Our gut is called the second brain as it has about 100 million neurons and this number is more compared to both the spinal cord and peripheral nervous system. It has got sheaths of neurons that are embedded in the walls of the alimentary canal which extends from the mouth to the anus and is about 9 meters long. The bidirectional communication between the microbiota in the gut and central nervous system is called the gut-brain axis. Healthy gut function has been linked to normal central nervous system function. The hormones, neurotransmitters, and immunological factors produced by the gut play a key role in communicating with the brain directly or via autonomic neurons.
According to Counseling Psychologist, Anwesha Gupta, “Basically, cortisol is our stress hormone. So, when we experience a lot of stress, cortisol is released in excess. This excessive release of cortisol directly affects our gut, which in turn reduces the secretion of enzymes that aid in digestion. Additionally, stress often leads to changes in our eating patterns and habits. This connection between stress, gut health, and eating habits highlights the strong link between the mind and the gut.”
In Literature
Both Humanities and Biomedicine should consider the concept of The thinking gut for a better understanding. Language has always linked the gut with ‘feeling states.‘ Gut instinct’ and ‘trusting the gut’ are notions that are often used in the literature of the English language. “Butterflies in the stomach” is another idiom that is often used to express feelings of anxiety and nervousness in both positive and negative situations.
The gut engages all the senses from the sound and feel of the process of digestion to the responses to the smell, taste or sight of certain foods or experiences and, as such, requires a sensory, bodily approach to connect with these aspects.
In biomedicine
Sudo and Colleagues conducted a landmark study that discovered the concept of the gut-brain axis. The study was conducted on germ-free mice via impaired stress response even later study on the same sample supported the existence of the gut-brain axis and the idea that the gut-brain axis is not just about these two systems and it extends into the neural, endocrine, and immune pathways. A recent area of research interest is the effect of the types of microbiomes on different CNS disorders.
Related: Understanding Stress: Types, Causes, and Coping Strategies
Microbiome development
The microbiome is initially developed via vertical transmission through the placenta, amniotic fluid. Animal studies concluded that fetuses who are exposed to prenatal stress in the form of maternal stress develop a gut microbiota with decreased Bifidobacterium. Studies concluded that the mode of delivery is important when it comes to the initial microbiome and gut microbiota. Infants delivered vaginally had more amounts of bacteria in the gut when compared to infants delivered by Cesarean section. The first week of life is highly critical and GI development is essential for newborn health and immunity. Lack of enough microbiota development during this period has been correlated with numerous stress states including late-onset sepsis, cardiovascular diseases, and atopic disease.
Read more; The Relation Between Your Stress and Gut
Early nutrition and breastfeeding have an important role to play in microbiome development. Studies suggest the non-digestible sugars found in breast milk provide a prime nutritional source that helps bacterial fermentation. Halting of breastfeeding is the primary diet change that develops an adult-like microbiome. Children who were weaned from breast milk up to age four children weaned at an earlier age showed a similarity of microbiota development, which indicates that the length of time to transition from breast milk to hard or solid foods was not as significant as the transition itself.
The relationship between the gut microbiota and diet extends throughout the life. Diet changes can have an impact on the gut bacterial composition in as little as 24 hours. However, If the diet is temporary then the body can restore bacterial composition. Regardless of the species inhabiting the gut, as long as their symbiotic role is the same, the host will be capable of functioning normally. Symbiotic bacteria assist with immune tolerance, intestinal homeostasis, amino acid, and vitamin synthesis of the host, leading to a healthy metabolism.
Gut and Health
When our body is under pressure, anxious or nervous it releases some chemicals and hormones into the digestive system. This will affect the microorganisms living along the gut region that is significant in the phenomenon of digestion and there will also be a decrease in antibody production. The resulting chemical imbalance can cause several gastrointestinal conditions such as indigestion, and diarrhoea, stomach, Irritable Bowel Syndrome, Constipation, Loss of appetite, Nausea.
