The nutritional role of free sialic acid, a human milk monosaccharide, and its application as a functional food ingredient

Abstract

N-Acetyl-d-neuraminic acid (NANA), more commonly known by its trivial name sialic acid, is an endogenous human and ubiquitous nutritional monosaccharide. As a bound sugar at the terminal positions of glycans NANA is known to play important roles in many biological events. The data that exist on the occurrence of the free monosaccharide in breast milk and nutrition, however, are less commonly discussed. In most foods of animal origin, sialic acid occurs as a mixture of NANA and N-glycolyl-d-neuraminic acid (NGNA), a hydroxylated derivative of NANA that is not found in humans. The dietary intake of NGNA has been identified as a risk factor for long-term adverse health effects. Therefore, we present summaries on the biochemistry, metabolism, bioavailability, and the data on NANA and NGNA levels that occur in diverse foods. Finally, we discuss the emerging data demonstrating that free NANA is linked to positive nutritional effects including pronounced antioxidative properties. These data and the extremely high safety profile of NANA justify dietary enrichment at levels that correspond to the dietary intake of NANA in infants through breast milk.

Toxicological safety assessment of the human‐identical milk oligosaccharide 3′‐sialyllactose sodium salt

“…Other structure‐specific anti‐infective mechanisms have also been proposed (Kim et al, ). N ‐Acetyl and N ‐glycolyl forms of sialic acid represent a difference in structure that inevitably contributes towards fighting infection and providing nutrition (Röhrig, Choi, & Baldwin, ), but these are not the only attributes being considered. The specificity between the 3′‐ and 6′‐isomers may also be vital to the recognition of serious pathogens such as the human influenza A/B viruses (Gagneux et al, ), and 3′‐SL has recently been reported to show preventive effects on rheumatoid and osteoarthritis in vitro and in mouse models (Jeon et al, ).…”

“…Other structure-specific anti-infective mechanisms have also been proposed (Kim et al, 2019). N-Acetyl and N-glycolyl forms of sialic acid represent a difference in structure that inevitably contributes towards fighting infection and providing nutrition (Röhrig, Choi, & Baldwin, 2017), but these are not the only attributes being considered.…”

Toxicological safety evaluation of the human‐identical milk oligosaccharide 6′‐sialyllactose sodium salt

“…Furthermore, freely occurring sialyllactoses have been confirmed to interfere with receptor binding of many of these pathogens (Laucirica, Triantis, Schoemaker, Estes, & Ramani, 2017;Marotta, Ryan, & Hickey, 2014). It is not only the subtle structural difference between the N-acetyl and N-glycolyl forms of sialic acid that plays an important role in the context of infection and nutrition (Röhrig, Choi, & Baldwin, 2017), but the difference between the 3′-and 6′isomers with a confirmed human upregulation of 6′-linked sialic acids being possibly linked to the evasion of critical pathogens such as influenza is also a contributing factor (Gagneux et al, 2003).…”

Relationship Between Oligosaccharides and Glycoconjugates Content in Human Milk and the Development of the Gut Barrier

“…Especially in the gut, sialic acid prevents the adhesion of pathogens and promotes the growth of Bifidobacteria (Egan, Motherway, Ventura, & van Sinderen, 2014). From a nutritional point of view, sialic acid is crucial for immune and cognitive development (Röhrig, Choi, & Baldwin, 2017). However, the presence of some glycans, such as the Gal (α1-3)Gal epitope present in bovine glycoproteins and not in HMGPs, have been linked with undesirable effects, such as allergic reactions (Rispens, Derksen, Commins, Platts-Mills, & Aalberse, 2013).…”