Review on bioproduction of sialylated human milk oligosaccharides: Synthesis methods, physiologic functions, and applications

Human milk oligosaccharides (HMOs) are crucial for promoting neonatal health, with sialylated oligosaccharides, a significant subclass, offering a variety of health benefits such as prebiotic effects, anti-inflammatory and antimicrobial properties, antiviral defense, and cognitive development support. Among these, 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL) have received "GRAS" status from the U.S. Food and Drug Administration and approval from the European Food Safety Authority for use as novel food additives in infant formula and supplements. This review focuses on the synthesis methods of sialylated human milk oligosaccharides (SHMOs), their functional properties, downstreaming developments and application technologies. Given the challenges associated with achieving sufficient availability for food and medical applications, the review emphasizes the viability and efficiency of various production strategies. The review also highlights recent research advancements and offers insights for optimizing large-scale production to support future applications in the food and pharmaceutical industries.