Based on what is currently known, it's a big leap to attributing autism and other problems to gluten, and an even bigger one to prescribing gluten-free eating as a treatment. It's possible that some people benefit from a gluten-free regimen for reasons that have less to do with gluten and much more to do with the structure involved in planning and sticking to such a strict eating plan.

In the context of celiac disease, gluten refers to the protein of grains capable of provoking an autoimmune response. Other grains also contain protein, but wheat, barley, rye, and spelt contain varieties that aren't broken down by digestive enzymes:

• in wheat, the difficult-to-digest protein is gliadin;
• in rye - secalin; 
• in barley - hordein.

In people with celiac disease, when they get absorbed into the walls of the small intestine, the immune system misreads the situation, views them as intruders, and unleashes a furious inflammatory response that damages tissue.