The oats are contaminated with gluten myth is popular amongst gluten-free casein-free dieters who appear to react to oats. It is not true.

Numerous certified gluten-free oat brands are available and these have been processed in factories that do not handle wheat, and these oats do not contain even trace amounts of hidden gluten.

Oats do not naturally contain gluten but contain a gluten-like protein called avenin to which some individuals react. Current scientific research on coeliacs is confused and contradictory, with some studies showing that coeliacs have a good tolerance of oats, whilst others suggest they do not. It is likely that a subset of coeliacs react to oats whilst others do not. Further, different varieties of oats seem to vary in avenin content and structure.

Oat and other grain reactions are common amongst individuals following a Weston A. Price Foundation diet, which requires the dieter to soak and/or ferment all grains before use in order to destroy a relatively harmless antinutrient, phytic acid. This creates amines and glutamates to which individuals react.