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The unseen role of microbiota for your gut health!

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  • NewDysbiosis of gut microbiota

Your microbiota is much bigger than you can imagine!

The human gastrointestinal tract is one of the largest surfaces in the human body, covering up to 400 m2.1 This is the equivalent to the size of two tennis courts! What’s more, covering this huge surface is the largest collection of microorganisms found anywhere in the human body!1

The human gut is home to almost 40 trillion microorganisms.
This is approximately 10 times more microbial cells than human cells!1

Bacteria make up the largest proportion of microorganisms (there are more than 1000 bacterial species found in the gut microbiota population, with ~60 predominant species)2,3, however there are also viruses and fungi.4

This collection of microorganisms is called microbiota.2


A healthy gut is influenced by its microbiota

The microbiota live in a mutually beneficial relationship with the gut.1 These helpful microbes can be found all along the gastrointestinal tract, but most are found within the large intestine.5 Very few are found within the stomach due to stomach acid, bile and secretions from the pancreas.5

This diverse collection of microorganisms helps with the normal functioning of the gut through various mechanisms, and there are different microorganisms that contribute to different health functions.1

Gut microbiota functions

  1. Contribute to energy and nutrient production including :
    • Fermentation of carbohydrates/sugars to produce substances that are used by the gut cells as an energy source6 ;
    • Digestion of proteins6 ;
    • Synthesis of vitamins such as Vitamin K and Vitamin B6 ;

Plus, there are even microbiota that ferment carbohydrates to provide an energy source for other beneficial microbiota in the gut!6


  1. Influence gut cell growth and renewal7 ;
  2. Help maintain a barrier which protects against pathogens7;
  3. Stimulate the immune system.

Furthermore, the gut mucus layer provides a place for the microbiota to grow, and in turn, the microbiota provide a physical barrier to keep harmful microbes from accessing the gut cells.7


A relationship starting at birth that leads to a unique, personal collection of microorganisms, called microbiota

The microbiota are introduced to the gut at birth, from exposure to the mother’s microbiota.8 The microbiota composition of an infant is also influenced by factors including mode of birth (C-section vs. vaginal delivery), gestational age (whether they were born full-term), breast-fed vs. bottle-fed, illness and exposure to medications.8 The microbiota composition fluctuates during these early years but reaches stability around 3 years of age.8

In adults the gut microbiota composition is well-established and relatively stable.1,9 In fact, each person’s microbiota is a very distinct and personal collection, and although it has been shown that there are predominant species common to all individuals, the composition and diversity can be influenced by a multitude of external factors throughout a person’s life.9

Diet is probably the biggest external factor that can influence microbiota composition.1 For example it has been found that people who have plant-based diets have more microbes that are involved in the fermentation of plant fibres compared with people who eat meat (who have greater numbers of microbes that degrade proteins).10 Where a person lives can also determine the dominant species of a person’s microbiota.11 This is because diets and lifestyles differ between cultures, which have a strong influence on the microbiota composition.11

(Internal code : 20.28)

Microbiota imbalance influences gut health in a negative way

While the world around us can have a positive influence on our microbiota, it can also have a negative impact.4 For example poor diet, illness and exposure to medications such as antibiotics can skew the microbiota population12,4. These drastic changes in microbiota can lead to reduced diversity and composition, which can have negative health consequences.13 This imbalance in diversity and composition is called intestinal dysbiosis.13  And for some factors such as antibiotics, the changes can persist for a long-time.13

Some probiotics has been demonstrated to restore balance to the microbiota when there is a disturbance.5,14 Taking probiotics is recommended by many gastroenterology societies to help maintain gut health and microbiota balance.5,15–18


