Sialic acid (SA) is a naturally occurring derivative of nine-carbon monosaccharides that are typically present as oligosaccharides, glycoproteins, or glycolipids in the blood during pregnancy and in breast milk. Hepatic synthesis of SA occurs from the fetal period to 6 months after birth; therefore, exogenous SA is essential for early life growth and development. This review examines the nutritional requirements for various forms of SA in early life, considering its content in the maternal serum, breast milk, and supplementary infant foods. Additionally, it examines the synthesis and metabolism of SA, its roles in the brain and intestinal development, immune system maturation, and its efficacy in preventing and managing preterm birth and related conditions. Finally, it highlights crucial research in SA nutrition in early life to provide a scientific basis for the use of SA in infant formulas, maternal food, and medical settings.

The stability of powdered formulae for young children of different age groups packaged in atmospheres with different residual oxygen levels (0.2%, 2%, 3% and 5%, V/V) was investigated, and the effect of residual oxygen levels inside the package on the nutritional value and flavor of young child formulae was evaluated. The results showed that during accelerated storage for 24 weeks at 37 ℃ and relative humidity of 75%, the nutritional and sensory characteristics of young child formulae were susceptible to the residual oxygen inside the package. With the increase of residual oxygen inside the package, the content of VA, VE, VC and lutein decreased generally, while the content of all volatile lipid oxidation products except propanal increased, and the content of propanal in young child formula with a residual oxygen percentage of 3% inside the package was the highest. Therefore, the residual oxygen inside the package is crucial to the quality of young child formula, and low levels of residual oxygen are conducive to the stability of young child formula during storage.