In this present posting I want to slightly explain about prebiotics in human breast milk. First of all, we should prior understand about the term of prebiotic. The term prebiotic applies to all those substances which are contained in food and resist stomach acid environment, the action of the biliary salts and digestive enzyme degradation; then they reach the colon and selectively stimulate the development and activity of the Bifidobacteria and Lactobacilli, with beneficial effects on the host’s health.
In normal conditions the human gastrointestinal tract at birth is sterile. At the beginning, the development of intestinal microflora is modulated by several extrinsic factors such as the type of birth, the environmental contamination, sanitary conditions and the geographical distribution of bacterial species. Afterwards, the main factor conditioning the development of the newborn’s intestinal ecosystem is generally represented by the type of feeding. The intestinal microflora of the breast-fed infant is represented up to 90% by bifidobacteria and lactobacilli, whereas in the bottle-fed newborn these two genera of microflora represent only 40-60% of the intestinal flora, with the remaining composed of Enterobacteriaceae and Bacterioides.
Many research proved that there are several beneficial effects of a microflora dominated by bifidobacteria in breast-fed babies, including inhibition of the growth of pathogenic microorganisms, modulation of mucosal physiology, barrier function and systemic immunologic and inflammatory responses. The peculiar composition of the intestinal microflora of breast-fed newborn is certainly due to the presence in human milk of particular substances with prebiotic effect. On the contrary, those substances are not present in the cow’s milk used to prepare infant formulas. In human breast milk, a prebiotic effect has been ascribed to a low concentration of proteins and phosphorus, the presence of lactoferrin, lactose, nucleotides and oligosaccharides. According to the several references, oligosaccharides seem represent the main substances among the others that able to promote a bifidobacteria-dominant microflora in baby since proteins and phosphorus, lactoferrin, lactose and also nucleotides didn’t show any relevant data in showing of influence on the intestinal microflora composition.
There is abundant literature supporting the prebiotic effect of oligosaccharides. The oligosaccharides are carbohydrates composed of 3-10 monosaccharide units and are the third major component of breast milk from a quantitative point of view, after lactose and lipids. According to Montreuil, oligosaccharides achieve maximum concentration in the colostrums (above 20 g/L) and, after a couple of weeks, they reach stability, i.e. about 12−14 g/L in mature milk. On the contrary, cow’s milk, used to prepare artificial formulas, has a content of oligosaccharides of less than 1 g/L. And also, oligosaccharides resist the digestion and able to reach colon where they stimulate the development of “good bacteria” (which dominantly occupied by bifidobacteria), thus representing the paradigm of prebiotics.
No natural substance has the same biochemical composition as human milk oligosaccharides, and these cannot be synthesized in large quantities and at acceptable cost. For this reason the industry has been focusing on the production of carbohydrates which, though they have a different composition, can stimulate the growth of bifidobacteria and lactobacilli in the colon, thus reproducing the prebiotic effect of human milk oligosaccharides. In particular, galacto-oligosaccharides (GOS), fructo-oligosaccharides (FOS) and inulin have been used as non-digestible oligosaccharides in the supplementation of infant formulas. Until today several studies have been carried out using a mixture of non-digestible oligosaccharides (FOS, GOS, and inulin) in newborns (preterm and full-term) and in infants. The result showed a significant dose dependent increase in the number of bifidobacteria, whose concentration in the faeces was comparable with that of breast-fed babies. These results confirm the important role of oligosaccharides as prebiotics.
In conclusion, it clearly emerges that oligosaccharides (prebiotics) undoubtedly represent the main substances that able to stimulate the development of intestinal microflora in our beloved baby.
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