Gluten is the name given to the protein in wheat, rye, barley and oats that affect people with coeliac disease. It is a composite name representing
Gliadin in Wheat
Hordein in Barley
Secalin in Rye
Avenin in Oats
The current tests for gluten can measure gliadin, hordein, and secalin but not avenin as it is a slightly different protein. Accordingly it is prohibited under the Food Standards Code to use oats in foods labelled or advertised as gluten free. When people discuss gluten free oats (and laboratories advise that oats are gluten free) what should be said is that they are free from wheat (and rye, barley) gliadin i.e. there is no measurable contamination.
Avenin is an essential part of oats (as gliadin is with wheat). Oats will never be gluten (i.e. avenin) free [even if they are described as gluten (i.e. gliadin) free]. As mentioned in The Australian Coeliac magazine on several occasions, Dr Robert Anderson has found that approximately 1:5 people with coeliac disease react to pure uncontaminated oats i.e. they react to oat avenin.
Since we cannot determine who is the 1:5 and we know that damage can occur in the absence of symptoms, Dr Anderson’s advice (and Coeliac Australia’s) is that oats should not be consumed without a biopsy prior to and during consumption.