Babies in industrialized countries are losing a species of gut bacteria that digest breast milk
Newborns’ guts are nearly sterile at birth, but they become a community of trillions of microbial cells, known as the microbiome, by the time they reach adulthood. Because breastfed babiesTheir health has a solid start with milk providing nutrients for good bacteria that fight pathogens.
However, according to a study led by researchers at Stanford Medicine, bacteria that are effective in digesting breast milk are being lost as countries industrialize. Because no other bacteria are so adept at digesting milk, the researchers fear this bacterial migration could mean an increase in cases of diseases common in the industrialized world, such as such as chronic inflammation.
Research shows that bacteria from the genus Bifidobacterium – bacteria that live well in the gut – are the most common species in the microbiome of infants under 6 months of age around the world – regardless of whether they are breastfed or formula fed. . Researchers discovered that a species called Bifidobacterium Infantis (or B. Infantis) – is known to effectively break down a particular type of breast milk sugar called oligosaccharides, as well as strengthen the immune system. Immunity and microbiome development – dominating the infant gut microbiota in de-industrialized societies.
In contrast, Bifidobacterium breve, a species with a very limited ability to break down milk sugars, was the most common among infants in industrialized countries.
The new one researchpublished in the magazine Science, found that although breastfeeding increased the number of effective bacterial species in industrialized countries, it was still much lower than in unindustrialized countries. The researchers speculate that in the absence of B. infantis, breast milk may have a limited ability to promote all of the benefits for the infant, both in terms of microbiome development and health. of infants.
“The extraordinary property of the gut microbiome is that it is malleable,” said lead author of the study. Justin Sonnenburg, Ph.D., a professor of microbiology and immunology. “Because of this malleability, the gut microbiome can deteriorate. This has happened in industrialized nations over the past century.”
The researchers used 62 stool samples collected over a year to study the infant gut bacteria of the Hadza, a hunter-gatherer people in Tanzania, comparing them with 17 other populations around the world. – includes communities in Africa, Asia, North and South. Americas and Europe – using DNA sequencing. This method identifies individual species from a sample.
Uncovering the diversity of the gut is underrepresented
Tanzania’s Hadza, one of the last surviving full-time hunter-gatherer groups, has one of the least industrialized lifestyles in the world. The abundant gut microbiota of unindustrialized people is important for understanding the true capabilities of the gut, but it has not been well studied, says Sonnenburg.
According to Sonnenburg, several factors have led to low gut diversity in industrialized countries: cesarean section, antibiotics, hygiene, and a diet high in saturated fat, low in fiber, as well as sweeteners. and high artificial emulsifier. C-sections, he adds, prevent the sharing of important bacteria in the vagina and infant formula with altered gut microbiota early in life.
The number of microbial genes in the human microbiome is 100 times greater than the number of human genes in the human genome: about 2 to 10 million genes. Because of the large number, the researchers used deep genomic sequencing to study the genomes of species in the microbial community. This method provides insight into the viability of all microorganisms.
Sequencing has yielded a diversity not seen before in industrialized countries: 23.4% of the microbial species detected in newborn Hadza were new species not found in the traditional human digestive system. A catalog of all the bacteria detected in the human gut microbiota.
“We have unlocked this store of diverse gut data that will forever change the way we understand infant gut bacteria and their role in the human microbiome,” said Matthew Olmlead author of the study and a postdoctoral scholar at Sonnenburg’s laboratory.
This novelty provides background information for studying central functions of the infant gut microbiota development, including functions that are being lost in industrialized populations.
Microbial balance to support immune health
The team was particularly interested in the milk-digesting genes of Bifidobacterium because their absence could have long-term immunological consequences.
Milk sugars, known as oligosaccharides in breast milk, feed and recruit beneficial bacteria, especially B. infantis, which is the base species for building a healthy infant’s gut microbiome. born. According to Sonnenburg, many of the complications common in the industrialized world, such as allergies and asthma, are thought to be the result of an imbalance in the microbiome.
Sonnenburg says that cataloging variation in the human gut microbiota around the world could help clinicians diagnose the cause of disease and tailor a patient’s microbiome to improve the health of their patients. improve symptoms – what he calls precision health.
“If you change the gut microbiome, changes happen in the human body,” says Sonnenburg. “The same associations between the gut microbiome and all types of chronic inflammatory diseases – from metabolic syndrome to heart disease, different types of cancer to autoimmune disease – also hold potential.” Leveraging these connections for precise health and ultimately disease prevention.”
The effects on the immune system of small amounts of B. Infantis, which infants usually inherit from their mothers during birth and through breast milk, are largely unknown. However, a study by the University of Nebraska suggestions Deficiency of B. Infantis leads to systemic inflammation and immune dysregulation in early life. Interventional studies, like a clinical research of Sonnenburg, have shown the reintroduced species of B. Infantis and the discovery that malnourished children gain weight is attracting the interest of scientists like Sonnenburg.
Sonnenburg wants to see more studies of microbiome diversity in unindustrialized populations, so he can learn more about interventions and understand the health implications of a The microbiome is changing.
“The gut microbiome is the driving force behind many functions within us,” says Sonnenburg. “Our gut microbiome is evolving and we need to understand what it means to lose bacteria that can be important components of human biology.”
Source: Stanford University
