A large number of people may have Celiac Disease and not even know. Another reason for this is the large and varied list of symptoms.
At the beginning of the month, I posted a fun little infographic about symptoms, but I didn't talk about it very much.
Because there are so many different possible symptoms, Celiac Disease often looks a little different in everybody. Some people present with typical symptoms: bloating, gas, stomach pains, constipation, diarrhea, weight loss. And some people present with rather atypical symptoms: headaches, mouth sores, joint pain, infertility, or hair loss. And there's another group of people who don't present with any symptoms at all! Imagine finding out you have a disease like this without ever experiencing a symptom!
Celiac Central has a lovely web page about all of this, and they even have a checklist for you if you've wondered if you may have Celiac disease.