Internal code : 20.40

Download our detailed sheets

  • NewDysbiosis of gut microbiota


  • 01 . Thursby E, Juge N. Introduction to the human gut microbiota. Biochemical Journal. 2017;474(11):1823-1836. doi:10.1042/BCJ20160510
  • 02 . Gilbert JA, Blaser MJ, Caporaso JG, Jansson JK, Lynch S V, Knight R. Current understanding of the human microbiome. Nature Medicine. 2018;24(4):392-400. doi:10.1038/nm.4517
  • 03 . Dore J, Tap J, Ehrlich D. Gut microbiota composition. In: Marteau P, Dore J, eds. Gut Microbiota: A Full-Fledged Organ. Paris: John Libbey Eurotext; 2017:13-23.
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  • 04 . Lozupone CA, Stombaugh JI, Gordon JI, Jansson JK, Knight R. Diversity, stability and resilience of the human gut microbiota. Nature. 2012;489(7415):220-230. doi:10.1038/nature11550
  • 05 . Guarner F, Sanders M, Eliakim R, et al. Probiotics and prebiotics. World Gastroenterology Organisation Global Guidelines. 2017:1-35.
  • 06 . Rowland I, Gibson G, Heinken A, et al. Gut microbiota functions: metabolism of nutrients and other food components. European Journal of Nutrition. 2018;57(1):0. doi:10.1007/s00394-017-1445-8
  • 07 . Tomas J, Sansonetti P. Host-microbiota dialog: interactions between the microbiota and the intestinal epithelium. In: Marteau P, Dore J, eds. Gut Microbiota: A Full-Fledged Organ. Paris: John Libbey Eurotext; 2017:55-64.
  • 08 . Butel M, Lepage P, Collignon A. Microbiota development: from the in utero period to the first few years of life. In: Marteau P, Dore J, eds. Gut Microbiota: A Full-Fledged Organ. Paris: John Libbey Eurotext; 2017:25-34.
  • 09 . Collignon A, Lepage P, Butel M. Gut microbiota evolution up to senescence. In: Marteau P, Dore J, eds. Gut Microbiota: A Full-Fledged Organ. Paris: John Libbey Eurotext; 2017:35-43.
  • 10 . David LA, Maurice CF, Carmody RN, et al. Diet Rapidly Alters the Human Gut Microbiota. Nature. 2014;505(7484):559-563. doi:10.1038/nature12820.Diet
  • 11 . Lepage P, Butel M, Collignon A. Factors modulating gut microbiota composition. In: Marteau P, Doré J, eds. Gut Microbiota: A Full-Fledged Organ. Paris: John Libbey Eurotext; 2017:45-53.
  • 12 . Rizkalla S, Dore J. Nutritional modulation of the gut microbiota. In: Marteau P, Dore J, eds. Gut Microbiota: A Full-Fledged Organ. Paris: John Libbey Eurotext; 2017:281-289.
  • 13 . Petersen C, Round JL. Defining dysbiosis and its influence on host immunity and disease. Cellular Microbiology. 2014;16(7):1024-1033. doi:10.1111/cmi.12308
  • 14 . Moré MI, Swidsinski A. Saccharomyces boulardii CNCM I-745 supports regeneration of the intestinal microbiota after diarrheic dysbiosis – A review. Clinical and Experimental Gastroenterology. 2015;8:237-255. doi:10.2147/CEG.S85574
  • 15 . Cruchet S, Furnes R, Maruy A, et al. The Use of Probiotics in Pediatric Gastroenterology: A Review of the Literature and Recommendations by Latin-American Experts. Pediatric Drugs. 2015;17(3):199-216. doi:10.1007/s40272-015-0124-6
  • 16 . Cameron D, Hock QS, Kadim M, et al. Probiotics for gastrointestinal disorders: Proposed Recommendations for children of the Asia-Pacific region. World Journal of Gastroenterology. 2017;23(45):7952-7964. doi:10.3748/wjg.v23.i45.7952
  • 17 . Malfertheiner P, Megraud F, O’Morain C, et al. Management of helicobacter pylori infection-the Maastricht V/Florence consensus report. Gut. 2017;66(1):6-30. doi:10.1136/gutjnl-2016-312288
  • 18 . Ghoshal UC, Gwee KA, Holtmann G, et al. The role of the microbiome and the use of probiotics in gastrointestinal disorders in adults in the Asia-Pacific region – background and recommendations of a regional consensus meeting. Journal of Gastroenterology and Hepatology (Australia). 2018;33(1):57-69. doi:10.1111/jgh.13840
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