Gluten

If you’ve just been diagnosed with coeliac disease, “gluten” is suddenly the most important word in your vocabulary. But most people have only a vague sense of what it actually is. Knowing the specifics makes the diet easier to navigate — and makes it easier to explain to anyone cooking for you.

What Gluten Actually Is

Gluten is not a single protein. It’s the collective name for a family of storage proteins found in three grains: wheat, barley, and rye. In wheat, the relevant proteins are gliadins and glutenins — together, they form gluten when flour is mixed with water. In barley, the equivalent is hordein. In rye, it’s secalin.

These proteins are what give bread its elasticity and chewiness. They form a stretchy network when dough is kneaded, trapping gas bubbles and creating structure. From a baking perspective, they’re useful. From a coeliac perspective, they’re the problem.

When someone with coeliac disease eats gluten, their immune system identifies these proteins as a threat and launches an attack — not just on the gluten itself, but on the lining of their own small intestine. This is the autoimmune response that defines coeliac disease. It’s not an allergy. It’s not a sensitivity to “processed food.” The immune system is attacking the body’s own tissue.

Grains that contain gluten:

• Wheat (including spelt, kamut, einkorn, emmer, durum, semolina, bulgur, freekeh, farro)
• Barley (including malt, malt extract, malt vinegar, barley flour)
• Rye

Grains that do not contain gluten:

• Rice, corn (maize), oats (with caveats — see Avenin and Oats), millet, sorghum, teff, buckwheat, amaranth, quinoa, and more

Oats sit in a complicated middle ground. They don’t contain gliadin, hordein, or secalin, but they do contain avenin — a similar protein that some coeliacs react to. Most certified gluten-free oat products address the cross-contamination issue but not the avenin question. The two issues are separate.

What This Means for You

Avoiding gluten means avoiding wheat, barley, and rye in all forms — as ingredients, as additives, as flavourings, and in cross-contamination. It’s not about avoiding “bread and pasta” specifically; it’s about understanding which grains trigger the immune response and being thorough about eliminating them.

Related in the Coeliac Alphabet: Hidden Gluten · Wheat Starch · Oats · back to the full A–Z.