Recent years have seen a growing awareness of mental health issues, and, thankfully, more open conversations about addressing psychological challenges. However, many people remain unaware of new, exciting research on the connection between gut health and mental health. The connection between your digestive system and your brain can have a profound influence on your mental health, thanks to the complex communication network that exists between the two.
The Gut-Brain Axis
It may initially seem like a stretch to say your gut health affects your mood. So, let’s take a step back to look at the key terms. Your body’s organs do not exist in isolation, but rather are connected through complex networks that enable communication. Neurons are central to this process. They facilitate the communication between your brain and the rest of your body, everything from muscle reflexes, digestion to thoughts and emotions.
Neurotransmitters are the body’s chemical messengers, responsible for transmitting messages from neuron to neuron. When it comes to our mood regulation, an imbalance of certain neurotransmitters can result in mood disorders. Serotonin is one of these powerful neurotransmitters that regulates your mood, and a shortfall of serotonin can lead to depression.
The nervous system and vagus nerve
The Autonomic Nervous System (ANS) has three branches: the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system. The parasympathetic nervous system works to maintain homeostasis in the body and slow things down, while the sympathetic nervous system kicks in when there’s a threat or crisis and speeds up bodily functions. A good way to remember the difference is that the sympathetic nervous system works for “flight or fight” responses, and the parasympathetic is “rest and digest” responses.
One of the largest connections within the nervous system is the vagus nerve (also called the pneumogastric nerve), which sends two-way messages between your brain and your digestive system. The vagus nerve is part of the enteric nervous system, which independently controls functions of the gastrointestinal tract without input from the Central Nervous System (CNS) – the connection between the brain and spinal cord which controls most functions of the body and mind.
Disturbances in the balance between nervous systems can lead to physical problems that are triggered by a psychological component – like stress triggering IBS symptoms. The vagus nerve helps with the parasympathetic nervous system to keep your body in “rest and digest” and helps to slow down the flight or fight responses that can wreak havoc on mental and physical health. Studies show that poor vagal tone can lead to difficulties regulating emotional responses.
The microbiome connection
Your gut is also a microbiome for trillions of microbes, which are bacteria, fungi and even viruses. These microbes play a large role in your health, including your mental health. They’re responsible for most of the production of the “happy” neurotransmitter, serotonin. The microbiome also helps produce gamma-aminobutyric acid (GABA), which is a neurotransmitter that regulates anxiety. Some studies have found that gut microbiomes can also activate the vagus nerve (more on activating the vagus nerve below!)
Gut Health And Your Mood
As you can see from all the “messengers” described above, your brain and your gut have constant bi-directional communication. That explains the queasy feelings that accompany nervousness (or even love!). But it’s important to remember that communication flows both ways. Disturbances in your gut can affect your brain, and as a result, there is a profound correlation between your gut bacteria and your mental health. Imbalances in the microbiome can reduce serotonin production.
3 Ways To Optimize Your Gut Health and Improve Mental Health
Eat a gut friendly diet
Optimum gut health depends on many different factors, but one thing we can control is the food we eat. Studies suggest that diversity of microbes offers the best protection, and your diet can play a role in creating this diversity. Unfortunately, the typical North American diet of processed foods doesn’t typically have a lot of diversity. The following foods can help increase bacteria.
- Omega-3 fats aid in gut health and cognitive function. They are found in fatty fish, like salmon, nuts and seeds, like walnuts and chia seeds, and some plant oils, like flax seeds.
- Foods high in polyphenols which include chocolate, coffee, and green tea. Polyphenols help by enhancing the growth of beneficial bacteria and inhibiting the growth of pathogens
- Fermented foods contain high amounts of the beneficial bacteria lactobacilli which add to our gut microbiome. Good sources of fermented foods include kefir, yogurt (choose unsweetened when possible, and add fresh fruit), kimchi, miso and tempeh.
- Whole grains can also increase bacteria. Although some studies have found this benefit only applies to gluten-free grains.
- Focus on Dietary fiber is metabolized by bacteria in your gut, which helps stimulate good bacteria growth.
