Hi Patrick, you would have to get a test done to determine this. I do not know my 'secretor type' yet, so have to ver on the side of caution if I'm not sure, or sometimes, take an element of chance (like the ocassional bowl of oatmeal). I have noticed though, that a lot of the Avoids do me no good, even things like herbs and supplements, so I'm looking into this a lot closer.