Gluten in Foods: Where It Is and Where It Isn't

People look for gluten in ingredients not only if they have celiac disease — there is a lot of confusion around it. Below is a calm breakdown: what it consists of, where it really is, and which foods are blamed unfairly.

What gluten is

Gluten, or glutenin, is a group of similar proteins (prolamins and glutelins) in cereal seeds. In wheat they make up 75–85% of total protein. The names differ: gliadins in wheat, hordeins in barley, secalins in rye, avenins in oats. These proteins give dough elasticity and help it rise — which is why gluten is so valued in baking.

On average, a person eats 10–40 grams of gluten per day. The main part is in bread, pasta, and baked goods, where it makes up 10–15% of dry weight.

Which grains and foods contain gluten

The three main sources are wheat, barley, and rye. Close by are spelt, khorasan, emmer, einkorn, and triticale. Oats themselves do not contain gluten, but they are often produced near wheat, barley, and rye and become contaminated by them; a small proportion of people with celiac disease also react to pure oats.

Next are products made from these grains. A short list of the ones people ask about most often:

• bread and bakery products — most types;
• macaroni and pasta;
• cakes and cookies;
• breakfast cereals and flakes;
• most types of beer, which is made from barley.

Gluten can also be in certain sauces and in some prepared dishes — it is not always clear from the name.

Is there gluten in potatoes, vegetables, and fruits

No. Gluten is found in wheat, barley, and rye, while potatoes, vegetables, fruits, and bananas are not related to these grains. For prepared dishes, check the ingredients: breaded potatoes or the sauce poured over them can add gluten.

Hidden gluten in prepared foods

Gluten is cheap and technologically useful, so it is added where a thick texture is needed: in ice cream, ketchup, gravies, and minced meat. Milk is not a grain. It is better to read the ingredients of prepared sauces on the package: gluten is sometimes used as a thickener.

There are also non-food sources: vitamins, supplements, toothpaste, mouthwash, and lip balm. Gluten from cosmetics is not absorbed through the skin, but a reaction is possible if a little is accidentally swallowed. If the ingredients are not listed on the package, check with the manufacturer rather than assuming the product is gluten-free by default.

Foods that do not contain gluten

Besides potatoes, vegetables, fruits, and bananas, rice and corn are also safe: their proteins (zein in corn, rice protein) are sometimes also called gluten, but they do not harm people with celiac disease. Reading the ingredients on the package helps spot hidden gluten.

Who especially needs to know about gluten and when to see a doctor

This is primarily about celiac disease — an autoimmune condition in which the immune system attacks the body's own tissues and damages the small intestine, so that nutrients stop being absorbed. Celiac disease can occur at any age, it is more often noted in women, and mild cases may remain unrecognized.

The risk is higher in first-degree relatives — parents, brothers, sisters, children — and in people with type 1 diabetes, autoimmune thyroid diseases, Down syndrome, and Turner syndrome. Symptoms vary: diarrhea, abdominal pain, bloating, gas, constipation, indigestion, fatigue, unexplained weight loss, itchy rash, difficulty conceiving, coordination problems. In children — stunted growth and delayed puberty.

Diagnosis is a blood test and a biopsy of the small intestinal mucosa during upper gastrointestinal endoscopy. Similar symptoms occur with wheat allergy and with gluten sensitivity, but with sensitivity the intestine is not damaged.

Gluten itself is not a reason to call an ambulance. 103 or 112 — if difficulty breathing or another life-threatening reaction appears after eating, which can happen with wheat allergy.

This material is for reference and does not replace a doctor's consultation: if your well-being is concerning, discuss it with a doctor.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer