Health promoting aspects of milk oligosaccharides

Human milk contains a large variety of oligosaccharides (HMOs) with the potential to modulate the gut flora, to affect different gastrointestinal activities and to influence inflammatory processes. Human intervention or clinical studies are still missing as the large amounts of milk oligosaccharides needed are not yet available. Therefore, there is great interest in sources of oligosaccharides other than those from human milk. Although the amount of oligosaccharides in milk of most animal species is low compared with human milk, recent data indicate significant differences among milk from farm animals. Whether some of these oligosaccharides are good candidates for human studies needs to be further investigated. Currently, there is only a limited amount of quantitative data on the total amount of oligosaccharides and on individual components in animal milk, e.g., in bovine, goat or buffalo milk. Regarding biological functions certain structural prerequisites are necessary for milk oligosaccharides to be effective in different in vitro systems. Often prebiotic oligosaccharides (PBOs) from plants are obtained by technological means and are considered to be similar or even identical to HMOs. However, there is no evidence for this speculation as PBOs are structurally quite different from HMOs. Whether PBOs exert comparable functional effects remains to be investigated. If this were the case their addition to infant formula may be useful in the context of mimicking biological functions of human milk constituents.