The law on gluten-free has two categories:

1. Foods containing 20 parts per million (ppm) gluten or less - Only foods that contain 20 ppm or less can be labelled as 'gluten-free'. This includes specialist, substitute foods on prescription and in the Free From section of the supermarket. Also, some mainstream foods that are labelled gluten-free.
2. Foods containing above 20 and no more than 100 ppm gluten - Specialist substitute products (such as breads and flour mixes) that contain Codex wheat starch with a gluten level between 21 and up to 100 ppm may be labelled as ‘very low gluten’.