Gluten is a kind of protein that can be found in wheat and species related to it, such as rye and barley. It is found in most kinds of bread and cereals. It should be noted though that not all grains contain gluten, mainly because they lack the glycoprotein gliadin. Examples of these non-gluten grains are corn, buckwheat, wild rice and oats.

Gluten is what gives bread its elastic property, which enables the dough to retain its shape. It is also responsible for the chewiness of bread when eaten. Reducing the gluten from flour makes it less elastic, and one of the practical uses of lessening gluten is for making cakes. Increasing gluten makes food chewier, and the practical use for this can be seen on imitation meats.

When gluten is removed from wheat flour, the product is wheat starch. Not all of the gluten in wheat flour, however, can be removed. Usually, products labeled ‘gluten-free’ is not totally free of gluten, but only meets the percentage of gluten removed as recommended by the FDA.

There are some people who have adverse reaction to gluten consumption. Some 1% of the US population suffer from a sensitivity to gluten, called coeliac (or celiac) disease. This disease causes people to have an abnormal reaction to gliadin that is digested partially. Coeliac disease is an autoimmune disorder of the small intestines. The only treatment effective in combating this disease is going on a gluten-free diet.