Schematic overview of oligosaccharides, with survey on their major physiological effects and a focus on milk ones

While Biochemistry textbooks for University degree courses do not deal with oligosaccharides, this subject is now becoming essential in Biomedical Sciences for several reasons. Oligosaccharides are currently used in foods and beverages for their useful physicochemical and prebiotic qualities, albeit their excessive consumption may have side effects. They are also essential components of milk, where they exert a protective role on infants acting as stimulants for the development of immune system and gut microbiota. Oligosaccharides are seen as an alternative to improperly used antibiotics in the diet for monogastric animals and considered promising safe anti-parasite treatments in agriculture. Besides, they are widely used in both cosmetics and pharmaceutics. For these reasons, biotechnological research is hardworking on new enzymes able to synthesize them in a great variety. At the same time, oligosaccharides belong to the so-called FODMAP (Fermentable Oligo-, Di- and Monosaccharides And Polyols) group of compounds, whose decreased use in diet is beneficial to several syndromes of the digestive tract. The scope of this review is to give a general and schematic view of oligosaccharides. We describe the structure, source and use of several of the most known oligosaccharides, focusing on their health implications. Main groups in human milk and their substitutes in infant formulas are also reported. In the end some of the most recent studied oligosaccharides and their promising applications are discussed.