Bovine milk as a source of functional oligosaccharides for improving human health

Abstract

Human milk oligosaccharides are complex sugars that function as selective growth substrates for specific beneficial bacteria in the gastrointestinal system. Bovine milk is a potentially excellent source of commercially viable analogs of these unique molecules. However, bovine milk has a much lower concentration of these oligosaccharides than human milk, and the majority of the molecules are simpler in structure than those found in human milk. Specific structural characteristics of milk-derived oligosaccharides are crucial to their ability to selectively enrich beneficial bacteria while inhibiting or being less than ideal substrates for undesirable and pathogenic bacteria. Thus, if bovine milk products are to provide human milk-like benefits, it is important to identify specific dairy streams that can be processed commercially and cost-effectively and that can yield specific oligosaccharide compositions that will be beneficial as new food ingredients or supplements to improve human health. Whey streams have the potential to be commercially viable sources of complex oligosaccharides that have the structural resemblance and diversity of the bioactive oligosaccharides in human milk. With further refinements to dairy stream processing techniques and functional testing to identify streams that are particularly suitable for enriching beneficial intestinal bacteria, the future of oligosaccharides isolated from dairy streams as a food category with substantiated health claims is promising.

Figure 1

Schematics of representative structures of HMO, BMO, GOS, and FOS. Linkages between monosaccharides are also shown and include the following: α1–2, α1–3, α2–3, α2–6, β1–3, β1–4, β1–6, and β2–1. The HMO structures can be elongated by repeating units of lactosamine (GlcNAc and galactose) and further decorated by sialic acid and fucose. The BMO structures can be further elongated with residues of GlcNAc, galactose, and sialic acids. Whereas characteristic HMO and BMO structures are branched and display a variety of α and β linkages, GOS and FOS are linear chains containing repeating units of galactose and fructose, respectively (depicted in brackets with a subscript of n < 7 and n < 10 repeating units, respectively).