Microbiome and Movement

Human body is made of trillions of cells, which group together to form different tissues and organs. But the humans are not entirely humans. The human body is host to many millions of microbes. In fact, microbes are the most numerous and diverse organisms on Earth. They are present everywhere, in the air, soil, plants, animals, under earth.Human body is an ecosystem and each of us carries an incredible diversity of microbes.

Human Microbiota and Human Microbiome:

Human microbiota is a community of microbes residing in and on human body. It consists of the 10-100 trillion symbiotic microbial cells harbored by each person, primarily bacteria in the gut.[1]. It refers to the entire population of microorganisms that colonizes a particular location; and includes not just bacteria, but also other microbes such as fungi, archaea, viruses, and protozoans.

Human microbiome is genes carried in that microbiota. The gut microbiota, has even been considered to be an “essential organ” , carrying approximately 150 times more genes than are found in the entire human genome.[2].

Chronic diseases such as obesity, inflammatory bowel disease,diabetes mellitus, metabolic syndrome, atherosclerosis, alcoholic liver disease, nonalcoholic fatty liver disease, cirrhosis have been associated with the human microbiota. Microbiome projects worldwide have been launched with the goal of understanding the roles that these symbionts play and their impacts on human health[2, 3].

Development of Microbiome:

Relation between the gut microbiota and human health is being increasingly recognized. It is now well established that a healthy gut flora is largely responsible for overall health of the host. The normal human gut microbiota comprises of two major phyla, namely Bacteroidetes and Firmicutes. [3].Though the gut microbiota in an infant appears haphazard, it starts resembling the adult flora by the age of 3 years. Nevertheless, there exist temporal and spatial variations in the microbial distribution from esophagus to the rectum all along the individual’s life span. Developments in genome sequencing technologies and bioinformatics have now enabled scientists to study these microorganisms and their function and microbe-host interactions in an elaborate manner both in healthy and disease states.

Function of gut microbiome:

The normal gut microbiota imparts specific function in host nutrient metabolism, xenobiotic and drug metabolism, maintenance of structural integrity of the gut mucosal barrier, immunomodulation, and protection against pathogens.[3]

Factors affecting the gut microbiome:

Several factors play a role in shaping the normal gut microbiota. They include: (1) Mode of delivery (vaginal or caesarean):- baby's first microbes primarily come from his or her mother's vaginal microbiome(the lactobacillus, which is a genus of bacteria containing many species that are important for human health) and for a newborn delivered by C-section,the baby's first microbes resembles like those microbes found on the human skin.

It is now seen that caesarean births are also associated with higher rates of a broad range of diseases, including asthma and food allergies. Some of these issues could be attributed to microbes. but it's an active area of research. 

(2) Diet during infancy (breast milk or formula feeds) and adulthood (vegan based or meat based):-beneficial bacteria in a baby's intestinal tract come directly from mother's milk, and from skin contact while breast feeding. Processed food lacks fibre and it suppreses gut microflora thereby causing allergies,inflammatory conditions.Plant based diet rich in fibre is good for gut flora.

(3) Use of antibiotics:- antibiotics can destroy the bad as well the good microbes and that it may take a year to recolonize the good microbes in the gut. Reduced variation in microbiota has been associated with these health problems, while increased diversity has been linked to a favorable metabolic profile and immune system response.

(4) Effect of environment on microbiota:- A clean, dirt free environment can destroy microbiome. Microbiome can be preserved and protected by avoiding harsh laundry products,antibacterial soaps and handwash,shampoo which target the skin and mouth microbiome.

(5)Effect of exercise on gut microbiota:- Exercise influences the gut microbiota,stimulating the development of gut bacteria.A major study conducted on elite rugby players demonstrated that exercise enriched the diversity of gut microflora(greater diversity among the Firmicutes phylum that helped to maintain a healthier intestinal environment) and positively correlated with protein intake and creatine kinase levels. These results indicated that both diet and exercise determined the microbial biodiversity of the gut. [6] Study published in Microbiome in 2016 shows that cardiorespiratory fitness is correlated with increased microbial diversity in healthy humans.The microbial profiles of fit individuals favor the production of butyrate. As increased microbiota diversity and butyrate production is associated with overall host health, the findings warrant the use of exercise prescription as an adjuvant therapy in combating dysbiosis-associated diseases.[7] Exposure to sunlight also alters the gut microbiome. A study showed that vitamin D deficiency changes intestinal microbiome,reducing the vitamin B production in the intestine,thereby adversely affecting immune system,causing pro-inflammatory state associated with autoimmunity and atherosclerosis.[5].So exercise and dietary Vitamin B and D supplementation can be used as therapeutic intervention in management of and inflammatory and autoimmune conditions.

Exercise  can be used as a treatment to maintain the balance of the microflora or to re balance eventual dysbiosis, thus obtaining an improvement of the health status. Further studies are needed to fully understand the mechanisms that determine changes in the composition and functions of the microflora caused by exercise and all their related effects. 

References:

(1)Ursell LK, Metcalf JL, Parfrey LW, Knight R. Defining the Human Microbiome. Nutrition reviews. 2012;70(Suppl 1):S38-S44. doi:10.1111/j.1753-4887.2012.00493.x.

(2)https://doi.org/10.1016/J.ENG.2017.01.008 The Human Microbiota in Health and Disease

[3] Manasa Jandhyala, Sai & Talukdar, Rupjyoti & Subramanyam, Chivukula & Vuyyuru, Harish & Sasikala, Mitnala & Reddy, Nageshwar. (2015). Role of the normal gut microbiota. World journal of gastroenterology : WJG. 21. 8787-803. 10.3748/wjg.v21.i29.8787.

[4] Monda V, Villano I, Messina A, et al. Exercise Modifies the Gut Microbiota with Positive Health Effects. Oxidative Medicine and Cellular Longevity. 2017;2017:3831972. doi:10.1155/2017/3831972.

[5]Vitamin D deficiency changes the intestinal microbiome reducing B vitamin production in the gut. The resulting lack of pantothenic acid adversely affects the immune system, producing a “pro-inflammatory” state associated with atherosclerosis and autoimmunity Gominak, S.C.Medical Hypotheses , Volume 94 , 103 - 107

[6]S. F. Clarke, E. F. Murphy, O. O'Sullivan et al., “Exercise and associated dietary extremes impact on gut microbial diversity,” Gut, vol. 63, no. 12, pp. 1913–1920, 2014. https://www.hindawi.com/journals/omcl/2017/3831972/

[7]T. Klaenhammer, E. Altermann, F. Arigoni et al., “Discovering lactic acid bacteria by genomics,” in Lactic Acid Bacteria: Genetics, Metabolism and Applications, pp. 29–58, Springer Netherlands, 2002. https://www.hindawi.com/journals/omcl/2017/3831972/