Breast milk is the best food for newborns. Breast milk naturally contains various nutrients suitable for the digestion and absorption of infants, such as protein, fat, carbohydrates, various minerals and vitamins and other trace elements. In addition, breast milk also contains a variety of bioactive substances suitable for infants, such as lactoferrin, immunoglobulin, human milk oligosaccharides, probiotics, etc., which play an important role in the health of infants. Human milk oligosaccharides (HMOs) are the third most common solid component in human breast milk, second only to lactose and fat, which have important biological functions and not only play an anti-infective role against intestinal pathogenic microorganisms, but also maintain the balance of intestinal microecology.

Introduction to HMOs

Oligosaccharides, refer to a class of oligosaccharides linked by three to ten monosaccharide units through glycosidic bonds to form straight or branched chains. Its molecular general formula can be generally expressed as (C6H10O5) n, with n ranging from 3 to 10. Sweetness is generally only 30% to 60% of sucrose and is difficult to digest and absorb by the intestine. HMO accounted for 24% of total colostrum compounds at higher levels in colostrum. During the first 2 months of life, the concentration steadily decreased to 15% to 19%. The type, quantity and charge of HMO in the milk of different individuals are different; in the same individual, the HMO content in the milk also varies at different stages of lactation.

Physiological Functions of HMOs

Defense against infection

The pathogenesis of pathogenic microorganisms has commonalities: first, they bind to the cell surface they want to invade, then invade the cells, release toxins and take up nutrients, and lead to a series of clinical symptoms. The binding of the first step has been shown to be accomplished by the binding of pathogenic microorganisms or toxins to intestinal epithelial cell surface receptors through their surface sugar chain ends. HMO components function to directly block receptors on the surface of intestinal epithelial cells.

Function of maintaining intestinal microecological balance

HMOs are not destroyed by gastric acid and decomposed by digestive enzymes in the human body, can directly reach the large intestine, stimulate the growth of beneficial flora (bifidobacteria and lactobacilli) in the intestine, indirectly inhibit the growth of harmful bacteria, and maintain the intestinal microecological balance, therefore, HMOs are regarded as the first probiotics in humans. Compared with common formula feeding, the number of bifidobacteria in the intestine of infants with the former was significantly increased, because breast milk contained a large number of oligosaccharides.

Regulatory Functions on the Immune System

Researchers concluded that HMO can indirectly affect non-specific immune responses in humans, and its antigenic determinants have an irreplaceable role in immune system information transmission and immune coordination. The intestine is the largest immune organ of the human body and has 70% of the immune cells of the human body. Bifidobacterium can stimulate the intestine to produce immune substances and antibodies and enhance cell activity, thereby improving the body's immunity to pathogens and tumors.

Promoting function for early development of neonatal brain

High concentrations of sialic acid were adhered to some HMO ends in breast milk. Sialic acid is involved in the composition of gangliosides and glycoproteins in human brain tissue and is closely related to synapses and nerve conduction, so breastfeeding helps to enhance neuritogenesis and promote infant nervous system development.