The gut microbiota produces neurotransmitters that regulate brain activity and affect mood, stress, and anxiety. For example, Lactobacilli and Bifidobacteria produce GABA, and Escherichia coli produce serotonin. Emerging evidence suggests that imbalances in the gut microbiota can disrupt communication between the brain and gut, potentially leading to mental health disorders such as Anxiety, Depression, Neurodevelopmental conditions, Alzheimer‘s disease, Autism, Bipolar disorder, and Dementia.
According to Assistant Professor, Dr. Harguneet Kaur “gut and brain are interlinked. Our gastrointestinal system comprises of stomach, intestine, and colon. The brain is an important part of our central nervous system. Research shows that there exists another brain, which is seated in our gut, and is called as the ‘Enteric Nervous System’. There exists a bi-directional communication between these two. Now, that implies that whatever we eat and how well we digest it has an impact on our brain and therefore on our mood, emotions, etc. Let’s say a person has a disorder of the gastrointestinal tract, irritable bowel syndrome (IBS) common symptoms of which are pain, diarrhoea, gas, bloating etc., may lead to ‘state anxiety’ in that person. It could also lead to depression in the person for some time, lesser motivation to do simple routine activities, and may affect his or her work performance.”
She Further Explains, “Now, that is why, you know, more and more, gastroenterologists today are, stressing that along with medication one should go for counselling, especially gut-focused relaxation training. IBS could be because of some bacterial growth, infections, side effects of certain medications, cancerous growth, etc., in the body. In scenarios where no medical reason is identified, stress is attributed as a possible cause. Now, stress could be because there in reality exists a significant stressor in the life of a person, or it could be that it is all in his mind. The mind may exaggerate something trivial if the person uses unproductive or dysfunctional coping skills or is disoriented from reality.”
Speaking Further, “Recent research is suggesting if we take care of our gut health well, our mind is also well taken care of. For example, if we take probiotics naturally in the form of yoghurt, fruits like custard apples or even bananas for that matter or in the form of medicine it may elevate our mood. However, more research is needed in this area.”
Better Diet Better health
People in rural areas have higher amounts of microbiomes in their gut when compared to people in urban areas. Tribals have a higher diversity of bacteria in their gut as they have a rich variety of plant-based food in their diet. You should feed your bacteria with good food and not junk. Eat more vegetables, legumes, fermented food and fruits. Have food items and supplements rich in antioxidants, vitamins, calcium, protein and fibre for a better diet and better health.
Take Away
What you are eating will determine your health. This is not just about physical health but about mental well-being too. Lifestyle changes, technological advancement and evolution have already led to loss of the diverse microbiomes. We will not be able to bring them back but we can find ways to increase the number of these lifeforms by following better diets.
References +
- Lucas, G. (2018). Gut thinking: the gut microbiome and mental health beyond the head. Microbial Ecology in Health and Disease, 29(2), 1548250. https://doi.org/10.1080/16512235.2018.1548250
- Clapp, M., Aurora, N., Herrera, L., Bhatia, M., Wilen, E., & Wakefield, S. (2017). Gut microbiota’s effect on mental health: The Gut-Brain axis. Clinics and Practice, 7(4), 987. https://doi.org/10.4081/cp.2017.987
- Hadhazy, A. (2024, February 20). Think twice: How the gut’s “Second brain” influences Mood and Well-Being. Scientific American. https://www.scientificamerican.com/article/gut-second-brain/
- WebMD Editorial Contributors. (2023, April 9). How to improve your gut health and mental health. WebMD. https://www.webmd.com/digestive-disorders/how-to-improve-your-gut-health-and-mental-health
- c=AU; o=The State of Queensland; ou=Queensland Health; ou=; ou=; (2022, August 26). The links between your gut microbiome and mental health: is your bug half affecting your mental wellbeing? Queensland Health. https://www.health.qld.gov.au/newsroom/features/the-links-between-your-gut-microbiome-and-mental-health-is-your-bug-half-affecting-your-mental-wellbeing
