The Microbiome – A Critical Player in Whole Body Health

By Jocelyn Antonelli, Nutrition Services Program Director, University of Notre Dame

Mar. 13, 2015; Jocelyn Antonelli – Food Services Administration. (Photo by Barbara Johnston/University of Notre Dame)

As we greet 2021 with renewed hope of turning the corner on this coronavirus pandemic, consideration for the health of our gut microbiome takes on added importance. The gut microbiome is emerging as one of the most important topics in the whole area of healing, prevention of disease and recovery. In fact, the microbiome being sometimes referred to as “the last undiscovered human organ” underscores its importance. Our gut bacteria regulate many of our bodily functions, from creating vitamins to controlling our immune system, our brain function, and even our metabolism and weight. Realizing that the choices we make with our forks on a daily basis either nurtures or neglects these little guys is a good mindset.

Our gut microbiome consists of hundreds of trillions of bacteria as well as viruses, fungi, and protozoa. There are up to 5,000 different species residing in our guts and collectively, they contribute 3 to 4 pounds to our overall body weight (Ferranti et al, 2014). These different species equal diversity, and that is an important concept. The microbiome is shaped by many factors from birth delivery method, infantile feeding method, antibiotic usage, stress, exercise, age, and diet. The balance of these microbes is important as some of them are beneficial and some of them are harmful. When the bad germs outweigh the good germs, we are in a state of dysbiosis. Dysbiosis can contribute to leaky gut, systemic inflammation, inhibition of detoxification, impaired immunity, and the development of various disease conditions (Vasquez, 2014). Therefore, it is important through our diet and lifestyle that we are feeding and nurturing the good guys.

The relationship we have with these microbes is symbiotic in that we provide them with food and a home, and they in turn do many important things for us. A very important benefit they provide, especially in the age of COVID, is modulation of the immune system. A very basic thing that we are beginning to understand is that 80% of the immune system resides in our intestinal lining. So it becomes extra important to tend to our gut in order to fortify our immune system. Another role these microbes play is extracting and synthesizing vitamins and nutrients from the foods we eat, notably vitamin K and several B vitamins. Although we can’t break down fiber and resistant starches, our microbiota can, and in return, they produce short chain fatty acids (SCFAs).  SCFAs produced by the intestinal microbiota are involved in gastrointestinal physiology, immune function, host metabolism, appetite suppression, and even in development and homeostasis of the central nervous system (Silva, Bernardi, & Frozza, 2020). In other words, a pretty important byproduct of the fiber we eat. Lastly, we know the microbiome plays an important role in our overall mood and level of cognitive functioning as the vast majority of our neurotransmitters are produced in our gut by these good germs. We used to think that all of our neurotransmitters were manufactured in the brain, and that was untrue. Enlightened psychiatrists are beginning to consider the role the microbiome plays in their patient’s mental health.

As Hippocrates once said, “all disease begins in the gut.” So how do we need to be feeding the good guys so that they stay healthy and in balance? First and foremost, we need a diet high in vegetables, fruit, and fiber; in other words, heavily plant-based. Because, as it turns out, amazingly, these good germs are vegan, i.e., they are plant eaters.  We need to eat a rainbow of different kinds of plants daily. The more species we consume, the better because the different populations of important germs eat different foods. We also need to increase our fiber. The average American only consumes 15 grams of dietary fiber per day, a far cry from the recommended 25 to 38 grams per day and dramatically less than the 100 to 150 grams our ancient ancestors consumed. Dr. Eric Alm of MIT found that adding just 10 more grams of dietary fiber each day led to 11% more diversity in our microbiota. And diversity is key as good health is tied to increased diversity in the microbiome.  Another dietary step is to increase consumption of probiotics and/or fermented foods such as miso, yogurt, kefir, sauerkraut, tempeh, kimchi, and kombucha. Dr. Justin Sonnenberg recommends trying to consume one of the above foods daily (Sonnenburg & Sonnenburg, 2016). Lastly, be mindful of sugar intake.  We know a diet high in sugar is detrimental to the good guys and instead caters to the microbes in our gut that we don’t want to thrive. Something I find really hopeful about our diets is that our microbiome is ultra-sensitive and positive changes with our food choices can lead to positive changes in our microbiome in as little as 24 hours!

Our microbiome is a miraculous arrangement in which these good germs play a tremendous role in our overall physical and mental wellbeing. Our knowledge in this field is rather new but growing at an exciting pace. What we eat and how we will live goes a long way in taking care of this delicate system. I like how Dr. Erica Sonnenburg invites us to think of our diet and microbiome in terms of the trillions of mouths we feed each day. Hopefully, that thought and image are added incentives to make better dietary choices.

References:Notre Dame Campus Dining

Ferranti, E., Dunbar, S., Dunlop, A., & Corwin, E. (2014). 20 Things you Didn’t Know About the Human gut Microbiome. J Cardiovasc Nursing, 6, 479-481. doi:10.1097/JCN.0000000000000166

Vasquez, A. (2014). Human microbiome and dysbiosis in clinical disease: An integrative functional medicine approach to understanding and treating microbial imbalances and chronic infections. United States: Alex Vasquez.

Silva, Y., Bernardi, A., & Frozza, R. (2020). The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication. Front. Immunol. doi:/10.3389/fendo.2020.00025

Sonnenburg, J., & Sonnenburg, E. (2016). The good gut: Taking control of your weight, your mood, and your long-term health. New York: Penguin Books.