When gluten reaches the digestive tract and is exposed to the cells of the immune system, they mistakenly believe that it is coming from some sort of foreign invader, like a bacteria. In certain people who are sensitive to gluten (celiak disease), this causes the immune system to mount an attack against it.
Some people believe that there are health benefits to gluten-free eating for the general population, but there is no published experimental evidence to support such claims. A significant demand has developed for gluten-free food in the United States whether it is needed or not. Peter H.R. Green, MD, director of the Celiac Disease Center at Columbia University stated that the gluten-free market is expanding greatly. This expansion is extremely valuable for those with celiac disease or other medical reasons, such as gluten intolerance or sensitivity. However, a gluten-free diet does not hold the same benefits for the general public.