What does gluten do in the body?

See the post What Is Gluten?

Since some people's bodies see gluten as a foreign substance, the result of gluten intolerance is often called "leaky gut." The intestinal lining gets destroyed by the attack the body mounts on the "invader." The lining of the small intestine becomes destroyed to the point that nutrients are no longer absorbed properly (classic Celiac), resulting in problems like osteoporosis and digestion/maldigestion issues like IBS. In addition, gluten seems to trigger the body to produce excess zonulin, which is the substance that regulates what passes through the digestive tract into the blood stream. Zonulin, in my understanding, also helps open the blood-brain barrier, meaning that undigested gluten can actually get to and affect the brain itself. The result of this is that gluten can also cause psychological symptoms as well, much like a drug.