten-free diet you absolutely must avoid any product containing even a trace of wheat, wheat starch or starch from one of the cereal grains in the triticeae tribe.
Mass producing gluten (usually from wheat gluten) involves using heavy machinery to knead a slurry of whole wheat flour — wheat flours mixed with cold water or saline solution — so the gluten isolates and collects into a distinct gluten mass. A centrifuge collects that gluten mass and passes it to machinery to remove moisture.
First a screw press is used to remove most of the water, then the gluten passes into an evaporation chamber, where the temperature is raised just enough to dry the gluten mass without altering it.
At this point the gluten resembles a flour with minimal moisture. Finally the gluten flour is milled and sifted into the density and evenness required for the intended end product. When you see vital wheat gluten sold in stores or listed as an ingredient, it probably came from this gluten isolation process.
What Is Gluten Intolerance?
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The term gluten intolerance is really an umbrella term, and underneath that umbrella we have three fundamentally different conditions. The two primary forms of gluten intolerance are celiac disease and a non-celiac gluten sensitivity. Additionally, some people can suffer from a wheat allergy, which is quite different from celiac disease or non-celiac gluten sensitivity, but since it is a food allergy involving wheat you will often see people discuss it alongside gluten intolerance.
When most people use the term gluten intolerance, however, they are likely referring to celiac disease.
Only in the spring of 2011 did doctors and researchers verify and isolate the existence of a non-celiac gluten sensitivity. Unfortunately, because a separate and distinct form of gluten sensitivity has only recently been isolated and defined, diagnosis can be difficult. At this point, the most likely scenario for being diagnosed with a gluten sensitivity is simply testing negative for both celiac disease and a wheat allergy yet still exhibiting clear signs of a poor response to consuming gluten. Currently doctors and researchers are trying to develop more clear and useful biomarkers for diagnosing a non-celiac gluten sensitivity.
When taken all together, these different forms of gluten intolerance indicate some startling gluten intolerance statistics.
What Is Gluten Enteropathy?
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Gluten Enteropathy, or gluten-sensitive enteropathy, is simply another name for celiac disease, which you will also find called celiac sprue disease, non-tropical sprue or endemic sprue. In different parts of the world celiac is spelled coeliac, which just furthers the confusion.
Celiac disease is an autoimmune disease that manifests itself primarily in the small intestine. It occurs in people who inherit one or both of the celiac genes, which are HLA-DQ2 and HLA-DQ8.
When people with celiac disease consume gluten, the enzyme tissue transglutaminase alters the gliadin in the gluten, which causes an immune system reaction that damages the lining of the small intestine. This is why celiac disease is called an autoimmune disease: the immune system attacks its own body.
This reaction causes inflammation and damages the villi or microvilli along the walls of the small intestine (a phenomenon labeled villous atrophy). These microvilli are tiny hair-like fingers that reach out from our small intestine walls to grab nutrients from food passing through our bowel. When the villi are truncated, we are less able to absorb nutrients from our food.
In addition, this damage creates a phenomenon called intestinal hyperpermeability, more often simply referred to as leaky gut syndrome. When you suffer from leaky gut syndrome, both gluten fragments and toxins that should have remained in your small intestine pass through your intestinal wall into your bloodstream.
It is the combination of these two phenomena — villous atrophy and intestinal hyperpermeability — that cause the broad range of possible celiac disease symptoms.
We don’t know what triggers people to become celiacs. That might sound odd as you might assume that gluten triggers people to develop celiac disease. But suffering from the reaction to gluten is the disease; what we don’t know is what causes somebody who is genetically predisposed to finally develop the disease.
Some people who are genetically susceptible may go most of their lives without developing celiac disease or suffering from a poor response to consuming gluten. Something takes us from susceptibility to manifestation, and scientists still haven’t identified that exact trigger.
What Is Gluten Withdrawal?
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When people eat gluten, it triggers the body to manufacture exorphins, which are opioid chemicals similar to endorphins. This produces a calm, relaxed feeling. And just as opiates cause withdrawal when opiate consumption is stopped, you can experience a degree of withdrawal when you completely remove gluten from your diet.
To make things worse, people who need to go gluten-free often need to go dairy-free or casein-free as well, and casein, the primary protein in cow’s milk, also triggers the body to manufacture exorphins.
This withdrawal can cause irritability and intense cravings you don’t expect or understand.
Additionally, as your body heals during the first week or so of going gluten-free, you may experience some mild rashes, hives and headaches. This is because your body, and in particular your liver, can suddenly better process and eliminate toxins. When you go through this kind of detox period you may experience some temporary symptoms or side-effects resulting from your body working through and eliminating these toxins.
I suspect when many people saw the heading what is gluten withdrawal they didn’t expect to find such a distinct and potent answer.
What Foods Contain Gluten?
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This is the most intimidating and frustrating topic in this What Is Gluten guide. I’ll provide you an outline and foundation for all the foods containing gluten, but I’m afraid you’ll need to flesh this list out with some of your own research as needed. A single static and complete list just isn’t possible as brands, recipes and formulas are constantly changing. Please always check the label and never assume anything.
When in doubt, contact the manufacturer. And because the person answering the phone or your email may not always fully understand what is gluten, be prepared to ask if any of the terms, products or ingredients mentioned below are in the products (such as wheat starch, hydrolyzed protein, or even non-wheat gluten products, such as barley or rye).
Recent gluten-free labeling guidelines released by the FDA in the United States should make this process a little easier eventually, but it will take some time for them to be useful for the average consumer.
