Our body is made out of more bacteria than cells and the variety of genes in the gut is vastly greater than the human genome. Our second brain (bacteria in the gut) weighs more than 1kg which, is equivalent to the whole brain. It is no surprise that the vast majority of our physiology and brain function are closely linked to our gut microbiota.
The human gut is sterile from bacteria before birth and the first encounter occurs during birth through the birth canal as it gets colonised via the mouth, skin, gastrointestinal tract and conjunctiva. Several bacterias are to be transmitted via the mother to the newborn including Bifidobacterium, Prevotella and Lactobacillus via vaginal delivery and Staphylococcus, Corynebacterium via C. section.
The microbiota of each individual is unique just like their DNA. Our microbiome colonization begins at birth and continues through early life. However, the composition, diversity and function of each person’s microbiome are altered by mode of delivery, formula/ breastfed, medications, antibiotics and other environmental factors which influences the microbe-host interactions and the individual’s physiological developments.
Another factor which the gut microbiota plays a crucial role is its iterations with our brain. Numerous studies have shown that there is a bidirectional link between depression and gut microbiota which, indicates its link to dysregulation of the Hypothalamus Pituitary Adrenal (HPA) axis. The imbalance to HPA axis is triggered by activation of cytokines (interleukins 1 and 6) which are responsible for the stimulation of cortisol (stress hormone). Moreover, Cortisol has shown to affect gut microbiota by altering the gut PH and increasing gut permeability.
Our gut is the home to our ultimate happiness. Gut bacteria are responsible for the production of hundreds of neurochemicals which our brain uses for regulating the day to day processes such as memory, mood and learning. Our gut manufactures 95% of the body’s serotonin.
Serotonin is mainly responsible for
• regulating mood and social behaviour
• appetite
• digestion
• sleep
• memory
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