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GUIDE · INGREDIENTS

Hidden gluten: where it turns up unexpectedly

Wheat, rye and barley are the easy part. The hard part is the dishes where you do not expect them: a wok with soy sauce, a thickened gravy, a meatball with breadcrumbs. This guide walks through the places that surprise people most often.

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4 min read · Last updated on 15 September 2026
In short
Gluten is in wheat, rye, barley and spelt — and in a long list of names that do not give that away. Thickeners, stock and soy sauce are the three most-missed sources in a restaurant kitchen. “Gluten-free” is regulated by law; “may contain traces” is not.

The grains, and the names that hide them

Gluten is in wheat, rye and barley, and in everything descended from them: spelt, kamut, durum and triticale. Those words rarely appear on a menu. What does appear is this:

  • Couscous, bulgur, orzo and semolina — all wheat.
  • Breadcrumbs, panko, rusk crumb and croutons.
  • Seitan: not something with gluten in it — it is gluten.
  • Malt and malt extract (from barley), and with them malt vinegar.
  • Oats contain no gluten themselves, but are almost always processed alongside wheat. Only oats explicitly sold as gluten-free are.

Sauces, soups and gravy: the thickener

This is the category most often forgotten in a restaurant, including by kitchens with good intentions. A sauce gets thickened, a soup gets finished, and the default thickener is flour.

So do not ask whether the sauce is gluten-free; ask what it is thickened with. Cornflour, cream or a reduction are fine; a roux of flour and butter is not.

  • Gravy, veloutés and classic sauces built on a roux.
  • Stock cubes and powders — many contain wheat.
  • Soy sauce and ketjap: traditionally brewed with wheat. Tamari is usually the gluten-free one, but that is printed on the bottle, not visible in the kitchen.
  • Ready-made marinades, teriyaki, hoisin and many Asian stir-fry sauces.

The genuinely unexpected places

And then the dishes nobody thinks of, because there is nothing bread-like about them.

  • Meatballs, sausage and burgers: breadcrumbs or rusk as a binder.
  • Liquorice: many kinds contain wheat flour.
  • Beer is brewed from barley. Gluten-free beer exists, but ordinary beer never is.
  • Surimi and some fish snacks contain wheat starch.
  • Ice cream with a biscuit in it — and more often: the same scoop used across every tub.
  • Seasoning mixes on crisps and snacks, and some sweets with wheat-based glucose syrup (that last one is usually fine; ask if you are unsure).
Medicines and supplements
Wheat starch is rare as an excipient in tablets. Rare is not never: when in doubt ask your pharmacist, not us.

What a label does and does not say

In a supermarket you have more certainty than in a kitchen, because the statement “gluten-free” is regulated across Europe. What is not regulated is the warning underneath it.

  • “Gluten-free”: below 20 milligrams of gluten per kilo. This is a legal limit, not a marketing term.
  • “Very low gluten”: between 20 and 100 milligrams per kilo. Not suitable for most people with coeliac disease.
  • “May contain traces of gluten”: a voluntary statement by the manufacturer about its own production line. There is no standard and no inspection behind it, so its absence is not a guarantee either.
  • The crossed grain symbol is used under licence and means a product has been checked against the gluten-free standard.

Frequently asked questions

The questions people ask most about this.

Is soy sauce gluten-free?

Traditional soy sauce is brewed with wheat, so no. Gluten-free versions exist, usually tamari, but in a restaurant it is rarely visible which bottle went into the wok. Ask before you order.

Is beer gluten-free?

Ordinary beer is not: it is brewed from barley. There are beers brewed gluten-free and beers made gluten-free, and they say so on the label. Cider, wine and pure spirits contain no gluten.

Can I eat oats?

Oats contain no gluten themselves, but are almost always processed in the same mills and factories as wheat. Only oats sold as gluten-free are reliable. Whether you tolerate oats is a question for your doctor or dietitian.

What does “may contain traces of gluten” mean?

That the manufacturer cannot rule out cross-contamination in its own production. It is a voluntary warning with no standard behind it, so you cannot read an amount from it — and its absence says nothing in itself.

No guarantee, but something to hold on to
This article gives you something to work with, not a guarantee: only the kitchen itself knows how it is working tonight. For medical questions about coeliac disease, or about what you can tolerate, see your doctor or dietitian — that is not ours to answer.

See what is known about gluten, per restaurant

We read a venue’s own website and menu and put the signals we find next to the experiences of visitors with coeliac disease.

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