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.

KEYWORDS:

• Sialic acid
• breast milk
• human milk saccharides
• infant nutrition
• antioxidant

Acknowledgments

CHR is employee of Glycom A/S a company developing the human high-purity form of sialic acid (NANA) for food applications including infant formula. SSHC and NB are employees of Intertek Scientific & Regulatory Consultancy providing Scientific and Regulatory consultancy to Glycom A/S.

Disclosure statement

This review was mainly written by CHR with support and collaboration of the other authors.