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Member of the SEM (Spanish Society of Microbiology) and Full Professor of Microbiology, University of Navarra.
We have known for years that breast milk is not sterile. Hundreds of different bacterial species have been identified in the colostrum and milk of healthy mothers, which normally end up in the digestive system of their offspring.
As a consequence, the microbiota is different depending on whether babies are breastfed or bottle-fed. The microbiota of the former is rich in Bifidobacteria and Lactobacilli, while bottle-fed babies have a more diverse bacterial community with an abundance of Escherichia coli, Clostridium and Bacteroides.
In addition, it has been shown that the bacteria isolated from the mother's milk and the baby's feces are similar. About 30% of the bacteria that colonize the baby's gut during the first months of life come from breast milk and another 10% from the mother's skin, specifically from the skin around the nipple.
Well, one of the ubiquitous bacteria in breast milk, Akkermansia muciniphila, has such beneficial effects on health that it could become a new food if it can be produced on an industrial scale.
The first probiotic and the first prebiotic
Breast milk is therefore the first probiotic we take in our life. And since financial aid also feeds the baby's own microorganisms, it simultaneously acts as a true prebiotic.
Among the most abundant components of breast milk are oligosaccharides, molecules composed of a few sugars that babies cannot digest at first. So what are they good for? Very simple: they increase the population of Bifidobacteria in the baby's intestine and are predominant during the first four months of life. Some of these Bifidobacteria have specific and unique enzymes, capable of breaking down those sugars in breast milk and using them as a nutrient. And the same happens with Akkermansia, some of these oligosaccharides are very similar to those that constitute mucin, the main nutrient of this bacterium. Hence their importance.
But there is more: these oligosaccharides also act as antimicrobial anti-adhesives that prevent pathogenic microbes such as Streptococcus pneumoniae from binding to the mucosal surface of the baby's intestine. This reduces the risk of infection. Breastfeeding also protects against the development of diarrhea and enterocolitis in the newborn and has been associated with a reduced risk of intestinal inflammation.
The symbiotic relationship between the baby's microbes and the composition of the mother's milk seems undeniable. And the two have evolved together over millions of years to make the baby healthier, especially by strengthening its defenses. Exciting!
Akkermansia muciniphila, a "good" bacterium
Akkermansia muciniphila is a strict anaerobic Gram-negative bacterium that is part of the natural microbiota in healthy people. It was first isolated in 2004 from human stool samples, although it is not unique to our species.
The name Akkermansia honors the Dutch microbiologist Antoon Akkermans, in recognition of his contribution to microbial ecology. Muciniphila (which is the species) means "mucus-loving", as this bacterium feeds almost exclusively on the mucus that lines the intestine. This is where it is most abundant, mainly in the large intestine, although it also inhabits the oral cavity, pancreas, bile ducts, gall bladder and appendix. It is a commensal bacterium, it is part of the natural microbiota in healthy people. It represents up to 4% of the total fecal microbiota from the first years of life until we are old, it has been isolated even in samples from centenarian individuals.
Akkermansia muciniphila produces short-chain fatty acids that may play an important role in the health and inflammatory status of the host. This bacterium also appears to be associated with increased intestinal mucosal thickness, which improves intestinal barrier function. In addition, other programs of study have revealed its anti-inflammatory role in the intestinal environment. On the other hand, the beneficial effects of _ A. muciniphila_ have been demonstrated in different programs of study, such as a protective role against pathogens, antitumor properties, reduction of inflammation, improvement of intestinal permeability and enhancement of the immune response. All this could explain why the presence of A. muciniphila has been associated with a healthy gut.
On the contrary, its scarcity could favor several pathological conditions, such as ulcerative colitis and Chron's disease. People with acute appendicitis also have a reduced amount of this bacterium, the more severe the appendicitis, the lower the amount. And something similar occurs with obesity, fatty liver disease and diabetes. Alterations in the presence and abundance of this bacterium have also been associated with hypertension, inflammation, epilepsy, metabolic problems, autism, amyotrophic lateral sclerosis, cancer, psoriasis, allergic diseases, parkinson, etc.
Interestingly, pasteurized bacteria, but also proteins isolated from the outer membrane of the bacterium, are more efficient than viable live bacteria in alleviating these health problems. Therefore, bacterial products made from A. muciniphila or the proteins it secretes could become new therapeutic tools against chronic metabolic and inflammatory diseases.
The food bacterium
In September 2021, pasteurized Akkermansia muciniphila became the first bacteria approved as a food by the European Food Safety Authority. It is not actually a probiotic, as the bacterium is not administered live, but dead, pasteurized.
The traditional way to cultivate this bacterium in the laboratory is the brain and heart infusion broth supplemented with porcine mucin under anaerobic conditions. The way to obtain large quantities of the bacteria for the preparation of this "food" seems to be an "industrial secret" for the time being.
Although new clinical programs of study are needed to confirm its beneficial effect on health and to understand the molecular mechanisms behind it, Akkermansia muciniphila is a good example of those beneficial gut bacteria from which we have much to learn.