Prebiotics are undigestible carbohydrates that promote the growth of probiotic bacteria in the gut. Human milk contains a variety of oligosaccharides believed to be an important factor in the pattern of microflora colonization of breastfed infants. Because of variety, variability, complexity and polymorphism of the oligosaccharide composition and structure, it is currently not feasible to reproduce the oligosaccharide components of human milk in a strictly structural fashion.[110]