Prebiotics In Breast Milk: How Do They Work? – Being Parents

Prebiotics are known to be the compounds of a soluble fiber which, when ingested, cannot be digested as they pass through the upper gastrointestinal tract.

As a result, when the prebiotics reach the large intestine, the resident bacteria that can process this fiber use them as an energy source. The prebiotics then stimulate the growth of foci of colonial bacteria.

We must not confuse prebiotics and probiotics

Their names suggest it: prebiotics and probiotics are related. However, it is important to understand how they differ. By definition,  probiotics are living microorganisms that have a positive influence on health. Among them we identify lactobacilli and bifidobacteria (both of which are part of the group of bacteria called acid-lactic acid) and saccharomyces (a genus of yeast).

Also,  prebiotics are not bacteria. These are compounds provided by the food source for the probiotics to live and proliferate in their niche, the colon. Prebiotics are substances that act as food for probiotic organisms.

Why are the bacteria that reside in our gut so important?

First of all, because there are so many of them. Bacteria make up most of the flora in the colon; they represent more than half of the dry mass of the stool.

In addition, their composition is very variable. The intestinal flora is made up of more than a billion species. In each person there is a numerical predominance of about 30 or 40 species.

This immense quantity of microorganisms creates an ecosystem that is extraordinarily mature and resistant to changes from outside. This balance has the medical name of “intestinal homeostasis”.

Exposure to antibiotics, enteric infections, or dietary changes can alter this homeostasis. Evidence also links  the imbalance of the intestinal flora to a long list of diseases. To restore this balance, prebiotics and probiotics are therefore ingested and, in the most serious cases, fecal transplants are carried out.

The content of breast milk is rich in prebiotics and probiotics

Currently, science recognizes that breast milk is irreplaceable as a factor in the initiation, development and composition of the baby’s intestinal flora.

This information is not yet widespread, but  breast milk contains a large number of lactic acid bacteria that the mother “gives” to her baby, to start colonization of the intestine. It is estimated that the infant ingests approximately 800 ml of milk per day. It then receives between 100,000 and 100,000,000 bacteria daily.

In addition to this,  the mammary glands can produce an extraordinary repertoire of prebiotic compounds. They are called oligosaccharides. Ingesting probiotics and prebiotics together is nature’s winning strategy for getting “good bacteria” to colonize the infant’s gut.

The carbohydrates in milk can be made up of a single sugar molecule: monosaccharides. For example, glucose, galactose and fructose. Oligosaccharides consist of five types of monosaccharides combining at random to form linear structures or with branches of varying size.

Surprising data on prebiotics in breast milk

The proliferating effect of milk on lactic acid bacteria is not linked to a single substance: it obeys different factors. More particularly,  the prebiotic effect of milk has been attributed to the low concentration of proteins and phosphates  and the presence of lactoferrin, lactose, nucleotides and oligosaccharides.

The actual prebiotic role of each of these substances is not yet clearly defined, with the exception of oligosaccharides, which is the most studied group.

It is not yet clear why the huge repertoire of oligosaccharides varies from woman to woman and, in the same woman, from one breastfeeding stage to another. It is estimated that  the approximate number of oligosaccharides can vary from 150 to 100,000 compounds. Within this universe, we know that there is a predominance of the galacto-oligosaccharide (GOS) series.

Additional functions of breast milk oligosaccharides

The repertoire of oligosaccharides in milk is unmistakable. Various studies have shown that these compounds can perform different functions:

• They can fool pathogenic viruses and bacteria. Some variants emulate the oligosaccharides in the intestinal wall, more specifically those used by pathogens to invade healthy cells. When the pathogen unites with this decoy, infection is avoided.
• They can also regulate the activation of immune cells.