- Probiotic supplements can increase the number of good bacteria in your gut. The quality of supplements sold varies quite widely, so work with a healthcare practitioner to find the right ones for you.
Slow down, stay hydrated and move your body
A few lifestyle changes to incorporate to help optimize your gut health and improve mental health include:
- Mindful eating. Slow down when you eat to take a break from your day which will help ease stress and anxiety. Help your body digest these healthy foods by chewing slowly and savoring your meals in a relaxing environment. By chewing slower you are breaking foods down adequately before they reach the stomach.
- Don’t forget to drink plenty of water. Staying hydrated is important for all bodily functions, helps protect the microbiome, and aids in digestion. Aim for 2 – 3L a day of fresh, filtered water and consume fruit and vegetables to stay adequately hydrated throughout the day.
- Get moving! Exercise will aid digestion and stimulate peristalsis, the action of food moving through the digestive tract. This stimulation will help prevent constipation and improve elimination to keep you regular. Studies show that engaging in regular exercise may help improve mental health by reducing anxiety, depression, and negative mood and by improving self-esteem and cognitive function.
Stimulate the vagus nerve
New research is being done regarding natural vagus nerve stimulation (without the electronic impulses done in a clinical setting). This helps to “tone” the vagus nerve to improve its function, and, therefore, your ability to slow the fight or flight response. Studies have shown that people with a strong vagus respond better to stress. To activate your vagus nerve:
- Practice deep breathing. Slow, deep breathing (about six breaths per minute) can condition the vagus nerve and the rest of the parasympathetic nervous system.
- Sing, hum, or gargle to strengthen your vocal chords, which are connected to the vagus nerve. Laughing has a similar effect.
- Immerse your face in cold water. It might seem counterintuitive, but this can slow your sympathetic nervous system’s flight-or-fight response and tone your vagus nerve.
Protecting your mental health is best approached with a multifaceted approach that includes optimizing your gut health. While it is also important to maintain your optimal hormone levels and other processes in the body for your mental health, keeping in mind the importance of what you feed your body also key in achieving your best.
Breit Sigrid, Kupferberg Aleksandra, Rogler Gerhard, Hasler Gregor, Vagus Nerve as Modulator of the Brain–Gut Axis in Psychiatric and Inflammatory Disorders , Frontiers in Psychiatry, volume 9, DOI=10.3389/fpsyt.2018.00044
Mayer EA. Gut feelings: the emerging biology of gut-brain communication. Nat Rev Neurosci. 2011;12(8):453-466. Published 2011 Jul 13. doi:10.1038/nrn3071
Forsythe P, Bienenstock J, Kunze WA. Vagal pathways for microbiome-brain-gut axis communication. Adv Exp Med Biol. 2014;817:115-33. doi: 10.1007/978-1-4939-0897-4_5. PMID: 24997031.
Sun LJ, Li JN, Nie YZ. Gut hormones in microbiota-gut-brain cross-talk. Chin Med J (Engl). 2020;133(7):826-833. doi:10.1097/CM9.0000000000000706
Limbana T, Khan F, Eskander N. Gut Microbiome and Depression: How Microbes Affect the Way We Think. Cureus. 2020;12(8):e9966. Published 2020 Aug 23. doi:10.7759/cureus.9966
Menni C, Zierer J, Pallister T, et al. Omega-3 fatty acids correlate with gut microbiome diversity and production of N-carbamylglutamate in middle aged and elderly women. Sci Rep. 2017;7(1):11079. Published 2017 Sep 11. doi:10.1038/s41598-017-10382-2
Hansen LBS, Roager HM, Søndertoft NB, et al. A low-gluten diet induces changes in the intestinal microbiome of healthy Danish adults. Nat Commun. 2018;9(1):4630. Published 2018 Nov 13. doi:10.1038/s41467-018-07019-x
McLaughlin KA, Rith-Najarian L, Dirks MA, Sheridan MA. Low vagal tone magnifies the association between psychosocial stress exposure and internalizing psychopathology in adolescents. J Clin Child Adolesc Psychol. 2015;44(2):314-328. doi:10.1080/15374416.2013.843464