"The tests identified several potential fillers, including rice, soybean and grasses such as wheat that could pose a health concern for people allergic to those plants and for consumers seeking gluten-free products"
Be sure to try elimination herbal products if you are still experiencing symptoms on the gluten-free diet.
It looks like this did not include products that were labelled gluten-free.
This was a Canadian study. Do people think that it could be a problem in the US as well?