Archaea, Bacteria, Fungi Oh My!

What if I told you that there were trillions, yes trillions, of tiny microorganisms living in/on you all the time? From fungi to bacteria to viruses, the human body is literally filled with these microscopic organisms. We tend to think of microbes as pathogenic or as germs that are bad for our health, but if that were the case then why are we not always sick if there are trillions of microbes living in and on us at all times? The answer is that these organisms are actually extremely important for our health and well-being. Disruptions to the human microbiome can yield extremely detrimental effects as a result of the mutualistic symbiotic relationships that exist between humans and these various microorganisms. Disrupting the normal balance of microbiota in the body opens the door for not so friendly microorganisms to take their place.

So we’ve established that the microbiome has an overall mutualistic relationship with the human body, but what exactly do these microbes DO for us? On our end, we provide nutrients and a relatively safe or favorable environment for them to grow and divide, but what benefits can we gain from bacteria living in our body? In general, the human microbiome plays a significant role in regulating our metabolism, specifically our glucose metabolism, by using excess glucose as their own energy sources, as well as by synthesizing different nutrients that humans cannot synthesize on our own, such as Vitamin B. We also know that the microbiome changes significantly as we develop. An article in Cell dives deep into the evolution of the human microbiome throughout life. Early on, our microbiome is extremely limited, however it quickly develops and can be influenced by several external factors, making the period immediately following birth absolutely critical to developing a healthy microbiome. For example, breast feeding can have a significant impact on the composition of the microbiome, with more favorable microbes for digesting and breaking down breast milk components being selected for in the child. Over time, the microbiota of the gut diversify to find ecological niches within the gut, specializing in breaking down specific substrates and producing certain byproducts based on the nutrients available to them. Clearly, proper development and diversification of the human and gut microbiome are critical for healthy digestion and nutrient acquisition purposes. As such, diet is a huge factor in microbiome development and overall health.

Since the human microbiome is so influential and important in promoting overall health, what happens when theres an imbalance or error in the microbiome (aka dysbiosis)? First off, imbalances have the potential of opening the door for pathogenic microbes to infiltrate the gut and disrupt the homeostatic state of the gut and body as a whole. For example, Clostridioides dificile is a bacterium that takes advantage of dysbiosis of the gut to enter the large intestine and synthesize toxins that destroy/kill the epithelial cells and prevent proper absorption of nutrients. This bacterium causes formation of pseudomembranes in the large intestine and results in diarrhea as well. An article published in PLOS in October examined the influence of the gut microbiome on the brain-gut axis and sleep quality. They found a positive correlation between sleep efficiency and gut microbial health. It was also found that more diverse microbiomes were associated with sleep factors that indicate greater levels of cognition. This article further discusses how microbiota transplant surgeries have been demonstrated to improve irregular sleep conditions such as epilepsy and have even been able to alter behavior in those diagnosed with Autism Spectrum Disorder. The study demonstrates the influence of the microbiome on the brain-gut axis and how the brain-gut axis has a diverse and wide range of influence on behavior, cognition, etc. At least for me, these findings represent a huge window of opportunity for future study as we learn more about the relationship of the human microbiome and the brain-gut axis. Who knows what we could accomplish by carefully altering the human microbiome, specifically that of the gut, to treat all kinds of diseases? The opportunities seem endless seeing as epilepsy and autism have already been shown to be linked to the brain gut axis and the health of the microbiome. If you needed any more of a reason to change your diet to a healthy one, look no further than the human microbiome and its influence over the mind and body.