Effects of Prebiotics and Probiotics on the Host Immune Response

Abstract

The gastrointestinal (GI) tract is the largest interface between an animal’s internal milieu and its exterior environment. As such, it forms a physical barrier between the two environments. However, the function of the GI tract in the well-being of an animal is more complex than this passive role. The GI tract not only regulates the selective entry of nutrients while keeping vigilant against pathogens, it is largely responsible for shaping the immune response. Through specialized receptors and other general mechanisms, the GI tract senses changes in its environment and actively responds to the changes. These responses allow the intestine to contribute to the defense against microbes as well as control and regulate the local immune response. In addition, the luminal microbial ecosystem is a highly complex community of primarily bacterial microbes that communicates extensively with itself and the host. The microbial community has major influences on the host, including effects on nutrient absorption, cancer, inflammation, host metabolism, barrier function, and gut function (neuromotor, immunological, vascular) among others. Regulation of the immune response is the basis for the use of probiotics and prebiotics reviewed in this chapter.