If we haven’t realized as yet, this post will help you realize, Nature is so very intelligent and that we need to be in HARMONY with nature to survive and thrive.
Human body has vast numbers of commensal bacteria, viruses and fungi collectively known as Gut Microbiota or Gut Microbiome. An average human body has more than 100 TRILLION microbes and outnumber human cells. Let dig deep into understanding their role and why GUT MICROBIOTA is critically important to our survival and evolution.
Human-associated microbiota are communities of bacteria, fungi, and viruses (often referred to as the bacteriome, mycobiome, and virome respectively) that live on and/or inside the human body.
Microbial communities exist on every mucosal surface in the human body, and each body site within a person presents a unique ecology. Each individual’s human-associated microbial community is unique compared to that of all other humans.
Human-resident microorganisms encode an estimated 2 to 20 million genes, whereas the human genome encodes an estimated 20 to 25 thousand; therefore, the microbiome represent up to 99.9% of the genetic capacity in the human body.
During each stage of life from birth to death and decomposition, microbial communities act as a dynamic component of the body. Thus investigating the natural and induced changes in our microbiota has the potential to revolutionize our understanding of human biology.
BIRTH – Type of Birth either Natural or Assisted determines your microbiota
The first factors that shape a human microbiome come from the mother during fetal development. The fetus is exposed to metabolites produced by the mother’s microbial community through the placenta, which imprint its immune system and can affect both the normal microbiome and also various aspects of pathology later in life.
The composition and transfer of these metabolites to the fetus can be impacted by the mother’s health, diet, and use of antibiotics during pregnancy. For example, the mother’s gut microbiota ferments dietary fiber resulting in short-chain fatty acids (SCFAs) such as acetate which have been observed to cross the placenta.
Acetate in the fetal tissue affects epigenetic imprinting linked to the generation of regulatory T cells (Tregs) in adults, which is associated with protection from the development of asthma later in life.
Important Fact for Pregnants – Maternal antibiotic use and gastrointestinal-related diseases such as inflammatory bowel disease (IBD) are also thought to increase the risk of pathology in offspring later in life by imprinting of the fetal immune system.
The beginning of the human microbial community and the start of primary succession occur at birth with the seeding of the infant from the mother’s microbiota.
The development of the bacterial community in the human gut has been well studied. Bifidobacterium spp. are dominant until they give way to a combination of Bifidobacterium, Clostridium, and Bacteroides spp. by the end of the first year one of life. This is followed by a greater increase in Bacteroides spp., a more diverse set of genera within the phylum Firmicutes, and a relative decrease in species such as those in the genus Bifidobacterium.
Bifidobacterium spp. catabolize human milk oligosaccharides (HMOs) from the mother’s breast milk, which is believed to begin imprinting the immune systems for life. Most recently, a study found functional links between bacteria such as Bifidobacterium spp. containing genes required for catabolism of HMOs and the infant immune development.
Type of Birth – Natural v/s C-Section
Several factors shape and differentiate microbial community development in the first few years of life. Birth mode and maternal antibiotic use are among the best-studied and clearest factors that influence the human microbial community.
The process of natural microbial community establishment can be disrupted, in all body sites, through caesarean section and perinatal and neonatal antibiotics. A number of studies have demonstrated that infants born vaginally had higher relative abundance of Bacteroides spp. than those born by C-section.
Adult Age – Microbiota Development
Although the adult microbial community is largely stable compared to the big changes that occur during primary succession in infancy, the community can be perturbed and pushed away from the climax community state. The understanding of the microbiome during health and disease is a deepening and disease-specific research field.
The large influence of diet in shaping the microbiome may also play a role in human health, and much work is being dedicated to understanding how specific dietary components, and dietary patterns overall, influence the microbiome and its impact on health.
Aging due to both biological programming and accumulation of damage throughout life impacts every aspect of cellular function, and the microbiome is no exception.
With advanced age, the gut microbiota alpha diversity decreases and the beta diversity (variation between individuals) increases. Much is still unknown about the microbiota in old age, but the community succession observed in the gut is a decrease in bacterial genera dominant and prevalent in younger adults, such as Bifidobacteria, Bacteroides, and Lactobacillus, often with a decrease in the ability to fend off blooms of opportunistic bacteria such as Enterobacteriaceae and Clostridium spp.
Skin bacteria of the genera Cutibacterium (formerly, Propionibacterium) and Staphylococcus decrease in older age with a greater abundance of Corynebacterium being observed. In the oral body site, Rothia and Streptococcus spp. dominate the core oral bacterial community, with consistent decreases in Porphyromonas, Treponema, and Faecalibacterium spp.
The gut mycobiome in old age is characterized by an increased dominance of Penicillium, Candida, Aspergillus, and Saccharomyces spp. In the skin and oral body sites, very few studies exist, but old age is characterized by a decreased abundance of Malassezia spp. in the skin and Candida spp. in the oral cavity.
In gut phages, Siphoviridae dominance in adulthood gives way to Microviridae, Podoviridae, and crAssphages in old age. Contrary to gut bacteria, fungi, and phage populations, eukaryotic viral diversity stays constant after childhood throughout the rest of life.
Due to the high variability between individuals, the focus of research into microbial succession in old age has primarily been in the comparison of healthy and unhealthy aging. It remains unclear if the microbiome has a mechanistic role in healthy aging or is just a strong indicator of other variables, such as diet, exercise, and medications. However, in those who live longer and healthily, commonalities can be observed in sustained retention of those taxa highly prevalent in healthy adults such as Bacteroides spp.
However, centenarians exhibit a more unique microbiome with increased alpha and beta diversity, complicating the comparison between ‘healthy’ and ‘unhealthy’ aging. Although promising, this area of research is still underpowered and emerging.
Home foods shaping Gut Microbiota
Communities through millennia have realized the importance of Gut Microbiome as well as diet which influences / shapes the human microbiota. That’s why many communities have dishes such as kimchi, kombucha, home made curds, pickles and sourdough. Take care of your Gut and it takes care of you, that is the essence of Human Gut Microbiome.
