Why is a Stool Test a Logical Test for Gluten or Other Food Sensitivity?
The immune cells present in the intestinal tract comprise the largest mass of tissue in the body assigned the function of protecting against foreign invaders. These invaders are present in the form of proteins called antigens. Although the intestine’s immune cells probably evolved originally to ward off infecting organisms, in fact, their most frequent exposure to foreign antigens comes from food. One of the first lines of defense against foreign antigens (food or infections) is the secretion of a special antibody called secretory IgA into the intestinal lumen (i.e., the hollow center of the intestine). Here, these antibodies bind the antigen by a sort of lock and key recognition mechanism, in an attempt to neutralize the antigen so that it cannot enter the body. Because these antibodies do not get reabsorbed after entering the intestinal tract, they travel all the way through the intestine where they can be recognized in the stool.
