Gluten is a protein found in wheat, rye, barley and in some cases oats. It can be found in breads, pastas or as a food additive in the form of a flavoring, stabilizer or thickening agent in products like ketchup and ice cream.

Those with the gastrointestinal coeliac disease are required to eat a gluten-free diet. The legal definition of gluten varies from country to country, as do the labeling requirements. In the UK, for example, cereal containing gluten has to be marked as such, but sausages may contain gluten additives.

Those avoiding gluten can get their grains and starch from corn, potatoes, rice, tapioca, arrowroot, quinoa, sweet potato, taro and yams. Pure buckwheat is gluten-free despite its misleading name, but watch out, as many industrial buckwheat products include wheat flour.

Gluten can also be found in vitamins, lip balms and over-the-counter medicines.