According to recent studies by Dr. David Clark, the most common cross-reactor to gluten is coffee. When somebody with celiacs drinks coffee, it can cross-reacts with gluten antibodies. So what does that mean? It basically means that when you ingest coffee, your immune system may mistake these antibodies in your system are gluten, and therefore your body will react as if you have eaten something containing gluten.
I have personally found that these finding are very true to me. Before this study, I had always just thought that I was allergic to coffee as every time I would drink it, I would become violently ill. My allergy tests at the doctors office though would never show an allergy to coffee, but I stayed away from it regardless. These new findings have given me comfort in knowing that my body wasn't reacting to something else, and I will continue to keep coffee out of my diet.
There are ways that your doctor can test you to see if you have this reaction to coffee, but it's extremely expensive and takes time. Most experts just recommend that if you have been diagnosed with Celiacs, that you try and cut coffee from your diet. For those of you that this is asking the impossible, make sure you are cautious of how your body is reacting to the coffee you are drinking. Even though there are no traces of gluten in coffee, if your body is reacting in a negative way, you are causing some major harm to your immune system and your intestine. It's doing the same damage as eating gluten would.
Tea is an excellent substitute for coffee, and is offered in a variety of flavors and styles. I like to treat myself to some good quality, loose leaf teas from Teavana. It's a bit pricey, but the quality is fantastic and worth every penny. Also, they make a coffee like drink from cacao beans that is quite tasty! Make sure to check out your local health food store for some good quality tea and cacao drinks.