For oat products to be considered gluten-free, they must show less than 20ppm of gliadin. In a recent study, nine of twelve samples from three major brands of oats showed gluten levels ranging from 1,807 to 23 ppm, which exceeded the gluten free requirement. Therefor, only certified gluten free oats should be consumed by those with celiacs. Gluten free certified oats are typically tested for gliadin to less than 3ppm, and are considered safe for celiacs who are not sensitive to Avenins.