Impact of Nondigestible Oligosaccharides on Gut-Associated Lymphoid Tissue and Oral Tolerance Induction

Human milk is very rich in nondigestible oligosaccharides, which support colonization of Bifidobacteria and Lactobacilli and immune maturation. Manufactured nondigestible oligosaccharides are added to infant formula in order to mimic functional aspects of human milk oligosaccharides. They support the growth of beneficial microbes and reduce gastrointestinal and respiratory infections. Furthermore they reduce the risk of developing allergic disease when provided early in life. Oral tolerance induction is key in the prevention of allergies. Environmental factors such as dietary constituents and the colonization with commensal microorganisms at the mucosal surface are crucial for the generation of mucosal tolerance. Evidence is building that nondigestible galacto- and fructo-oligosaccharides can either directly or indirectly modulate the GALT and systemic immune system in health and disease. Besides increasing IL-10 and IgA in mice and human, they were found to induce functional regulatory T-cells in spleens of mice affected with cow’s milk allergy. In addition, they induce galectin-9 capable of IgE neutralization. The immunologic basis by which nondigestible oligosaccharides may affect the mucosal and systemic immune system is discussed in this book chapter.