The intestine is an organ involved with absorbing, processing, and transporting food into the body. However, if one were to assess the immunological portion of the intestine and compare it with better-known immunologically functioning organs such as the spleen, the intestine would be found to be the largest such organ and the extent of its immunologic function would be found to be equally proportionate. The mucosal surface of the intestine has the ability to respond to effector cells capable of protecting the host from potentially harmful organisms or local antigens. When there is increased intestinal permeability (Leaky gut syndrome), pathogenic bacteria and its products, toxins, antigens, chemicals and incompletely digested food penetrate the intestinal epithelium and are transported throughout the body. They activate the immune system and effect the pathophysiology of acute and chronic inflammatory disease and autoimmune disease. Therefore, by a better understanding of the importance of gut barrier function and the pathophysiology of gut related immunologic disease, we can make helpful suggestions for achieving optimal intestinal health.