Anxiety and the gut

Anxiety and the gut

One of the most common topics discussed within functional medicine is supporting and creating a healthy gut microbiome. But what exactly is this gut microbiome and why is it so important? The gut is a multi-organ system that covers the stomach, intestines, and colon. The microbiome consists of trillions of commensal microbes that live in your gut. These microbes include bacteria, fungi, protozoa, and even some viruses. Specifically, some of the most common species to be found in the gut include Bacteroidetes, Firmicutes, Actinobacteria, and Proteobacteria phyla.¹ The importance of the gut microbiome lies in that it significantly determines many aspects of your health. For example, a healthy gut microbiome supports functions of sleep quality, immunity, mental health, cancer prevention, and many other aspects that many people desire.²

The gut and mood

But how is the gut connected to mood? Many researchers argue that one can see how connected the gut is to mental health by observing some of the physical side effects of mental illness. A few examples of this connection would be individuals with major depressive disorder having changes in appetite and increased weight, people with anxiety struggling with nausea and diarrhea, and people with irritable bowel syndrome having changes in overall mood, increased anxiety, and increased stress levels.³ Ultimately, it has been found that the gut microbiome plays an essential role in creating hormones essential for mood. The gut communicates with the central nervous system through a system called the gut-brain-axis.⁴

The gut-brain axis

This gut-brain-axis is connected with many different organs like the hypothalamus, pituitary glands, and adrenal glands. All these organs modulate stress and overall mood by releasing different hormones and neurotransmitters in response to signals from the gut-brain-axis. One study found that approximately 95% of natural serotonin is created within the gut microbiome. Other neurohormones created and monitored by the gut microbiome include cortisol, norepinephrine, GABA, melatonin, histamine, and acetylcholine.⁵ Furthermore, the gut microbiome also creates vitamin K-2 and the following B-vitamins: niacin (B-3), biotin (B-7), folate (B-9), and pyroxidine (B-6). Specifically in people with depression, folate and pyroxidine are commonly lacking which can be causing some of the symptoms.⁶ Clearly, maintaining a happy and healthy gut microbiome is essential for fighting anxiety and depression through the creation of essential hormones and vitamins.

Diet and the gut

One of the factors that deeply influences the health of the gut microbiome is nutritional diet. Studies have even shown that nutrition and the gut microbiome can influence things like stress management, anxiety, and depression. One study discusses how individuals with a healthy gut microbiome are better able to handle daily stressors. Unfortunately, research is still trying to conclude exactly what is most beneficial for how to fight anxiety and depression using the gut. Currently being studied is that pre- and probiotics might play an important role in helping the gut microbiome create all its products. Furthermore, reducing inflammation and improving integrity of the gut tight junctions also is showing promising results for improving symptoms of anxiety and depression.⁶

Inflammation and mental health

Another integral piece of gut health that affects mental health is the role of inflammation. Research has shown how stress, diet, and even antibiotic use can detrimentally affect the gut microbiome. This change in the gut microbiome is called gut dysbiosis. This gut dysbiosis ultimately causes increased levels of TNF-alpha, IL-6, monocyte chemoattractant protein, and other proteins. These neurotransmitters and cytokines are signs of inflammation and “leakiness” of the gut. When the gut has increased permeability, it allows more of the bad bacteria to pass through and further promote inflammatory processes. Studies are showing that certain strains of probiotics, including certain yeasts and bacteria, are able to decrease these inflammatory proteins and overall inflammation.⁷

Probiotics

Research studies have identified a few specific probiotic strains that assist individuals with anxiety or depression. One study discussed Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 specifically. This in human trial showed that, when these probiotic strains were taken simultaneously for at least 30 days, healthy participants reported improved anxiety and depression scores.⁸ Another trial in rats showed that the combination of Lactobacillus rhamnosus R0011 and Lactobacillus helveticus R0052 increased homeostasis of the gut microbiome, decreased gut permeability, and decreased production of pro-inflammatory TNF-alpha, IFN-gamma, and IL-17. For these reasons, many individuals who struggle with anxiety and depression have found that using probiotics containing Lactobacillus rhamnosus R0011, Bifidobacterium longum R0175, and Lactobacillus helveticus R0052 significantly aided in symptom reduction.⁹

Conclusion

Overall, the gut microbiome plays a significant role in promoting mental wellbeing. A healthy gut microbiome not only will create different neurohormones including serotonin, dopamine, GABA, and others, but the microbiome also creates vitamins for mood regulation as well. However, a gut that is suffering from dysbiosis will have increased permeability, decreased digestion efficacy, and ultimately increased inflammation. Daily nutrition significantly influences the gut microbiome and has been found to also affect mental wellbeing. Because of this finding, researchers are trying to understand how we can more naturally promote mental health through diet changes. This search has led to positive findings in very specific strains of probiotics. These probiotic strains improve gut microbiome health, improve inflammatory status, and ultimately decrease symptoms of anxiety and depression. If you’re looking to get more support for your gut health or anxiety, fill out this form and a member of our team with reach out to you.

Written by Amy Fohner, PharmD Candidate
Edited by Lindsey Dalton, PharmD

References:
1. Davenport ER, Sanders JG, Song SJ, Amato KR, Clark AG, Knight R. The human microbiome in evolution. BMC Biol. 2017;15(1):127. Published 2017 Dec 27. doi:10.1186/s12915-017-0454-7
2. Department of Health & Human Services. Gut health. Better Health Channel. Accessed January 29, 2024. https://www.betterhealth.vic.gov.au/health/healthyliving/gut-health.
3. Butler MI, Mörkl S, Sandhu KV, Cryan JF, Dinan TG. The Gut Microbiome and Mental Health: What Should We Tell Our Patients?: Le microbiote Intestinal et la Santé Mentale : que Devrions-Nous dire à nos Patients?. Can J Psychiatry. 2019;64(11):747-760. doi:10.1177/0706743719874168
4. Bear T, Dalziel J, Coad J, Roy N, Butts C, Gopal P. The Microbiome-Gut-Brain Axis and Resilience to Developing Anxiety or Depression under Stress. Microorganisms. 2021;9(4):723. Published 2021 Mar 31. doi:10.3390/microorganisms9040723
5. Appleton J. The Gut-Brain Axis: Influence of Microbiota on Mood and Mental Health. Integr Med (Encinitas). 2018;17(4):28-32.
6. Bear TLK, Dalziel JE, Coad J, Roy NC, Butts CA, Gopal PK. The Role of the Gut Microbiota in Dietary Interventions for Depression and Anxiety. Adv Nutr. 2020;11(4):890-907. doi:10.1093/advances/nmaa016
7. Clapp M, Aurora N, Herrera L, Bhatia M, Wilen E, Wakefield S. Gut microbiota’s effect on mental health: The gut-brain axis. Clin Pract. 2017;7(4):987. Published 2017 Sep 15. doi:10.4081/cp.2017.987
8. Messaoudi M, Violle N, Bisson JF, Desor D, Javelot H, Rougeot C. Beneficial psychological effects of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in healthy human volunteers. Gut Microbes. 2011;2(4):256-261. doi:10.4161/gmic.2.4.16108
9. Sarkar A, Lehto SM, Harty S, Dinan TG, Cryan JF, Burnet PWJ. Psychobiotics and the Manipulation of Bacteria-Gut-Brain Signals. Trends Neurosci. 2016;39(11):763-781. doi:10.1016/j.tins.2016.09.002