Milk Bioactive Compounds and Gut Microbiota Modulation: The Role of Whey Proteins and Milk Oligosaccharides

Abstract

A strong correlation between the occurrence of various pathological conditions and intestinal dysbiosis is supported by a range of strong evidence. Vice versa, many pathologies have been shown, in turn, to be responsible for alterations in the gut microbiota, a condition that can worsen illness outcomes and response to therapies. For these reasons, great efforts have been made, and studies are still ongoing, to elucidate the mechanisms underlying gut microbiota alterations and to search for pharmacologic or other strategies that can effectively restore the gut microbiota. In this narrative review, we examined the most significant literature on the role of some milk bioactive compounds, such as milk oligosaccharides and whey proteins, in modulating the composition of the gut microbiota and the underlying mechanisms of action, with the aim of investigating the impact of the microbiota changes mediated by these milk bioactive molecules on human health, and their potential use as therapeutics to treat or adjuvate the treatment of gut dysbiosis and associated pathologies.

Keywords: glycomacropeptide; gut microbiota; lactalbumin; lactoferrin; lactoperoxidase; lysozyme; milk oligosaccharides; prebiotics; probiotics; whey proteins.

Figure 1

Prebiotic activity of lactoferrin: mechanisms of action. Both direct and indirect prebiotic effects have been described. The indirect mechanism is due to the lactoferrin-mediated iron sequestering that leads to a selective inhibition of the growth of pathogens, promoting the growth of those probiotics, such as Bifidobacterium and Lactobacillus, which do not necessarily need iron to grow. In the direct mechanism, lactoferrin promotes the growth of probiotics (especially Bifidobacterium) by acting as β-N-glycans and iron supplier, or by interacting with the lactoferrin-binding proteins present on the membrane of some probiotics, including Bifidobacterium and Lactobacillus. This interaction has been shown to promote the cytosolic internalization of lactoferrin which has been suggested to modulate genes involved in DNA replication and cell growth.