Have you ever experienced bloating at home, only to go on a (much deserved) vacation and realize your bloat is nowhere to be found? Or maybe you’ve noticed that in times of stress, no matter what you eat, your belly hurts like never before? That’s because our brain and gut are connected in a bidirectional way; this means, whatever we’re thinking or feeling emotionally can have direct and drastic effects on our digestive system! This problem is all too relatable, and of course, when we’re feeling stressed, the last thing we want to worry about is our bloated belly. Read on to find out exactly whythis happens, what this means for our health, and howwe can prevent, and tend to, our bodies when a flare-up happens.
What is the Gut-Brain Axis, exactly?
The Gut-Brain Axis, or GBA, is a bidirectional link between the central nervous system, or CNS, and the enteric nervous system, ENS. Our CNS, being central to our body, is made up of our brain and spinal cord. It helps us integrate the information we receive into proper responses by our body. By coordinating and influencing what we do, our CNS is therefore responsible for all voluntary movements, like speech and walking, and involuntary movements, like blinking and our heart beating. Essentially, our CNS dictates everything we do and helps us to stay alive by controlling our body’s necessary functions.
The enteric nervous system (ENS) is a part of our autonomic nervous system, and is found in the walls of our digestive tract. It includes various neural circuits that control motor functions, blood flow, immune function, hormone release and balance, and especially our digestive system. The ENS is able to control digestive behavior independently of the CNS, and researchers found that ENS dysfunction directly impacts digestive disorders in a negative way. The ENS has large, two-way connections with the CNS; the two work together to control our digestive system within local and whole body physiological demands.
The science might seem daunting, but the gist of it is that our digestive system is controlled by a web of interconnected neurons and complex systems that help us to release hunger hormones, physically eat, digest through our body, and excrete waste. The GBA involves direct and indirect pathways between cognitive and emotional centers in the brain along with digestive functioning. From hormones to our immune system to our fight or flight and rest and digest systems, it’s easy to see that our digestion is impacted by a whole bunch of different systems within our body. Our GBA, as a whole, is influenced by our gut microbiota, microscopic bacteria that live in the walls of our gut, making up the gut microbiome.
The Gut Microbiome
The word “microbiome” refers to all microorganisms in or on our bodies as well as the genetic material they’re made up of. There are approximately one hundred trillion of these microorganisms in the gut; that’s 10 times as many cells as there are in the rest of the body. While the gut microbiome is tucked away in our digestive system, it impacts our entire body, and therefore, our health. The bacteria help us to digest fiber, control our immune system, and help us to control brain health.
Fiber: Certain types of bacteria digest the fiber from the foods we eat, converting it into short-chain fatty acids. These fatty acids maintain our intestinal barriers, and are anti-inflammatory, making them important for our gut health.
Immune System:Much like our gut and our brain, our gut and our immune system communicate with each other. Our microbiome can influence the inflammatory response to our immune system, therefore controlling how we respond to infection.
Brain Health: New research has found that our gut microbiota communicates with the central nervous system through neural, hormonal, and immune pathways, therefore influencing both brain function and behavior. Scientists have found that individuals with various mental health disorders have different bacteria in their gut as compared to those who don’t. Cool, right?!
All in all, these tiny microorganisms dictate a lot of our body’s processes, impacting how we feel! Later on, we’ll let you in on some tips and tricks to keep you, and your microbiome, happy.
The Gut and Gut Health
Obviously, by being in the gut, these bacteria significantly impact our gut health and play a role in the development of intestinal disorders like IBS and IBD. The bloating, cramping, and abdominal pain that we experience from time to time (or every day) may be due to an unbalanced gut microbiome, or gut dysbiosis. When the balance of ‘good’ and ‘bad’ bacteria is off kilter, meaning there’s more bad than good, these organisms take charge of the gut and produce a lot of gas and other chemicals. So, your gut bacteria are to blame for all of your bloat symptoms!
The Vagus Nerve
The vagus nerve is one of the biggest nerves connecting the gut and brain, sending signals in both directions. Like we’ve learned, much of what is produced in the gut has large impacts on our mood and behavior. Neurotransmitters are hormones that carry chemical messages from one cell to the next, endlessly working to control our body’s and keep us in a stable state. Some popular ones include serotonin–the “feel good” chemical, dopamine–the reward center neurotransmitter–, and norepinephrine–aka adrenaline, giving us that natural high sensation. While these neurotransmitters are primarily produced by the brain, many of them are also produced by the digestive tract’s cells. Serotonin, especially, is produced in large amounts in the gut; this may be why we often don’t feel so happy when experiencing tummy troubles.
Probiotics
Many of us take probiotics, but do we even know why? Probiotics are live bacteria that have multiple benefits of feeding our ‘good’ bacteria, lowering the ratio of good:bad. Probiotics have been shown to reduce levels of anxiety, stress, and depression. When our body’s gut microbiome is balanced, many of the not-so-great symptoms (think bloating, irritability, stress) can be decreased or even go away completely. One study found that treatment with a specific probiotic reduced the stress-induced release of cortisol, reducing feelings of anxiety. See, it’s all connected!
The Gut-Brain Connection and Diet
Now that we have a good idea of the science behind this connection, it’s time to talk about food. There are various food groups that are great for our gut, and some that should only be eaten in moderation.
Omega-3s: Found in fish, vegetable oils, nuts, seeds, and leafy greens, Omega-3s have been found to increase good bacteria in the gut, promoting overall health.
Fermented Foods: Foods like kimchi, Greek yogurt, and sauerkraut increase the diversity of our gut microbes, which is directly correlated with improved health.
High Fiber Foods: Whole grains, fruits, veggies, and nuts all contain fibers that our good gut bacteria love! This helps create a better ratio of good:bad bacteria.
Polyphenols: Some of our favorites, including coffee, olive oil, and cocoa contain polyphenols. These chemicals directly increase healthy bacteria.
Alcohol: The Dietary Guidelines for Americans recommend two drinks or less a day for men and one drink or less a day for women. Alcohol harms our gut, by creating gut dysbiosis.
Processed Foods:The additives in these foods, along with their low fiber content, affect our gut microbiome negatively. Processed foods can also impact the amount of serotonin made in the gut, leading to decreased mood and anxiety.
Overall, our body is an intricate web system. Everything we do and eat has a domino effect on how we feel. Sticking to a whole foods diet, avoiding highly processed foods, and taking probiotics are the best ways to feed our gut.
References:
Furness, John B. “Enteric Nervous System.”Scholarpedia, http://www.scholarpedia.org/article/Enteric_nervous_system.
Schmidt, Kristin, et al. “Prebiotic Intake Reduces the Waking Cortisol Response and Alters Emotional Bias in Healthy Volunteers.”Psychopharmacology, Springer Berlin Heidelberg, May 2015, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4410136/.
TG;, Cryan JF;Dinan. “Mind-Altering Microorganisms: The Impact of the Gut Microbiota on Brain and Behaviour.”Nature Reviews. Neuroscience, U.S. National Library of Medicine, https://pubmed.ncbi.nlm.nih.gov/22968153/.
WS;, Rooks MG;Garrett. “Gut Microbiota, Metabolites and Host Immunity.”Nature Reviews. Immunology, U.S. National Library of Medicine, https://pubmed.ncbi.nlm.nih.gov/27231050/.
