My son and I both have celiac.
The Codex Alimentarius does allow up to (I believe) 20 ppm, but that amount CAN and DOES trigger reactions in some folks.
It's all a matter of how sensitive you-or more accurately, your immune system- are.
Some folks, like me, can handle touching it (good thing, as I work in a grain warehouse!), but can NOT ingest it, while others can't even touch it.
DH, if truly DH (meaning biopsied and verified for the IGa antibodies) is ALWAYS gluten-caused. There are Rx's for it, but that's masking the true cause (as are most other Rx's, but that's another soapbox
Neither my son or I had the classic symptoms, he had failure to thrive, anemia, growth delay, and chronic, severe constipation....I just had autoimmune thyroid/adrenal issues. After testing through enterolab for immunoglobin though, we're both positive. Docs were worthless-I was an 'overanxious mother'-right up til I pulled him off gluten and he went from being below the 3rd percentile in height and weight (having not gained any weight from age 16 mos to 27 months) to being in the 10th for each after about 9 months gluten free.
is awesome, and there are a bunch of blogs with good recipes, etc. It's my opinion, from experience, that anyone with persistent anemia should trial a gluten free diet for about 8 weeks to see if they feel better.