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Myths and misconceptions about probiotics

 - addressing misunderstandings

Person checking myth and misconceptions of probiotics
5 Min read

The probiotics market is growing, but so with it are the number of misconceptions about probiotic products and their effects. In this article we highlight some of the more common probiotics misconceptions and try to address them.

  • Some probiotic strains have been extensively studied and their health benefits documented, but these benefits cannot be generalized to all probiotic products

  • The indicated bacteria need to be delivered in the right amount for the particular health area

  • Check which probiotic to use, check the specific strain and check the appropriate colony forming units (CFU) level

1) Are all probiotics the same?



The properties of probiotic strains are vastly dissimilar, resulting in a large variety of probiotic products with distinct documented effect or no documented effects. Many products only specify the species contained, and not the strain. For example, a product may be labelled Lactobacillus rhamnosus, but whether the strain is Lactobacillus rhamnosus, LGG®, the very different Lactobacillus rhamnosus, GR-1®, or any other Lactobacillus rhamnosus strain, is not known, and so neither is the documented potential health benefit. Further, clinically observed effects are associated with a specific potency and the probiotic product must be consumed live and at this potency.

2) Are probiotics with more bacteria the most effective?


Not necessarily 

A higher number of CFUs does not necessarily equal a superior effect. Instead, choosing a probiotic product at an appropriate CFU level, which is clinically associated with the desired effect is the best option. For example, Bifidobacterium, BB-12® has been associated with a increased defecation frequency in adults with constipation just as well at a dose of 1 billion CFU/day as with 10 billion CFU/day,1 whilst a beneficial effect of Lactobacillus, LGG® at a level of 10 billion CFU has been observed in several studies,2, 3 and therefore supplementation with Lactobacillus, LGG® at 10 billion CFU/day is often recommended, due to its association with reduced duration of gastroenteritis in infants and children.4

3) Do probiotic products with multiple strains have the most success?


Not necessarily

The number of strains in a probiotic product does not determine its functionality; the particular strain, the specific combination, and the clinical evidence is what should be considered, as many available multi-strain products lack clinical support for either the single strains they contain, or the combination of strains used. For example, Lactobacillus, LGG® as a single-strain product has been associated with beneficial immune system support,5, 6, 7 Lactobacillus rhamnosus, GR-1® and Lactobacillus reuteri, RC-14® in combination have been shown to help support urogenital health,8, 9, 10, 11, 12 and the combination of Bifidobacteria, BB-12®, Bifidobacteria infantis Bb-02 and Streptococcus thermophilus, TH-4® has been associated with reduced necrotizing enterocolitis in very preterm infants.13

Healthy family and probiotics

4) Do all fermented foods contain probiotic bacteria?



Since fermented foods are developed by using existing microbes or adding a live culture to a food, they contain live microbes. Often, however, a fermented food will go through further processing such as pasteurization, baking and filtering, thus killing the live microbes. Even if a fermented food does not go through one of these processes, it is still not necessarily termed a probiotic, as it may not have documented health benefits, or a specific potency associated with its consumption.

5) Do all yogurts contain probiotics?


Not all yogurts do

Yogurts can be a good source of probiotics but not all yogurts contain probiotics. All yogurts contain starter cultures (such as Streptococcus thermophilus and Lactobacillus bulgaricus), but only some yogurts include probiotic bacteria. Several yogurts have probiotic bacteria added together with the fermenting culture in order to ensure that the right amount of specific bacteria is present in the yogurt at the end of shelf life. Probiotic bacteria such as Bifidobacteria, BB-12®, Lactobacillus acidophilus, LA-5®, Lactobacillus rhamnosus, LGG® or Lactobacillus paracasei, L. CASEI 431® can be delivered in adequate amounts in yogurt which then qualifies the yogurt as a source of probiotic bacteria.

6) Can probiotic products be used whilst taking antibiotics?



