Watch the video

To view this content, consent for functional cookies needs to be given. Click this text to open the consent form.

Microbiome Dysbiosis

It is normal and healthy to have bacteria in the gut

A huge number of bacteria live in our guts. In fact, the average adult human is estimated to have 38 trillion (3.8 x 1013) bacteria living in their body, mainly in the digestive system. Ninety-seven percent of these bacteria are in the colon, whereas much lower numbers of bacteria are present in the stomach (107 bacteria) and small intestine (1011 bacteria).1

These bacteria are referred to as the gut microbiome, which is made up of more than 5,000 different types of bacteria.2 Together these bacteria produce a wealth of molecules as part of their metabolism, including vitamins, nutrients, and neurotransmitters.3,4 These molecules are called metabolites. Some metabolites are able to get into the human intestinal lining where they have local effects,5,6 while others enter the blood circulation and can affect organs such as the liver, or the brain.4,7

Good health requires a balance between our diet, the microbiome and our gut

A close relationship between the diet and the composition of the microbiome determines the types of metabolites being produced in the gut.3,8,9 A balanced relationship between diet, microbiome and human contributes to our well-being and long-term health.10,11,12,13

In some circumstances, the natural balance, or homeostasis, in the gut may be disturbed resulting in an unbalanced, or dysbiotic, microbiome14 with loss of diversity, overactivity of certain types of bacteria, or growth of harmful bacteria.15 Ultimately this may have negative consequences on our own health.16,17,18

Factors that may affect the balance of bacteria in your gut

Although the adult microbiome is relatively stable, it is sensitive to lifestyle factors such as diet,9 psychological stress,19 or medication.20 Use of antibiotics, for example, may cause an imbalance in the microbiome, and this effect could be long-lasting.21

Potential ways to maintain a healthy microbiome

Studies have shown that some probiotics may help maintain a healthy balance in the microbiome and reduce the risk of antibiotic-associated diarrhea. In these studies, two particular types of probiotics, called Bifidobacterium, BB-12® and Lactobacillus acidophilus, LA-5®, helped to reduce the length of time people experienced antibiotic associated diarrhea.22,23 One way that this may happen is when the probiotic bacteria compete with harmful bacteria, called pathogens, by producing substances that are toxic to these pathogens.24,25 

Beyond this, there are a range of ways in which probiotics have been shown to support a balanced microbiome:

  • Producing molecules with anti-bacterial effects, as shown by BB-12®,24 LA-5®,26 and Lactobacillus rhamnosus, LGG®27
  • Stimulating the body’s own anti-bacterial molecules, as shown by Lactobacillus paracasei, L. CASEI 431®28
  • Making it harder for pathogens to attach to the gut lining, as shown by BB-12®,29 LGG®,30 and Lactobacillus rhamnosus, GR-1®31 
  • Helping to physically displace adhering pathogens, as shown by LGG®32
In conclusion, probiotics could help to support a healthy, balanced microbiome, particularly when imbalances occur due to lifestyle factors or medications such as antibiotics.

BB-12®, LA-5®, LGG®, L. CASEI 431®, and GR-1® are registered trademarks of Chr. Hansen A/S.

The article is provided for informational purposes regarding probiotics and is not meant to suggest that any substance referenced in the article is intended to diagnose, cure, mitigate, treat, or prevent any disease.
 


