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What are probiotics?

- and what are the health benefits?

Professional lab technician analyzing probiotics
5 Min read

Probiotics are live bacteria that are associated with specific health benefits when consumed in the right amounts. To be classified as a probiotic, products must contain live bacteria, the live bacteria must have scientifically documented health benefits, and the product must contain a certain amount (CFU) of live bacteria.1 Specific probiotic strains have demonstrated benefits in many areas of health, including immune health, digestive health, women’s health, and oral health.


Probiotic bacteria must be alive when consumed in order to gain the associated health benefits, but the number of living bacteria in a product decreases over time because bacteria naturally die. Therefore, the number of bacteria reported on the product should be the number that will still be alive at the ‘end of shelf life’, and not the number that were alive on the date of manufacture, as the number will decrease between these two dates. 

What is the definition of a probiotic?

The World Health Organization has defined probiotics as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.1 Many foods and supplements contain live bacteria, but only bacterial strains with a scientifically demonstrated health benefit may be correctly termed probiotics. 

Fermented foods such as kimchi and sauerkraut contain live bacteria and have been associated with health benefits, but they are not considered probiotics as the health benefits were not demonstrated in human scientific studies, and the ‘adequate amount’ that must be consumed to gain the health benefit has not been determined.

Pharmacist and customer what are probiotics

Probiotic bacteria must be alive …

Probiotic products contain millions to billions of live bacteria. However, like any living organism, bacteria naturally die. Therefore, the number of live bacteria in a probiotic product will reduce between the date it was manufactured and the date it is purchased. The number of live bacteria is known as Colony Forming Unit (CFU).


… and the right amount must be consumed

As discussed, to be classified as a probiotic, the health benefits must be demonstrated in human scientific studies. The specific health benefit of each probiotic is then related to the amount (CFU) of live bacteria that was used to document its benefit. As the health benefit is only supported at that amount (CFU) of live bacteria, the documented amount should be consumed to gain the health benefit.2, 3

So, it is clear that: 

  • The number of bacteria naturally decrease over time, and 
  • Each probiotic strain must be consumed at a specific, pre-determined amount (CFU)

These two points mean that the number of bacteria (CFU) on the probiotic product’s potential expiry date (known as ‘end of shelf life’) is more important than the CFU on the date of manufacture.

Read more about what to look for when choosing a probiotic.

Genus, species, strain – does it matter? 

Yes, it does. 
Probiotics are identified through their genus, species, and strain. The strain is important as it is at this level that the probiotics have been studied, not at the more general level of genus or species.4
For example, the scientific results associated with the Chr. Hansen probiotic strain Lactobacillus rhamnosus, LGG® (hereafter referred to by use of the trademark LGG®) are primarily connected to digestive and immune health,5, 6, 7, 8 while the scientific results of Lactobacillus rhamnosus, GR-1® are primarily linked to women’s vaginal and urinary health.9, 10 Both of these strains are part of the Lactobacillus rhamnosus species, but it is the specific strain (i.e. the LGG® or GR-1® strain) that has been associated with study results and specific health benefits.

Probiotics may have benefits for human health

Probiotics have been scientifically studied for decades and have demonstrated benefits for different aspects of human health. Listed below are some examples of the health benefits that probiotic strains have been associated with.

Digestive system health 

In several scientific studies, supplementation with probiotic products containing the Chr. Hansen Bifidobacterium, BB-12® (hereafter referred to by use of the trademark BB-12®) strain has been associated with more regular bowel movements in adults who previously had irregular bowel movements,11, 12, 13 and with reduced incidence of crying and fussing in babies.14 Click to read more about probiotics and excessive crying and fussing in babies.


Immune health

Studies suggest that the immune health of babies and children may be positively affected following probiotic supplementation. The Chr. Hansen BB-12® and LGG® strains have been associated with fewer respiratory conditions,15, 16 fewer respiratory conditions lasting more than 3 days,7 significantly less days experiencing respiratory discomfort,7 and fewer conditions affecting the ear.16
Click to read more about probiotics and respiratory health.
Scientist analyzing probiotics

Urogenital health

Probiotic strains have also been associated with women’s urogenital health. For instance, scientific studies have associated the Chr. Hansen probiotic blend UREX (containing Lactobacillus rhamnosus, GR-1® and Lactobacillus reuteri, RC-14®) with benefits for urinary tract health9 and vaginal health.10, 17, 18, 19 

Oral health 

In children, consuming probiotic products containing the Chr. Hansen LGG® probiotic strain has been associated with benefits for oral health.20, 21

Key take-aways

When choosing a probiotic product, it is important to consider that: 

  • The health benefits of probiotic strains are specific to each particular probiotic strain and to the amount (CFU) of the probiotic strain that was investigated in the scientific studies.
  • The benefits observed are not generalizable to other health areas or strains.

Consult a health care professional to find out more about probiotics
For more information about our Chr. Hansen strains, click here.

BB-12®, GR-1®, LGG® and UREX 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.


References Open Close

  1. Hill C, et al. Nat Rev Gastroenterol Hepatol. 2014;11:506. (PubMed)
  2. Hoffmann DE, et alFood Drug Law J. 2014;69(2):237-ii. (PubMed)
  3. Jackson SA, et alFront Microbiol. 2019;10:739. (PubMed)
  4. McFarland LV, et al. Frontiers in medicine. 2018;5:124-. (PubMed)
  5. de Vrese M, et alJ Dairy Res. 2011;78(4):396-403. (PubMed)
  6. Pärtty A, et alThe Journal of Pediatrics. 2013;163(5):1272-7.e2. (PubMed)
  7. Hojsak I, et alPediatrics. 2010;125(5):e1171-7. (PubMed)
  8. Hojsak I, et alClin Nutr. 2010;29(3):312-6. (PubMed)
  9. Beerepoot MA, et al. Arch Intern Med. 2012;172(9):704-12. (PubMed)
  10. Petricevic L, et alEur J Obstet Gynecol Reprod Biol. 2008;141(1):54-7. (PubMed)
  11. Eskesen D, et al. Br J Nutr. 2015;114(10):1638-46. (PubMed)
  12. Uchida K, et al. Journal of Nutritional Food. 2005;8:39-51.
  13. Pitkala KH, et al. J Nutr Health Aging. 2007;11(4):305-11. (PubMed)
  14. Nocerino R, et al. Aliment Pharmacol Ther. 2020. (PubMed)
  15. Taipale T, et al. Br J Nutr. 2011;105(3):409-16. (PubMed)
  16. Rautava S, et al. Br J Nutr. 2009;101(11):1722-6. (PubMed)
  17. Martinez RC, et alLett Appl Microbiol. 2009;48(3):269-74. (PubMed)
  18. Vujic G, et al.Eur J Obstet Gynecol Reprod Biol. 2013;168(1):75-9. (PubMed)
  19. Anukam K, et alMicrobes Infect. 2006;8(6):1450-4. (PubMed)
  20. Nase L, et al. Caries Res. 2001;35(6):412-20. (PubMed)
  21. Glavina D, et alColl Antropol. 2012;36(1):129-32. (PubMed)
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