THE ATHLETE MICROBIOME PART 1: Get to know your friendly microbes
The microbiome is a collection of trillions of commensal, symbiotic and pathogenic organisms (bacteria, fungi, viruses etc) that live within the human body (7). The microbiome can be a difficult aspect of the human body to grasp because it is invisible to the human eye. Part 1 of the athlete microbiome series will break down what your microbiome is, what factors influence the health of your microbiome and dysbiosis. Stay tuned for Part 2 where we will break down how the microbiome can influence athlete performance , recovery and energy availability.
As an athlete, trainer, coach or parent you may be interested in how to optimize performance, recovery and decrease risk of injury and sickness. Well you came to the right place. There is emerging evidence that the microbiota may factor into athlete health, performance, energy availability and inflammation (2). Keep in mind that nothing can replace the combined value of proper nutrition, sleep, stress management and physical therapies for athlete health. However, combining recent advances in microbiota research with our current knowledge of sports nutrition is the perfect recipe for the ultimate performance enhancement strategy.
→ Get to know your microbes
The microbiome is a vital and dynamic organ, yet the majority of athletes do not know it exists, nor how critical it is to overall health and well being. If the microbiome is a completely new subject to you, you are not alone - so keep reading.
The majority of bacteria that comprise our microbiome live within our large intestine, but can also be found in the vaginal canal, oral mucosa and on the skin (7). These bacteria are the conductors of many of the body's physiological processes such as metabolic processes, immune function, nutrient absorption and digestion (7). If that isn’t enough to spark some excitement, there is a bi-directional highway of communication that exists between our gut and our brain called the ‘gut-brain-axis’ (8). Communication on the gut-brain axis occurs primarily through the vagus nerve, neurotransmitters, neuropeptides and hormones (8). This phenomenon explains how the health of our gut can regulate mood disorders such as anxiety and depression (8).
So as you can see, the microbiome plays many roles and functions within the body. It is best to think about the microbiome as a complex ecosystem of organisms, just as you might think of an ecosystem such as a rainforest. Within a rainforest you have many different plants and other species that rely heavily on each other for the survival of the forest as a whole. The same theory applies to your microbiome- a collection of biological organisms that interact with each other as well as their environment.
An ecosystem like our microbiome, cannot survive without:
- Diversity: The diversity of species of bacteria that live within our microbiome is essential. Your microbiome can be broken down to respective phyla and bacterial species. The two main microbial phyla that reside within the microbiome are Firmicutes and Bacteroidetes (4). There are over 150 species of bacteria within the large intestine (4).
- Balance: Balance between species within an ecosystem is imperative to the overall survival of the host. We all witnessed what happened when we started losing our population of bees - let’s not go there (it still stings :D ) but seriously, when there is an imbalance between species of microbiota in the gut it can cause turmoil and subsequent damage to the host's health (YOU). We see disruptions in the balance between bacteria and overgrowth of pathogenic bacteria in chronic diseases (7).
- Hospitable environment: A habitable and hospitable environment is imperative for the health of our microbiome. The environment in which our microbiota reside can be influenced by genetics, and external factors such as stress, inflammation, nutrition and exposure to bacteria and pathogens (8). When we create an inhospitable environment through factors such as lifestyle and dietary choices, our microbial ecosystem cannot flourish.
When all three factors listed above are taken care of - all is well in the ecosystem. But the health of our microbial ecosystem is highly variable from host to host based on numerous factors (See Figure 1).
The evolution and development of our microbiota begins in the womb and starts to develop the moment we are born (6). Many studies have shown that how we are born (vaginal versus caesarean section) can impact our microbiome and thus health outcomes later in life (6).
The athlete microbiome is highly susceptible to bacterial imbalance due to poor dietary influences such as highly processed, inflammatory foods and sports drinks and supplements marketed to young athletes. Athletes have been shown to have a different microbial composition than non athletes. In a study published in the British Medical Journal, researchers discovered a significant difference in faecal microbial composition between elite athletes and sedentary individuals (1). This evidence supports the theory that exercise is beneficial for composition and function of the microbiota (1).
Figure 1: Factors which influence the human microbiome.
→ When the microbial ecosystem starts to fail
Dysbiosis is the term used to describe a microbiome that is poorly functioning, imbalanced and lacking diversity (8). On a day-to-day basis, common symptoms of dysbiosis can present as: gas, bloating, irregular stool (diarrhea/constipation), fatigue, anxiety, depression and mood changes (8). Think about that nice, plush, green rainforest turning into a grey, declining forest that has been plowed through by wildfires.
Athletes are particularly susceptible to disruptions in microbiota due to high stress training regimes leading to inflammatory processes and disruptions to gastrointestinal health (2). While your microbiome is up in flames, it cannot properly execute daily functions and support optimal body systems - potentially leading to poor immune function and overall health and performance.
Stay Tuned for the Athlete Microbiome PART 2- where we will be diving into how the microbiome can influence metabolic processes, energy availability and performance/recovery.
1. Barton, W., Penney, N. C., Cronin, O., Garcia-Perez, I., Molloy, M. G., Holmes, E., ... & O'Sullivan, O. (2018). The microbiome of professional athletes differs from that of more sedentary subjects in composition and particularly at the functional metabolic level. Gut, 67(4), 625-633.
2. Clark, A., & Mach, N. (2016). Exercise-induced stress behavior, gut-microbiota-brain axis and diet: a systematic review for athletes. Journal of the International Society of Sports Nutrition, 13(1), 1-21.
3. Lloyd-Price, J., Abu-Ali, G., & Huttenhower, C. (2016). The healthy human microbiome. Genome medicine, 8(1), 1-11.
4. Lloyd-Price, J., Mahurkar, A., Rahnavard, G., Crabtree, J., Orvis, J., Hall, A. B., ... & Huttenhower, C. (2017). Strains, functions and dynamics in the expanded Human Microbiome Project. Nature, 550(7674), 61-66.
5. Mohr, A. E., Jäger, R., Carpenter, K. C., Kerksick, C. M., Purpura, M., Townsend, J. R., ... & Antonio, J. (2020). The athletic gut microbiota. Journal of the International Society of Sports Nutrition, 17, 1-33.
6. Rutayisire, E., Huang, K., Liu, Y., & Tao, F. (2016). The mode of delivery affects the diversity and colonization pattern of the gut microbiota during the first year of infants' life: a systematic review. BMC gastroenterology, 16(1), 1-12.
7. Thomas, S., Izard, J., Walsh, E., Batich, K., Chongsathidkiet, P., Clarke, G., & Prendergast, G. C. (2017). The host microbiome regulates and maintains human health: a primer and perspective for non-microbiologists. Cancer research, 77(8), 1783-1812.
8. Weiss, G. A., & Hennet, T. (2017). Mechanisms and consequences of intestinal dysbiosis. Cellular and Molecular Life Sciences, 74(16), 2959-2977.
9. Van de Wouw, M., Schellekens, H., Dinan, T. G., & Cryan, J. F. (2017). Microbiota-gut-brain axis: modulator of host metabolism and appetite. The Journal of nutrition, 147(5), 727-745.