What is Microbiome?
A microbiome is the collection of microorganisms that live on or inside a particular environment. In this case, we are talking about the microbiome in our human body. Microbes exist in your gut, oral cavity, and skin. In this essay, I would like to focus on the intestine and colon as they are among the densest microbial communities in your human body.
The gut microbiome has a profound impact on your mental health due to the gut-brain axis(GBA), a network of nerves and biochemical signals that connect the brain and the gastrointestinal tract.The GBA is a bidirectional communication system, meaning the bacteria in your gut can influence brain function, mood and mental health.
For example, a set of data collected from meta-analysis stated that from 10 clinical trials, 1349 patients suffering from depression had a significant improvement in mood after taking probiotics for 8 weeks.
Faecal transplant can also be used in treating anxiety and depression, using a small sample of faeces in a healthy colon for patients clinically suffering from depression and anxiety. This is because 90% of the body’s serotonin is produced in your gut and certain bacteria such as Bifidobacterium and Lactobacillus. Therefore, your gut microbiome can have a significant impact on your mental well-being if disrupted. In ‘Hack your health, the secret to your guts’ Doctor Giulia from Germany suggested that Microbiome is like a forest, only a few healthy plants wouldn’t make a forest, and you will need everything to work together to function.
Neurological Disorders
Gut microbiome perturbations may contribute to neurological diseases, including multiple sclerosis, Parkinson's disease, Alzheimer's disease, Huntington's disease, and amyotrophic lateral sclerosis (The disease Stephen Hawking had).
Parkinson’s disease is a progressive neurodegenerative disorder, in the CNS, enteric nervous system, peripheral autonomic nervous system due to the presence of Lewy body and several other factors.
Lewy Body-composed of mainly a protein called alpha synuclein, it can cause damage to the neurons in the areas of your brain that affect mental capabilities, movement, sleep and behaviour. E.g. the four lobes, cerebellum, hippocampus.
It is also a neurodegenerative disease causing the brain to eventually to shrink causing a decline in cognitivity. There are various causes of Alzheimer’s, your diet, genetically predisposed factors and your gender.
Probiotics treatments, including giving patients bacterias like bifidobacterium and lactobacillus. However there is a possibility of bias in the research as memory and cognitive ability is relatively subjective and there isn't a great way to measure it.
Also, fecal transplant has been proven to be useful by studies done in 2020,2021.
A 82 year old patient was subjected to 300ml of healthy faeces donated by his wife, showing a vast improvement in cognitive ability even after 6 months.
Gut Microbiome and Chronic Diseases
The gut microbiome, composed of trillions of microorganisms (bacteria, viruses, fungi, and other microbes) living in the gastrointestinal tract, plays a crucial role in maintaining health by assisting in digestion, immune regulation, and even influencing the brain. Disruptions in the balance of this microbial community, known as dysbiosis, have been linked to the development and progression of several chronic diseases.
Metabolic Disorders
Studies show that individuals with obesity tend to have a less diverse gut microbiome compared to those with a healthy weight and the composition of microbes in our gut has a huge effect on energy intake from food and promoting fat storage as well. For example the University Of Copenhagen extracted bacteria from 80 faeces of different people, results show that around 40% of the individuals extract more energy from food. (They do that by testing the residual energy in the faeces) Those people also weigh 10% more in comparison, roughly 9kg. The bacteria responsible for this is the Bacteroid Bacteria.
As for diabetes, multiple studies have reported gut microbiome dysbiosis as a factor of insulin resistance in about 90% of T2D worldwide. This is caused by the reshaping of the intestinal barrier, causing toxins like lipopolysaccharides which will increase insulin resistance by causing low-level inflammation (it activates proteins that suppress insulin signalling pathways), one of the key factors of T2D, lipopolysaccharides will be absorbed due to the increased permeability of intestine. Recent studies also showed that the F/B ratio or Firmicutes/Bacteroidetes, the two most abundant bacteria in the human body, can be a biomarker of T2D.
Conclusion
In conclusion, the microbiome, particularly in the gut, plays a vital role in maintaining human health and influencing diseases. The gut-brain axis demonstrates how gut bacteria impact mental health, with probiotics and faecal transplants offering potential treatments for conditions like depression and anxiety. Additionally, disruptions in the gut microbiome are linked to neurological disorders such as Parkinson's and Alzheimer's, as well as chronic diseases like obesity and diabetes. Understanding and maintaining a balanced microbiome through diet, probiotics, and other interventions could be key to preventing and managing various health conditions, highlighting the importance of ongoing research in this field.
Citations
Kho, Z., & Lal, S. (2018). The Human Gut Microbiome – A Potential Controller of Wellness and Disease. Frontiers in Microbiology, 9. https://doi.org/10.3389/fmicb.2018.01835.
Some guts are better than others at harvesting energy-University Of Copenhagen, faculty of science
Sharma, S., & Tripathi, P. (2019). Gut microbiome and type 2 diabetes: where we are and where to go?. The Journal of nutritional biochemistry, 63, 101-108 . https://doi.org/10.1016/j.jnutbio.2018.10.003.
K.Y. Hur, M.S. Lee
New mechanisms of metformin action: focusing on mitochondria and the gut
J Diabetes Investig, 6 (2015), pp. 600-609
Vendrik, K., Ooijevaar, R., Jong, P., Laman, J., Oosten, B., Hilten, J., Ducarmon, Q., Keller, J., Kuijper, E., & Contarino, M. (2020). Fecal Microbiota Transplantation in Neurological Disorders. Frontiers in Cellular and Infection Microbiology, 10. https://doi.org/10.3389/fcimb.2020.00098.
Bonnechère, B., Amin, N., & Duijn, C. (2022). What Are the Key Gut Microbiota Involved in Neurological Diseases? A Systematic Review. International Journal of Molecular Sciences, 23. https://doi.org/10.3390/ijms232213665.