Learn about the mode of action

Microbiome dysbiosis logo

Microbiome dysbiosis

Surviving stomach icon

Surviving the stomach

mucus layer logo

Mucus Layer

Immune system logo

Immune system

Intestinal barrier logo

Intestinal barrier

References Open Close

  1. Sender R, et al. Revised Estimates for the Number of Human and Bacteria Cells in the Body. PLoS Biol. 2016;14(8):e1002533. (PubMed)
  2. Rice BL, et al. Extensive Unexplored Human Microbiome Diversity Revealed by Over 150,000 Genomes from Metagenomes Spanning Age, Geography, and Lifestyle. Cell. 2019;176(3):649-662.e20.(PubMed)
  3. Yuan C, et al. Mucosal Microbiota and Metabolome along the Intestinal Tract Reveal a Location-Specific Relationship. mSystems. 2020;5(3):1–11. (PubMed)
  4. Morais LH, et al. The gut microbiota–brain axis in behaviour and brain disorders. Nat Rev Microbiol. 2021;19(4):241-255. (PubMed)
  5. Wong JMW, et al. Colonic health: Fermentation and short chain fatty acids. J Clin Gastroenterol. 2006;40(3):235–43. (PubMed)
  6. Yan F, et al. Soluble Proteins Produced by Probiotic Bacteria Regulate Intestinal Epithelial Cell Survival and Growth. Gasteroenterology. 2007;132(2):562–75. (PubMed)
  7.  Woodhouse C, et al. Modulating the gut – liver axis and the pivotal role of the faecal microbiome in cirrhosis. Clin Med (Lond). 2020;20(5):493–500. (PubMed)
  8. Tang W, et al. In vitro digestion and fermentation of released exopolysaccharides (r-EPS) from Lactobacillus delbrueckii ssp. bulgaricus SRFM-1. Carbohydr Polym. 2020;230:115593. (PubMed)
  9. Redondo-Useros N, et al. Microbiota and lifestyle: A special focus on diet. Nutrients. 2020;12(6):1–54. (PubMed)
  10. Fujimura KES, et al. Role of the gut microbiota in defining human health. Expert Rev Anti Infect Ther. 2010;8(4):435–54.(PubMed)
  11. Nicholson JK, et al. Host-Gut Microbiota Metabolic Interactions. Science. 2012;336:1262–1266. (PubMed)
  12. Ruan W, et al. Healthy Human Gastrointestinal Microbiome: Composition and Function After a Decade of Exploration. Dig Dis Sci. 2020;65(3):695–705. (PubMed)
  13. Kho ZY, Lal SK. The human gut microbiome - A potential controller of wellness and disease. Front Microbiol. 2018;9:1835. (PubMed)
  14. Hooks KB, O’Malley MA. Dysbiosis and its discontents. MBio. 2017;8(5):e01492-17. (PubMed)
  15. Berg G, et al. Microbiome definition re-visited: old concepts and new challenges. Microbiome. 2020; 8(1):103. (PubMed)
  16. Wilkins LJ, et al. Defining Dysbiosis for a Cluster of Chronic Diseases. Sci Rep. 2019;9(1):1–10. (PubMed)
  17. Petersen C, Round JL. Defining dysbiosis and its influence on host immunity and disease. Cell Microbiol. 2014;16(7):1024–33. (PubMed)
  18. Rogers GB, et al. From gut dysbiosis to altered brain function and mental illness: Mechanisms and pathways. Mol Psychiatry. 2016;21(6):738–48. (PubMed)
  19. Cryan JF, et al. The microbiota-gut-brain axis. Physiol Rev. 2019;99(4):1877–2013. (PubMed)
  20. Jackson MA, et al. Gut microbiota associations with common diseases and prescription medications in a population-based cohort. Nat Commun. 2018;9(1):2655. (PubMed)
  21. Palleja A, et al. Recovery of gut microbiota of healthy adults following antibiotic exposure. Nat Microbiol. 2018;3(11):1255-1265. (PubMed)
  22. Chatterjee S, et al. Randomised Placebo-controlled Double Blind Multicentric Trial on Efficacy and Safety of Lactobacillus acidophilus LA-5 and Bifidobacterium BB-12 for Prevention of Antibiotic-Associated Diarrhoea. J Assoc Physicians India. 2013;61:708–12. (PubMed)
  23. De Vrese M, et al. Probiotic lactobacilli and bifidobacteria in a fermented milk product with added fruit preparation reduce antibiotic associated diarrhea and Helicobacter pylori activity. J Dairy Res. 2011;78(4):396–403. (PubMed)
  24. Martins FS, et al. Comparative study of Bifidobacterium animalis, Escherichia coli, Lactobacillus casei and Saccharomyces boulardii probiotic properties. Arch Microbiol. 2009;191(8):623–30. (PubMed)
  25. Fooks LJ, Gibson GR. Mixed culture fermentation studies on the effects of synbiotics on the human intestinal pathogens Campylobacter jejuni and Escherichia coli. Anaerobe. 2003;9(5):231–42. (PubMed)
  26. Tabasco R, et al. Lactobacillus acidophilus La-5 increases lactacin B production when it senses live target bacteria. Int J Food Microbiol. 2009;132(2–3):109–16. (PubMed)
  27. Lu R, et al. Isolation, Identification, and Characterization of Small Bioactive Peptides From Lactobacillus GG Conditional Media That Exert Both Anti-Gram-negative and Gram-positive Bactericidal Activity. J Pediatr Gastroenterol Nutr. 2009;49:23–30. (PubMed)
  28. Cazorla SI, et al. Oral administration of probiotics increases Paneth cells and intestinal antimicrobial activity. Front Microbiol. 2018;9:736. (PubMed)
  29. Collado MC, et al. Role of commercial probiotic strains against human pathogen adhesion to intestinal mucus. Lett Appl Microbiol. 2007;45(4):454–60. (PubMed)
  30. Tytgat HLP, et al. Lactobacillus rhamnosus GG Outcompetes Enterococcus faecium via Mucus-Binding Pili: Evidence for a Novel and Heterospecific Probiotic Mechanism. Appl Environ Microbiol.2016;82(19):5756–5762. (PubMed)
  31. Petrova MI, et al. The lectin-like protein 1 in Lactobacillus rhamnosus GR-1 mediates tissue-specific adherence to vaginal epithelium and inhibits urogenital pathogens. Sci Rep. 2016;6:37437. (PubMed)
  32. Collado MC, et al. Protection mechanism of probiotic combination against human pathogens: In vitro adhesion to human intestinal mucus. Asia Pac J Clin Nutr. 2006;15(4):570–5. (PubMed)