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The Gut-Brain Connection
The Gut-Brain Connection: How Gut Health Impacts Mental Health
In recent years, scientific research has illuminated a profound connection between the gut and the brain, revolutionising our understanding of mental health. Known as the “gut-brain axis,” this bidirectional communication network links the central nervous system (CNS) with the digestive system. Central to this relationship is the gut microbiome. Emerging evidence suggests that gut health significantly influences mental health conditions such as depression, anxiety, and stress. In this blog, we will explore the science behind the gut-brain connection and provide actionable strategies to support gut health for improved mental well-being.
Understanding the Gut-Brain Axis
The gut-brain axis involves a constant exchange of signals between the gut and the brain (source) via:
- The Vagus Nerve: The vagus nerve acts as a communication superhighway, transmitting signals between the gut and the brain.
- The Enteric Nervous System (ENS): Often referred to as the “second brain,” the ENS in the gut operates semi-independently, influencing digestive processes and interacting with the central nervous system.
- Metabolite Production: The gut microbiome produces various metabolites such as the short chain fatty acid butyrate (which we discussed in our previous blog here), and key neurotransmitters, including serotonin (about 90% of the body’s total serotonin), which play critical roles in regulating mood.
- The Immune System: Approximately 70% of the immune system resides in the gut. Inflammatory responses originating from the gut can affect brain function and mood.
The Role of the Gut Microbiome
The gut microbiome comprises bacteria, viruses, fungi, and other microorganisms. It plays a vital role in digestion, immunity, and even mood regulation. Dysbiosis—an imbalance in the microbiome—has been linked to mental health disorders through several mechanisms (source):
- Inflammation: Imbalanced gut bacteria can trigger chronic inflammation, which is associated with depression and anxiety.
- Neurotransmitter Disruption: As mentioned certain gut bacteria help produce neurotransmitters like GABA, serotonin, and dopamine. Dysbiosis can reduce their availability, potentially leading to mood disorders.
- Stress Response: A disrupted gut microbiome can amplify the body’s stress response by affecting cortisol levels.
Evidence For The Gut-Brain Connection
1. Depression
A 2019 study published in Nature Microbiology found that individuals with depression often have lower levels of certain gut bacteria, such as Coprococcus and Dialister. These bacteria are involved in anti-inflammatory pathways and the production of short-chain fatty acids (SCFAs) like butyrate, which are crucial for brain health.
Recommended Product: Bio.Me Barrier. This multi-strain probiotic has been shown to improve depression in clinical studies (source).
2. Anxiety
Research in General Psychiatry (2019) highlighted that probiotics, which modulate the gut microbiome, significantly reduced anxiety symptoms in several clinical trials. This underscores the microbiome’s influence on stress and anxiety pathways.
Recommended Product: Ideal Bowel Support. This specific strain of lactobacillus has been shown to lower anxiety and cortisol (source).
3. Stress
A 2021 meta-analysis in Frontiers in Psychiatry demonstrated that gut-directed therapies, including dietary changes and probiotics, effectively reduced stress levels. The findings suggest that gut health interventions can modulate the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the stress response.
Recommended product: ZenBiome. This strain of lactobacillus has been shown to improve perceived stress, cortisol and anxiety. (source)
5 Ways to Support The Gut-Brain Connection
1. Eat a ‘Psychobiotic Diet’
In one study (source) participants were instructed to eat and educated on a ‘psychobiotic diet’.
The foods in focus of the psychobiotic diet included those known to influence the microbiome, namely, whole grains, prebiotic fruits and vegetables, fermented foods, and legumes while discouraging consumption of “unhealthy” foods such as sweets, fast food or sugary drinks.
Participants were educated on the components of the study diet, which included consumption of fruits and vegetables high in prebiotic fibres (6–8 servings per day, e.g., onions, leeks, cabbage, apples, bananas, oats), grains (5–8 servings per day) and legumes (3–4 servings per week) as well as fermented foods (2–3 servings per day, e.g., sauerkraut, kefir or Kombucha). For fermented foods, one serving equaled 200 ml or one cup.
The take away was that a short term psychobiotic dietary intervention improved perceived stress in a healthy population. This is not an isolated paper, there are countless examples of how dietary changes can improve our mental health.
2. Incorporate Fermented Foods
According to a meta-analysis published in 2023 (source) fermented dairy foods intake may have potential beneficial effect on depression via the gut-brain axis. Fermented foods are foods such as yogurt, kefir, kimchi, sauerkraut, and miso.
Why not try culturing your own kefir using this product.
3. Take Evidence Based Probiotics
Probiotics are live microorganisms that support a balanced microbiome. As mentioned above, clinical studies suggest that specific strains of Lactobacillus and Bifidobacterium can reduce symptoms of stress, depression, anxiety, and improve gut health. It is important to appreciate that specific strains of probiotic have to be selected – not all probiotics will improve mental health, like not all probiotics will improve your gut health.
Probiotics have to be specifically selected based on their strain and the disease being treated (we have an upcoming blog breaking this down). (source).
For example in a randomised, triple-blind, placebo-controlled trial of probiotics for depressive symptoms demonstrated that a probiotic improved cognitive reactivity, associated with susceptibility to depression.
4. Manage Stress
Chronic stress can alter the gut microbiome, exacerbating dysbiosis and cause IBS (source). Practices such as mindfulness, meditation, yoga, and deep breathing exercises can help regulate the gut-brain axis by reducing stress.
Diaphragmatic breathing has been shown to benefit those suffering with depression and IBS, and is a simple practice. Simply lie down in a comfortable position. Place one hand on your belly and breath in through your nose for a count of five seconds, and out through the nose for a count of five seconds. Feel the rise and fall of your belly with each inhale and exhale. There should be limited movement in the chest. Practice for at least 5 minutes and aim to practice every day. Sometimes the simple things are the most powerful!
5. Limit Processed Foods and Sugar
Highly processed foods, sugar and various preservatives/additives can promote the growth of harmful gut bacteria and increase inflammation (source). Opt for whole, nutrient-dense foods to maintain a healthy microbiome.
Conclusion
The gut-brain connection is a dynamic interplay that shapes both our physical and mental health. By understanding the crucial role of the gut microbiome, we can take proactive steps to nurture gut health and, in turn, improve our mental well-being. Incorporating dietary changes, stress management techniques, and targeted supplements can pave the way for a healthier gut and a happier mind.
Learn more about your microbiome by completing our ultimate gut health test.
References
- Clarke, G., Stilling, R. M., Kennedy, P. J., Stanton, C., Cryan, J. F., & Dinan, T. G. (2014). Minireview: Gut microbiota: The neglected endocrine organ. Molecular Endocrinology, 28(8), 1221-1238.
- Valles-Colomer, M., Falony, G., Darzi, Y., et al. (2019). The neuroactive potential of the human gut microbiota in quality of life and depression. Nature Microbiology, 4, 623–632.
- Zhang, Y., Li, N., Li, S., et al. (2019). Probiotics reduce depressive symptoms in patients with major depressive disorder: A meta-analysis. Psychiatry Research, 282, 112568.
- Chao, M. T., Wade, C. M., & Booth, S. L. (2021). Gut-brain axis: Mechanisms, interactions, and implications for mental health. Frontiers in Psychiatry, 12, 723914.
- Foster, J. A., Rinaman, L., & Cryan, J. F. (2017). Stress & the gut-brain axis: Regulation by the microbiome. Neurobiology of Stress, 7, 124-136.
