What is Gluten and Where is It?


That word on its own sounds kind of weird, don’t you think? It reminds me of the words glutton, glutes, and glue. Although they all have very different meanings. 

What do you think about when you see or hear the word gluten? For some, it doesn’t really mean anything, but for others it can mean a whole lot when it comes to their health, especially for those suffering with celiac disease, non-celiac gluten sensitivity, or wheat allergy.

What is Gluten?

Gluten is simply a protein.

More specifically it is a complex mixture of proteins naturally found in the seeds (grains) of a family of grasses – four in particular. 

Gluten takes up residence in all species and in all forms of: 

  • Wheat 
  • Rye
  • Barley
  • Triticale (a hybrid cross between wheat and rye)

Gluten then is found in all foods and ingredients that are made from these grains. Beverages, too, may contain gluten (beer and some other alcoholic beverages).

In culinary applications, gluten acts as a binder that helps foods maintain their shape, providing elasticity and moisture. It allows bread products and baked goods to rise, yielding the chewy texture we desire in them. 

The word “gluten” is of Latin origin and literally means “glue.”

Gluten is also often used as a stabilizer or thickening agent in the production of foods such as candy, gravies, rouxs, salad dressings, sauces, and soups.

It is added to foods and other products through extraction methods. Manufacturers do this to add protein, texture, and flavor.

Molecular Gluten

On the molecular level, there is a lot to be said about gluten, but I will try to sum up the science so it’s easy for you to digest. 😅

So we know that gluten is a protein…right? 

→ Amino acids are known as the building blocks of proteins. 

→ → Two major amino acids that make up gluten are glutamine and in larger amounts, proline. 

→ → → And proteins that are mostly comprised of proline are called prolamines. 

One subfamily of prolamine contains gluten, the others do not.

→ → → → The gluten-containing prolamine subfamily is where we find wheat, rye, and barley and each has its own specific gluten protein(s):

  • Wheat – gliadin & glutenin
  • Rye – secalin
  • Barley – hordein
Molecula structure of Gliadin, a gluten protein from wheat
Simple protein molecule, a prolamine, derived from the gluten of wheat, rye, etc. A toxic factor associated with celiac disease.

The above image was sourced from the National Center for Biotechnology Information. “PubChem Compound Summary for CID 17787981, Gliadins” PubChemhttps://pubchem.ncbi.nlm.nih.gov/compound/Gliadins. Accessed 14 January, 2022.

And even though we are talking on the molecular level, gluten proteins are still long molecules that need to be broken down even further. Digestive enzymes do that for us, but not completely. 

Undigested gluten then passes into the small intestine. The amino acids proline and glutamine can be difficult for some humans to digest, especially in people who are predisposed to gluten intolerance and celiac disease.

And there you have it. That’s gluten.

What is Gluten Found In?

Gluten-containing foods on the perimeter (bread, spaghetti, crackers, cereal with the word GLUTEN in the middle.

Here is the short list of where gluten is found.

Gluten-Containing Grains (and anything made from them)
WHEAT– includeswheat berries, bulgar, durum, emmer, semolina, spelt, farina, farro, graham, KAMUT, Khorasan wheat, einkorn wheat, wheat starch* (see NOTE below)
Common Foods: breads, cakes, pastries and other baked goods, breading, crackers, croutons, cereals, flour and pancake mix, granola and granola bars, pastas, noodles, and rice mixes, sauces, sauce mixes, gravies
Common Foods: breads and crackers (rye and pumpernickel), cereals, rye beer
Common Foods: Malt in various forms including malted barley flour, malted milk or milkshakes, malt beverage, malt extract, malt syrup, malt flavoring, malt vinegar, maltose, Ovaltine, foods that contain malt, beer, food coloring and soups, Brewer’s Yeast – this is a byproduct of beer-making and contains gluten from barley malt that was used to brew beer.
Common Foods: breads, cereals, pasta
*NOTE: Wheat starch that has NOT been processed to remove the presence of gluten to below 20 ppm and does NOT adhere to the FDA Labeling Law is assumed to still contain gluten. Some wheat starch is certified gluten-free wheat starch. This type of starch is considered to be safe for those who require gluten-free foods because it has been processed to remove gluten. For more information read this.

Did you know that gluten particles from gluten-containing foods often come into contact with foods and ingredients that naturally do not contain gluten. This is called cross-contact of gluten and is a concern for many people.

FACT: Several commercial food operations share preparation equipment with gluten-containing foods. As a result, some naturally gluten-free foods can come into contact with gluten during processing, making it unsafe to eat for the gluten-free crowd.

Are Oats Gluten-Free?

That’s a good question. Oats are naturally gluten-free. 

However, oats can often come into cross-contact with gluten-containing grains in fields where they are grown, but also during transport or in processing plants. 

Pure, uncontaminated oats, tested and labeled as gluten-free, are available and are considered safe to consume for people suffering with celiac disease or non-celiac gluten sensitivity.

Gluten in Medications, Supplements, Cosmetics, and…

Gluten can be found in non-food items and supplements. This includes but is not limited to the following:

Is GLUTEN in your medication or supplement? A left hand holding medications with the right hand holding a scoop of protein powder.
  • Prescription and over-the-counter medications – manufacturers may use gluten as a binding agent. Consult a pharmacist or physician regarding gluten concerns in these items.
  • Dietary supplements (vitamin, herbal or nutritional) – those that contain wheat gluten must have “wheat” stated on the label. Gluten* is not required to be declared on the label.
    • *These items must be verified as gluten-free by reading the label or checking with the manufacturer.
  • Lipstick, lip gloss, lip balm and other cosmetics
  • Play-Doh
  • Communion Wafers

Why is Knowing More About Gluten and its Sources Important?

To put it bluntly, some people just can’t eat gluten.

Some people with certain health conditions must avoid it. If they don’t, they won’t feel well and they put their health at risk. It can cause severe intestinal damage for some.

Sometimes it can be very serious if someone comes into contact with wheat gluten, too; it can be life-threatening.

The main reasons why most people avoid gluten is due to:

  • An allergy to wheat proteins 
  • A gluten intolerance 
  • Celiac disease or other gluten-related condition that may or may not be symptomatic

Regardless of symptoms, ingesting gluten can negatively affect the health in these populations.

Learn more about these conditions in my blog post “National Gluten-Free Day 2022: A Gluten Free Dietitian Speaks.”


Knowing the facts about gluten and where it is can definitely be a challenge. This is especially true since modern foods rely heavily on gluten.

From baked goods to frozen pizza to boxed cereals to packaged noodles, and in soups, dressings, condiments, and beverages – gluten-containing products can be found in nearly every grocery store aisle and hidden in foods you would not ever suspect. 

When in question, read food labels and contact food manufacturers if consuming gluten-containing foods and products is a concern for you or someone you know. 

Want to know more about gluten and where it is found? Please leave a comment below!

National Gluten Free Day 2022: A Gluten Free Dietitian Speaks

Julie Christensen

Julie Christensen, RD, LD is a Registered and Licensed Dietitian with over eleven years of experience in the field of dietetics, specializing in Wellness and Disease Prevention, Heart Health, Weight Management, and Celiac Disease. She holds a dual Bachelor of Science degree in Dietetics and Nutrition, Fitness, & Health as well as a Bachelor of Arts degree in Psychology and is a member of the Academy of Nutrition and Dietetics.

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