Gluten-free, and something else too

A gluten-free label answers one question. If you also avoid milk, or soy, or sesame, or you are shopping for a household where different people avoid different things, every product has to pass several checks — and the pack only helps with the first.

Specialist gluten-free products are a good example of the problem. A loaf, a pasta or a biscuit reformulated without wheat still has to be held together by something, and manufacturers reach for ingredients such as egg, milk proteins, soy, nuts, seeds or pulse flours to do it. None of that is hidden — it is on the ingredient list — but a shopper scanning the front of the pack for a gluten-free mark can easily stop reading before they get there.

The label rules add a second layer of work. The United States requires nine major allergens to be declared, with sesame added as the ninth on 1 January 2023 under the FASTER Act. The European Union requires fourteen, including celery, mustard and lupin, none of which is among the US major allergens. Anyone avoiding something beyond those lists — nightshades, say — has no declaration rule helping them at all, only the ingredient text.

One scan, every check

GlutenScanning is built around the idea that those three questions should cost one scan, not three readings of the same small print. Point the camera at a barcode and the app looks the product up in the OpenFoodFacts catalogue, reads the ingredient text behind it, and checks that text against gluten, more than 60 other allergens, and any dietary rules you have set — all in the same pass.

The coverage starts with all nine US major allergens — milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans and sesame — and carries on through more than 50 further allergens and intolerances, from celery and mustard to lupin, sulphites and nightshades. That matters most for the second and third questions, where the labelling rules stop.

Before anything is matched, the ingredient text is normalised and known-safe phrases are masked, so that buckwheat does not trip a wheat warning and maltodextrin does not trip a malt one. When several restrictions are in play, false alarms multiply quickly; an app that flags half of what you pick up stops being useful. Why buckwheat is not wheat explains that step in detail.

A verdict you can read, not just a colour

With more than one restriction, a bare red or green mark is not enough — you need to know which check failed. Each result leads with a plain-language verdict, then names the ingredient that triggered it, lists every allergen found, and attaches a confidence score. A product that is gluten-free but contains skimmed milk powder shows you exactly that, so you can decide whether it is a problem for you or for the person you are shopping for.

For looking things up rather than scanning them, the app has an encyclopedia of the allergens it tracks. Each one is tagged high, medium or low risk and listed with the aliases it appears under on ingredient lists, and each allergen’s page covers symptoms, common sources and the peer-reviewed citations behind the claims. A food ranking screen orders foods by allergen content score, which helps when you are choosing between two options rather than checking one.

When there is no barcode

Restaurant plates, bakery counters and home cooking have no barcode to scan. For those, you can photograph the meal and the analysis identifies the dishes in the photo and flags the allergens each is likely to carry. It is deliberately weaker evidence — it reads a plate, not a recipe — and works best as a prompt for the questions to ask rather than an answer. How to check food that has no barcode goes further.

Your restrictions stay on your phone

A list of what you cannot eat is health information, and it is treated that way. There is no account and no server-side profile: your scan history and dietary profile stay on the device. Analytics are anonymous and can be switched off in Settings. Barcode scanning also falls back to a local product database when there is no signal, which is useful in the back of a large supermarket; meal-photo analysis needs a connection.

What a scan cannot do

An ingredient list describes what a manufacturer added on purpose. It says nothing reliable about cross-contact on a shared line, and precautionary “may contain” statements are voluntary in the US and the EU, so their absence proves little. A scan also cannot see a recipe change before the product database catches up. What a “may contain” warning predicts covers the evidence on that. For life-threatening allergies, confirm with the manufacturer.

Common questions

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