Author: Hanah Gomberg
Editors: Lydia Ren and Cynthia Zhang
Artist: Nicole Tseng
Most of our bodies are not cells containing the genetic material that makes us who we are, but instead, microbes make up most of our being. While this may be somewhat surprising, these microbes are essential for our survival and wellbeing. The human microbiome differs significantly from person to person, and believe it or not, their development might even have a say in our likes, dislikes, and protect us from cancer and other diseases that are detrimental to your health. Since the microbiome has an inevitable impact on our health and well-being, it is important to discuss misconceptions that often cause the unfair demonization of microbes, how microbes within our bodies interact with the things around them, and how your varying microbes might have meaningful connections with one another.
First of all, you must be wondering what exactly is our microbiota. In our bodies, many microorganisms and bacterias are the most significant part of the foreign organisms we host; single-celled organisms (archaea), viruses, fungi, viruses, and microbes are all part of our bodies. However, our cells are not the most significant part of our body’s makeup; instead, there are about ten times as many microbes in our bodies than our cells. Interestingly enough, our body’s microbiota differs so much between individual to individual that two people living in the same city will have a completely different genome makeup. These little organisms have a disproportionate impact on our lives, health, and preferences. For example, everyone’s bodies respond differently to the same food the microbes we host are believed to have a say on what we like. Professor John Cryan, a neuropharmacologist and microbiome expert from University College Cork, believes that the microbes are “very useful to the body” as they help us breakdown sugar, the foods on our intestines, program the immune system, provide nutrients for our cells and prevent harmful bacteria from attacking us.
Microbiomes also depend on each other to work. For example, the microbes in your gut rely on microbes in your immune system as the metabolites from the intestinal lumen are transported to your lungs, liver, or brain through your bloodstream. This relationship allows for specific immune responses from certain tissues, aiding in cell specialization, which helps us fight diseases much more efficiently. Furthermore, our microbiome is thought to affect the fitness of our body. A recent study revealed that bacterial interactions that shape microbiomes also contribute to our wellness by mapping interactions between bacteria and fruit flies. Finally, the gut microbiome aids us to fight and monitor diseases such as inflammatory disorders, cancer, and depression, thus playing a vital role in maintaining our health.
We have trillions of microbes living in our body. While some can harm us, the vast majority help keep us alive and complete our daily tasks. As you might expect, our microbiome differs significantly throughout our body, as certain microbes can only survive in some areas and are specialized in performing certain functions. An example of this is skin microbes. It is widely known how vital gut microbes are for our health, but the microbes beneath and on our skin are believed to help us fight skin cancer. As aforementioned, these tiny organisms can cause serious health problems; however, they are unfairly demonized as in their vast majority, they help you fight infections and aid in reproductive health. One of the most famous microbiome relationships is the gut-brain axis. It has a vital role in bidirectional connections between the gut and your nervous system. Their relationships help regulate brain function and chemistry, thus alleviating us when responding to stress and anxiety. So how does this relationship work? This is a mutually beneficial connection as the gut produces neuroactive compounds such as serotonin and dopamine to regulate our emotions. In contrast, the brain sends electrical impulses to our digestive system.
The connection between your gut and your brain’s microbiota is a bidirectional neurohumoral transmission system that can boost your overall health. It allows various systems throughout our bodies, including the neral, immune, metabolic, and the HPA axis, to function up to the standard in order to keep us healthy and alive. The microbes in your gut that help form these relationships are commonly named the ‘second brain’ due to its ability to function independently from the brain and spinal cord. This relationship is so beneficial to our bodies that this channel is now being targeted to cure diseases such as Irritable bowel syndrome (IBS). Irritable bowel syndrome used to be linked with a lousy bowel, however, it is now associated with an impact on work and your social life. But why is that, you may ask, as it has seemingly nothing to do with our brain? Recent neuroimaging has found abnormalities in the prefrontal cortex, ventrolateral, and posterior parietal cortex and thalami. The results imply that there would be some alteration in emotion and pain tolerance. Recent studies even suggest that major psychiatric disorders have something to do with IBS. Finally, one of the first symptoms of onset Parkinson’s disease (PD) are problems with your intestines and severe stomach pain, thus proving that this relationship can go either way—unhealthy bacteria on the gut causes brain problems, and vice-versa.
Overall, there is no doubt that microbes and human microbiota are utterly necessary, and primarily, they do a lot more good than harm. Their villainization by our stereotypical beliefs is unfair, as they arguably play the most life-saving roles. Not only do they aid in digesting your food but also assist your immune system and the chemical channels in your brain in communication and firing endorphins. The gut-brain axis helps us diagnose neural and digestive diseases and is now used to help fight a series of diseases.
Citation:
Carabotti, M., Scirocco, A., Maselli, M. A., & Severi, C. (2015). The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Annals of
Gastroenterology, 28(2), 203–209.
Davis, N. (2018a, March 26). The human microbiome: why our microbes could be key to our
health. Retrieved October 7, 2020, https://www.theguardian.com/news/2018/mar/26/the-
Davis, N. (2018b, March 26). The human microbiome: why our microbes could be key to our
health. Retrieved October 7, 2020, https://www.theguardian.com/news/2018/mar/26/the-
Dill-McFarland, K. A., Tang, Z.-Z., Kemis, J. H., Kerby, R. L., Chen, G., Palloni, A., … Herd,
P. (2019). Close social relationships correlate with human gut microbiota composition.
Scientific Reports, 9(1). https://doi.org/10.1038/s41598-018-37298-9
Ding, R., Goh, W.-R., Wu, R., Yue, X., Luo, X., Khine, W. W. T., … Lee, Y.-K. (2019). Revisit
gut microbiota and its impact on human health and disease. Journal of Food and Drug
Analysis, 27(3), 623–631. https://doi.org/10.1016/j.jfda.2018.12.012
González-Arancibia, C., Urrutia-Piñones, J., Javiera Illanes-González, & Bravo, J. A. (2019,
May). Do your gut microbes affect your brain dopamine? Retrieved October 11, 2020 https://www.researchgate.net/publication/333164297_Do_your_gut_microbes_affect_yo
Gould, A. L., Zhang, V., Lamberti, L., Jones, E. W., Obadia, B., Korasidis, N., … Ludington,
W. B. (2018). Microbiome interactions shape host fitness. Proceedings of the National
Academy of Sciences, 115(51), E11951–E11960. https://doi.org/10.1073/pnas.1809349115
The Gut Microbiome and Brain Health - Memory and Brain Wellness Center. (2018).
Retrieved October 11, 2020 http://depts.washington.edu/mbwc/news/article/the-gut-
The Human Microbiome Project: Extending the definition of what constitutes a human.
(2012).Retrieved October 7, 2020 https://www.genome.gov/27549400/the-human-
Your Microbes and You. (2017, June 26). Your Microbes and You. Retrieved October 7, 2020 https://newsinhealth.nih.gov/2012/11/yourmicrobesyou#:~:text=Humans%20need%20ba
cteria%20and%20their,and%20store%20energy%20from%20food.