Exercise and the Gut Microbiome

“All disease begins in the gut.”
— Hippocrates

The Father of Modern Medicine

The ground-breaking teachings of Hippocrates often referred to as the father of Western medicine has influenced doctors from his time right up to the present day.

As such much of what Hippocrates said over two thousand years ago has stood the test of time, including the quote above.

However, not all disease begins in the gut. One could argue this does not apply to all infectious or genetic diseases, however there is evidence of chronic lifestyle disease originating in the gut. 

The human gut, the stomach and intestines, harbour over 100 trillion microorganisms referred to as the gut microbiota, gut flora or gut microbiomeThese microorganisms take up residence within the intestines shortly after birth and are vital to immune system development and supporting various neural functions.

The Evidence

There is evidence that many chronic conditions could be caused by microbial imbalance (dysbiosis) within the digestive tract where harmful bacteria or yeast overpopulate and affect the integrity of the gut lining leading to gut permeability (leaky gut). [1] When this happens, substances can leak from the digestive tract into the bloodstream [8], possibly triggering the immune system to attack its own cells and causing a chronic inflammatory response. According to numerous studies, this inflammation has been linked to serious disease, including obesity and insulin resistance [9].

Solutions to this problem often focus on improving dietary choices and taking supplements such as probiotics - but could exercise help too? Well, a research team at the University of Colorado found that activity at an early age can permanently alter the state of gut microbes for the better, promoting healthier brain and metabolic activity over a lifetime. Monika Fleshner, senior author of the study reported: 

“Exercise affects many aspects of health, both metabolic and mental, and people are only now starting to look at the plasticity of these gut microbes. That is one of the novel aspects of this research.”
— [2]

Positively altering the gut microbiome is one additional benefit of being active that may surprise you. The research didn't establish an exact age to start exercise, but the findings suggested the earlier, the better. 

Other recent studies have demonstrated that exercise can alter the gut microbiome and its diversity in a way that is beneficial to health and the benefits exist at all ages [3][4][5][6][7].

I believe that physical activity plays a critical role in health which is far more beneficial than an arbitrary choice to expend calories. Exercise activates anti-inflammatory and metabolic pathways that affect every system, including the gut and bacterial diversity, host metabolism and host immunity to promote health.


Read an earlier post on the importance of physical activity:



References:

[1] Vajro, Pietro, Giulia Paolella and Alessio Fasano. “MICROBIOTA AND GUT-LIVER AXIS: A MINI-REVIEW ON THEIR INFLUENCES ON OBESITY AND OBESITY RELATED LIVER DISEASE”, Journal of pediatric gastroenterology and nutrition (2013)

[2] Mika A, Fleshner M. "Early-life exercise may promote lasting brain and metabolic health through gut bacterial metabolites", Immunology and Cell Biology (2016) 

[3] Santacruz A, Marcos A, Warnberg J, Marti A, Martin-Matillas M, Campoy C et al. "Interplay between weight loss and gut microbiota composition in overweight adolescents." Obesity (2009) 

[4] Ringel-Kulka T, Cheng J, Ringel Y, Salojarvi J, Carroll I, Palva A et al. "Intestinal microbiota in healthy U.S. young children and adults—a high throughput microarray analysis." PLoS ONE (2013)

[5] O'Sullivan O, Cronin O, Clarke SF, Murphy EF, Molloy MG, Shanahan F, Cotter PD. "Exercise and the microbiota." Gut Microbes (2015)

[6] Clarke SF, Murphy EF, O'Sullivan O, Lucey AJ, Humphreys M, Hogan A, Hayes P, O'Reilly M, Jeffery IB, Wood-Martin R, et al. "Exercise and associated dietary extremes impact on gut microbial diversity." Gut (2014)

[7] Bermon S, Petriz B, Kajėnienė A, Prestes J, Castell L, Franco OL. "The microbiota: an exercise immunology perspective." Exerc Immunol Rev. (2015)

[8] Jialal I, Rajamani U. "Endotoxemia of metabolic syndrome: a pivotal mediator of meta-inflammation." Metab Syndr Relat Disord. (2014) 

[9] Escobedo G, López-Ortiz E, Torres-Castro I. "Gut microbiota as a key player in triggering obesity, systemic inflammation and insulin resistance." Rev Invest Clin. (2014)