Most Common and Potent Source of Gluten: Wheat
First, we start with any food made from — or supplemented with — one of the cereal grains in the Triticeae tribe:
- Barley
- Bulgur wheat
- Durum
- Einkorn
- Farro
- Graham
- Kamut
- Rye
- Semolina
- Spelt
- Triticale
- Wheat
The most important here are wheat, barley and rye, especially wheat and barley. Each of these make it into foods as hidden sources of gluten because different parts of them are used as flavor enhancers, binders, thickeners, protein enhancers and more.
Wheat starch — which despite being separated from gluten still contains significant and harmful traces of gluten — must be avoided and you will often find it used in sauces like soy sauce, barbecue sauce or hydrolyzed flavor enhancers. Malted barley also makes it into a ton of foods as a primary ingredient (like in beer, which is why it can be hard to find good gluten free beer) or as a flavor enhancer (like in malted milk). Any product suggesting a wheat germ was used in it will also contain gluten.
The following is a strong foundation list of foods containing gluten, but please understand a comprehensive list would be far larger. I still hope it is enough to give you a more clear and helpful picture of what you must avoid.
This list includes foods that can and often do contain gluten, but in some cases you can find variations of them that are gluten-free. In some cases, an item on the list may be fine, but I put it on this list to alarm you to a food you may need to further research.
- Bouillon
- Bran
- Breakfast Cereals
- Broth (Chicken Broth, Beef Stock and Vegetable Stock, including Stock Cubes)
- Burgers
- Canned And Prepared Soups
- Cooking Wines
- Couscous
- Cured Meats
- Dextrin
- Flavored And Herb Cheeses
- Flavored Coffees
- Flavored Dairy Products, Like Yogurt And Pudding
- Flavored Liqueurs And Liquors
- Flavored Vinegars
- Gravy
- Herbal Teas (Barley is sometimes added)
- Hot Dogs
- Imitation Meats or Meat Substitutes (even when they’re Soy-Based)
- Instant Coffee, especially Flavored Instant Coffee
- Jerky
- Ketchup (or “Catsup”)
- Marinades
- Matzo
- Orzo
- Pickles
- Roasted Or Flavored Nuts
- Salad Dressings
- Sauces
- Sausage
- Seitan
- Self-Basting Poultry
- Soy Sauce
- Spice Blends (including Curry Powders)
- Tamari
- Veggie Burgers
- Veggie Dogs
- Veggie Sausages
And while the following should be obvious, you can never be too safe:
- Bagels
- Biscuits
- Bread
- Cakes
- Croissants
- Muffins
- Pancakes
- Pasta
- Pastries
- Pie Crusts
- Pizza Crusts
- Pretzels
Because gluten can be used as a stabilizing agent and thickener, the number of subtle, hidden sources of gluten can be alarming. For example, some manufacturers use gluten in the sticky stuff you use to seal envelopes!
One last area: oats. I’m developing an entire guide to gluten in oats because it has become so confusing and controversial. The bottom line is that oats by themselves are technically gluten-free, but in most cases they are not safe for people on a gluten-free diet because of cross contamination. Oats are so often grown and processed alongside gluten-containing grains that they are almost always cross-contaminated.
To makes things even more difficult, just because an oat product is certified gluten-free doesn’t mean you should splurge. A small percentage of people who are sensitive to gluten are also sensitive to the storage proteins in oats, so even if you want to start eating certified gluten-free oats, you should only do so slowly and with your physician’s supervision.
You will need to be diligent about reading labels and you will need to grow accustomed to regularly contacting manufacturers.
What Is A Gluten Free Diet?
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Of course the simple definition is that a gluten-free diet is a diet that strictly excludes gluten. To understand what that means you need to understand what is gluten and what is gluten intolerance, but you also have to understand how manufacturers and researchers define the term gluten-free.
Simply put, you’ll discover some confusing and controversial elements to the term gluten-free and what has been defined as acceptable on a gluten-free diet.
First, when you see something labeled as gluten-free, that means that it contains less gluten than the minimum standard considered to be harmful. Unfortunately, that minimum standard varies all over the world and is a bit controversial.
The FDA set guidelines to define a gluten-free food as a food containing less than 20 ppm (parts per million) gluten, or a food with 0.002% gluten. This is the same as the international Codex Alimentarius standard. But in Australia they have determined that a food must contain 5 ppm gluten (0.0005% gluten) to be considered gluten-free.
When you embark on a gluten-free lifestyle, you must make certain you obtain enough fiber, folate, iron, niacin, riboflavin, selenium and thiamine. These are nutrients often lacking in a gluten-free diet because they are often fulfilled by gluten-containing foods on a standard diet. In addition, you need to be careful you don’t fill your diet with too many simple carbohydrates.
When you go gluten-free, you still need to try to eat gluten-free whole grains and gluten-free nuts. Too many refined flours like white rice flour will not provide you a healthy way forward. Replacing relatively healthful gluten-containing grains with too many simple carbs often leads to the phenomenon of gluten intolerance and weight gain.
My Gluten Free Pantry may be a good starting point for people learning how to replace gluten in their everyday baking.
Because you may need to avoid lactose or casein as well, at least when you first start your recovery, you may have to avoid dairy products. So calcium and protein will also need to be monitored and you may need to be deliberate in how you replace these nutrients.
Discover a helpful list of gluten-free foods in the following section on my home page: What Is Gluten Free?
And that ends my comprehensive guide to What Is Gluten? I don’t expect you to read this entire guide in one session, but I hope you will bookmark it and refer to it as you need.
It is a strange phenomenon, but you would be surprised how many people living a gluten-free lifestyle can’t really answer the seemingly simple question, what is gluten? If you’ve followed along here, now you will be one of the few people who can.
