Where the microbiome comes from
From the onset of life, the impact of the microbiome is evident. Divergent fecal microbiota compositions are observed in infants delivered via C-section versus those born through the vaginal route, potentially leading to disparate health outcomes. Studies indicate that the fecal microbiota of infants delivered vaginally tends to be similar to that of their mothers over time, while C-section-delivered children exhibit dissimilar compositions.
Infants delivered vaginally maintain a relatively stable gut microbiota composition profile throughout the first year, marked by an abundance of Bifidobacterium species and a reduction in potentially harmful Enterococcus and Klebsiella species. Conversely, the gut microbiota associated with C-section delivery at one week of life may predispose infants to respiratory infections in the initial year, irrespective of intrapartum antibiotic use.
The choice between breastfeeding and formula feeding also marks a divergence, as breast milk, rich in oligosaccharides, nourishes beneficial bacteria like Bifidobacterium, profoundly shaping the infant's gut microbiome. As babies transition from milk to solid foods, their microbiome experiences significant changes, progressively adopting characteristics similar to those found in adults. Microbes are shared and exchanged between family members, contributing to this transformation. This microbial sharing is most pronounced during infancy and gradually becomes more diverse as the child ages and encounters various environments and dietary patterns.
Pets also contribute to this microbial exchange, with studies showing that infants living in homes with cats or dogs harbor a more diverse microbiome. This suggests that exposure to various microbes in early childhood may protect against allergies and asthma and potentially boost health.
A 2016 study, which looked at the early life experiences of 10,000 adults in 14 countries in Europe, Scandinavia, and Australia, found that children who had lived on a farm between birth and age five were 54 percent less likely to have asthma or hay fever as adults than children who had grown up in inner city areas. Additionally, they were 57 percent less likely to have allergic nasal symptoms.
Young people, young guts?
As we age, changes occur in the composition of microorganisms within our digestive system. There is a decline in beneficial species like Faecalibacterium, known for its anti-inflammatory properties, while species contributing to inflammation become more prevalent. This shift in gut microbes is associated with various age-related conditions, including heart disease, cancer, and cognitive decline.
A 2021 animal study supports this notion. Researchers observed that transplanting the microbiota of young mice into the intestines of older mice resulted in enhanced cognitive function in the older mice. This underscores the connection between the transfer of a gut microbiome from a younger mouse to an older one and the subsequent improvement in cognitive abilities in the older mice. Mice are commonly employed as model organisms for studying human biology.
The microbiome is not a mere passenger in our bodies but plays a crucial role in our health and well-being. From influencing our mood and dietary choices to determining our susceptibility to certain diseases, these microscopic inhabitants are central to understanding our biological existence. As scientists continue to unravel the complexities of the microbiome and its far-reaching implications, we are challenged to redefine our perception of humanity, recognizing the indispensable role of these microscopic life forms in our lives.
New Scientists: Myths about the microbiome abound – but the truth is more interesting
Gut Microbiota for Health: Scientists find a link between delivery mode and susceptibility to respiratory infections in the first year of life, regardless of maternal antibiotics
New Scientists: Where does your gut microbiome really come from - and does it matter?
New Scientists: How your microbiome is shaped by your friends, family, lovers and pets
The University of Melbourne: Kids on farms have lower allergy risks, stronger lungs as adults
New Scientists: The best way to care for your microbiome to keep it healthy as you age
Nutrients: The Interplay between the Gut Microbiome and the Immune System in the Context of Infectious Diseases throughout Life and the Role of Nutrition in Optimizing Treatment Strategies
New Scientists: Can probiotics and supplements really improve your gut microbiome?
ScienceDirect: Lactobacillus rhamnosus
Nature Communications: The genomic landscape of reference genomes of cultivated human gut bacteria
Enzyme and Microbial Technology: Probiotic characteristics of Lactobacillus gasseri TF08-1: A cholesterol-lowering bacterium, isolated from human gut