You’ve probably heard people say that a healthy gut equals a healthy mind. But what does this actually mean and what can we learn from this in the time of COVID-19? According to a survey from the Census Bureau and the Centers for Disease Control and Prevention, about a third of Americans have reported recent symptoms of anxiety and depression since late April 2020. We are obviously experiencing more symptoms of anxiety and depression this year than in past years.

What is a Healthy Microbiome?

A meeting of the North American branch of the International Life Sciences Institute (ILSI) conference was held specifically to try to answer this question. They concluded that “…diversity is likely more important than the presence of specific taxa.” In other words, a microbiome with high diversity is a healthy microbiome. Then the question becomes, how do we promote a diverse, healthy microbiome?

 

How is a Healthy Microbiome Related to Our Mental Health?

One approach is to mind our microbiome-gut-brain axis. It is becoming clear that the human microbiome (i.e., the collection of all the microorganisms, including eukaryotes, archea, bacteria, viruses, and fungi, living in association with the human body) plays a role in human health and well-being, including mental health. A number of hypotheses have been put forward to explain the impact of microbial exposures on human health, including the “Hygiene Hypothesis,” “Missing Microbes Hypothesis,” “Biodiversity Hypothesis,” and the “Old Friends Hypothesis”. What these hypotheses all have in common is the understanding that humans require diverse microbial exposures for optimal health, including optimal mental health.

The “Old Friends” that confer health benefits to humans have been classified into three different categories: (i) the commensal microbiota (i.e., those microbes that are normally found on and in the human body); (ii) pathogens associated with the “old infections” that were present throughout life in evolving human hunter-gatherer populations; and (iii) organisms from the natural environment that humans were in daily contact with throughout human evolution. Exposure to these “Old Friends” is thought to increase stress resilience in part by keeping inflammation under control, and thus reducing the risk of overt inflammatory disease, but also reducing the risk of anxiety disorders, trauma- and stressor-related disorders such as post-traumatic stress disorder (PTSD), and affective disorders, conditions in which inflammation has been identified as a risk factor.

What You Can Do Today to Promote a Healthy Microbiome-Gut-Brain Axis

There are a few things you can do to promote a healthy microbiome.

• Increase contact with natural environments (e.g., by engaging in regular physical exercise outdoors, while following CDPHE Guidelines, and following a healthy diet such as a traditional Mediterranean diet).
• Consume probiotic bacteria in fermented foods (e.g., kefir, kimchi, kombucha, miso, sauerkraut, tempeh, and yogurt) or other preparations.
• Consume prebiotics (i.e., indigestible fiber, such as found in many plants, or psyllium flakes), which can promote expansion of beneficial bacteria.
• Use antibiotics only in cases of true need.
• Support breastfeeding, with solid foods from 4-6 months onwards.
• Do not avoid exposure to environmental allergens (foods, pets), if not proven necessary.
• Do not smoke.

Although the risks to our mental health are high in the time of COVID-19, promoting a diverse, healthy microbiome is one approach to optimizing stress resilience and decreasing risk of stress-related mental health conditions.

Christopher A. Lowry, PhD
Associate Professor, Department of Integrative Physiology
University of Colorado Boulder
Department of Physical Medicine and Rehabilitation and Center for Neuroscience,
University of Colorado Anschutz Medical Campus

Dr. Neill Epperson and Dr. Christopher Lowry discuss how having a healthy microbiome is important to your mental health.

References

Sonnenburg ED, Sonnenburg JL. Starving our microbial self: The deleterious consequences of a diet deficient in microbiota-accessible carbohydrates. Cell Metab 2014;20:779-786.

Sonnenburg JL, Sonnenburg ED. Vulnerability of the industrialized microbiota. Science 2019;366.

von Hertzen L, Beutler B, Bienenstock J et al. Helsinki alert of biodiversity and health. Ann Med 2015;47:218-225.

Atherton JC, Blaser MJ. Coadaptation of Helicobacter pylori and humans: Ancient history, modern implications. J Clin Invest 2009;119:2475-2487.

Rook GA, Raison CL, Lowry CA. Microbial 'old friends', immunoregulation and socioeconomic status. Clin Exp Immunol 2014;177:1-12.

McBurney MI, Davis C, Fraser CM et al. Establishing What Constitutes a Healthy Human Gut Microbiome: State of the Science, Regulatory Considerations, and Future Directions. J Nutr 2019;149:1882-1895.

Mind the Brain CME Information: 
CME Survey for the July 28, 2020 Edition

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