Thanks for the response.

My latest b12 was 700-odd, that was after b-vit supplements. Was 350-ish before then so obviously had some room to absorb more.

Yes I agree with the steep learning curve. Before the high iGg result my gluten free diet was mainly avoiding pure gluten foods like bread, pasta etc, thinking a small amount won't hurt me. Am now aware of contamination even from using a toaster etc, so am going to be a lot more strict from now on and hopefully see some big improvements.