Is glycogen an important constituent of human milk?

Human milk stands as the optimal natural source of nutrition for infants, harboring a plethora of complex nutrients including water, carbohydrates, lipids, minerals, proteins, and vitamins, as well as a diverse array of bioactive molecules such as oligosaccharides and growth factors, etc. These components facilitate and safeguard the growth and development of infants. Furthermore, the composition and concentration of human milk subtly evolve across different stages of breastfeeding, adapting to the specific requirements of infants. Therefore, attaining a more precise and comprehensive understanding of human milk composition holds significant value. In this study, a succinct overview of the primary constituents of human milk and their fluctuations during various lactation periods was provided. Then, existing research is critically examined concerning the existence of free glycogen in raw human milk because previous studies indicate the presence of glycogen in human milk but do not determine whether glycogen exists in free form. Glycogen within human milk may exert influence on the growth, development, and establishment of the immune system in infants, but precise mechanisms must be determined. Elucidation of the existing form of glycogen particles in human milk will not only update our understanding of human milk composition, but will also strengthen the roles of glycogen in infant development. Through our exploration, the presence of free glycogen in human milk appears plausible. However, further experiments are needed to confirm the claim via solid evidence.