Improving the Gut-Brain Connection through Nutrition
If you've ever had "butterflies" in the stomach, you have experienced the gut-brain connection. This relatively new discovery has profound implications especially for mental and physical medical conditions such as anxiety and chronic bowel disease. One of the impacts is the extent to which a healthy microbiome improves the connection between the gut and the brain. And improving the microbiome is simple: Eat foods that encourage healthy gut bacteria.
Gut-Brain Connection and Vagus Nerve
The gut-brain connection refers to the partnership between the digestive system and the brain which is also known as the gut-brain axis. Specifically, there is two-way communication between the brain and the gut. It's like two best friends telling each other their secrets, feelings, etc. However, they communicate through neurotransmitters and a network of neurons that are in the central nervous system (CNS), brain, and gut instead of words.
Twelve cranial nerves send messages from the body to various parts of the body. The longest cranial nerve is the vagus nerve. The gag reflex is a reaction caused by the vagus nerve. It runs from the colon to the brain stem and sends the brain information from the gut.
Human studies showed that vagal tone (strength of the vagal nerve) was reduced in people with irritable bowel syndrome (IBS) and Crohn's disease. And an animal study found that stress hindered signals from the vagus nerve. Another study showed that participants with post-traumatic stress disorder (PTSD), when faced with a challenge, had different vagal activity that affected their heart rate than those participants who didn't have PTSD.
"‘The system is way too complicated to have evolved only to make sure things move out of your colon.... A big part of our emotions are probably influenced by the nerves in our gut….' Emeran Mayer, professor of physiology, psychiatry and biobehavioral sciences at the David Geffen School of Medicine at the University of California, Los Angeles (U.C.L.A.)."[i]
A microbiome is a community of microbes, such as bacteria that live in the gut. There are over a trillion microorganisms in and on the body, and the community of microbes can vary from person to person. The gut microbiome impact on health is considered one of the most important medical discoveries in recent times. One finding is that the gut microbiome has its own circadian rhythm and a high-fat diet can alter it which in turn can affect an individual's circadian clock.
Food, Nutrition, and Gut-Brain Connection
Why is diet important to the gut-brain axis? Diet, especially fat and fiber can radically impact gut bacteria and can do it immediately. In turn, gut microbes influence the type of communication between the brain and the gut primarily through the vagus nerve.
The activation of the vagus nerve is crucial to the brain's mediating effects on behavior.[ii]
Also, gut microbes produce other chemicals from digesting dietary fiber, such as short-chain fatty acids (SCFA) that affect brain function. For example, SCFA has been shown to reduce appetite and modulate reward-based eating.
Also, it was once thought that the CNS was immune to inflammation. It is now known that the CNS is affected by inflammation and can produce inflammatory cells. Lipopolysaccharides (LPS) are inflammatory, and if too much of it passes from the gut into the bloodstream, it can cause inflammation and gut permeability. Excess inflammation has been linked to many conditions of the brain like Alzheimer's disease and depression. An increase in LPS is associated with gut flora imbalance and diet plays a significant role in helping to reduce inflammation.
Probiotics and Prebiotics to Improve Gut-Brain Connection
The first piece of good news is that the gut-brain connection can be improved by improving the health of the gut. The second piece of good news is that it can be accomplished fairly easily by changing or adjusting the diet.
While probiotics are in general beneficial for gut health, certain probiotics are especially helpful for the brain; they are called psychobiotics. The bacteria in this class of probiotic deliver neuroactive elements, such as serotonin and gamma-aminobutyric acid that act on the brain-gut axis. Bifidobacterium and Lactobacillus are two of the psychobiotics that have been identified that may lessen depression and alter brain activity in patients with IBS.
Here's a list of the top probiotic foods
Yogurt – However, all yogurt is not equal when it comes to bacteria. Only yogurt with live cultures is beneficial. Also, many yogurts are high in sugar which negates some of the healthy benefits.
Miso – Miso is made from fermented rice, beans, soy, or barley. Miso soup is easy and quick to make.
Pickles and pickled vegetables – These are an easy and quick way to add some probiotics to your diet. You can even make your own refrigerated pickled and pickled vegetables that do not require canning.
Sauerkraut – Sauerkraut is fermented cabbage. Buy unpasteurized sauerkraut, which is found in the refrigerated section of the grocery store, to get the highest probiotic effects.
Kimchi – This Korean side dish is a mixture of pickled vegetables that is found in the refrigerated section of stores. It's often spicy so read the label if spicy foods bother you.
Kombucha – While relatively new to the U.S., kombucha has been drunk for centuries in Asian countries and parts of Russia.
Tempeh – Tempeh is often a meat or tofu substitute. It a fermented soybean food that can be baked, sautéed, or crumbled on salads.
Probiotics supplements can also be purchased. Follow package directions for use.
Psychobiotics has been extended to include prebiotics. Prebiotics are foods that are fermented in the gut and promote the growth of beneficial gut microflora. These non-digestible fiber compounds don't digest and pass to the small intestines where gut bacteria ferment them.
Most prebiotics are eaten raw, such as:
- Not fully ripe bananas
- Dandelion greens
- Microalgae – These are ocean-based foods like chlorella, seaweed, and spirulina.
While research continues into the microbiome and gut-brain axis effect on the body's health and their connection to diseases and the prevention of them, one thing is clear: Nutrition plays a crucial role in keeping the gut-brain axis healthy.
Axe, Dr. 7 Reason to Get Prebiotics in Your Diet – Plus the Best Sources. Retrieved from https://draxe.com/prebiotics/.mic
Byrne, C.S., et al. Increased colonic propionate reduces anticipatory reward responses in the human striatum to high-energy food (May 11, 2016). Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/27169834.
Chambers, Edward S., et al. Effects of targeted delivery of propionate to the human colon on appetite regulation, body weight maintenance and adiposity in overweight adults (November 2015). Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4680171/.
Forsythe, P, et al. Vagal pathways for microbiome-brain-gut axis communication (2014). Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/24997031.
Hadhazy, Adam. Think Twice: How the Gut's "Second Brain" Influences Mood and Well-Being (February 12, 2010). Retrieved from https://www.scientificamerican.com/article/gut-second-brain/.
Pinto-Sanchez, M.I., et al. Probiotics Bifidobacterium longum NCC3001 Reduces Depression Scores and Alters Brain Activity: A Pilot Study in Patients With Irritable Bowel Syndrome (May 5, 2017). Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/28483500.
Pizzomo, Joseph, ND, Editor in Chief. Toxins From the Gut (December 13, 2014). Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4566437/.
Robertson, Ruairi, Ph.D. The Gut-Brain Connection: How It Works and The Role of Nutrition (June 27, 2018). Retrieved from https://www.healthline.com/nutrition/gut-brain-connection.
Sahar, T, et al. Vagal modulation of responses to mental challenge in posttraumatic stress disorder (April 1, 2001). Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/11297721.
Sarkar, Amar. Psychobiotics and the Manipulation of Bacteria–Gut–Brain Signals (November 2016). Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102282/.
Seladi-Schulman, Ph.D. Vagus Nerve Overview (July 31, 2018). Retrieved from https://www.healthline.com/human-body-maps/vagus-nerve#stimulation.
[i] Hadhazy, Adam, Think Twice: How the Gut's "Second Brain" Influences Mood and Well-Being, February 12, 2010. Web.
[ii] Forsythe, P, et al., Vagal pathways for microbiome-brain-gut axis communication (2014). Web.
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