Probiotics can help restore the microbiota when negatively affected by antibiotic use. Probiotcs may also be able to help address potential side effects of antibiotics  - Lactobacillus rhamnosus, LGG® has been associated with reducing the frequency of antibiotic-associated diarrhea,14, 15 whilst combining antibiotic treatment with Lactobacillus rhamnosus, GR-1® and Lactobacillus reuteri RC-14® has been associated with improved result with respect to bacterial vaginosis, compared to treatment with antibiotics alone.8, 16 When combining antibiotic treatment with probiotic supplementation, it is recommended that the probiotics are taken a few hours after the antibiotics in order to optimize the effect.

7) Have probiotic strains been clinically studied?


Yes, some have

The clinical effect of some different probiotic strains has been studied in human clinical trials; however, these results cannot be extrapolated to all probiotic strains and products, therefore, caution must be exercised when choosing a probiotic product.

Click to read more about what to look for when choosing a probiotic product

 You can also read about the extensively studied Chr. Hansen strains here.

8) Is it common to isolate probiotic strains from various sources?


Remember that probiotic strains are bacteria, entirely separate entities in the classification of all living organisms17. It is also important to first establish that probiotic strains are microorganisms that can live in a variety of areas, and the source of the isolation does not determine what comprises the microorganism, nor do they bring with them any component of where they are found and/or isolated from.

Humans are born without a microbial population, and the resident microbes of any individual develop throughout different stages of life. For example, the microbiome can be seeded from a mother to an infant during vaginal delivery, and further impacted through breastfeeding and later exposure to foods, people and the environment. The microorganisms found in humans co-exist with us and take up residence in a niche that supports their growth until they move along and inhabit another host, or environment, or food.

Thus, the isolation source of probiotic strains is varied in nature, reflecting the diversity of environments from which humans are exposed to beneficial bacterial. With that in mind, commonly seen isolation sources for probiotics include human intestinal (more commonly in the form of a feces sample) and vaginal samples, environmental samples and various food sources, such as fermented dairy products and other naturally fermented food sources.


9) Are probiotic strains isolated from humans more ideal for human consumption?


Reputable international scientific organizations have never considered that the "origin" of a strain is a prerequisite for probiotic benefits. The World Health Organization (WHO) defines probiotics as "live microorganisms that, when administered in adequate amounts, confer a health benefit on the host"18. Nowhere in the probiotic definition is origin mentioned. In addition, the International Scientific Association for Probiotics and Prebiotics (ISAPP) states that "a high-quality, effective probiotic does NOT have to be" naturally found in the human gut or "human-derived"19.

What is important to remember is that human health benefits have been established for probiotic strains isolated from plants, foods, human feces, animals, and other sources. With regards to choosing probiotics with supporting health benefits, it is more important to rely on the safety of the proven science and clinical documentation on the strains rather than to focus on their origin of isolation. In other words, proving that a microbial culture is safe and efficacious through science is what makes a probiotic, not where it was isolated from.

Click to read more about Chr. Hansen’s probiotic strains, some of the world’s most documented.


10) Many consumers today prefer to buy more natural products. Can probiotic strains isolated from humans be considered more "natural" than ones isolated from other sources?



Probiotic strains are bacteria that can be found in every habitat on Earth20. As such, there is no agreed-upon definition what constitutes a "natural" probiotic in the way that it is understood from most consumers’ perspectives.


As mentioned above, humans are born without a resident microbial community, and rather acquire microbes throughout different life-stages through contact with other people and the environment, and foods that are eaten. In fact, the human body is constantly exposed to bacteria from a variety of sources, and this diversity is an important component of a healthy intestinal microbiome, especially when you consider the evidence of disease incidence being reduced in populations that have pets, siblings or live with animals (i.e., more rural settings)21,22.

Again, independent of the isolation source, what is critical is that the microbial culture being consumed as a probiotic has been shown to provide a health benefit on the host, while also possessing required safety parameters. In fact, there is a multitude of probiotic strains not isolated from humans that have been demonstrated to show benefits on human health.


LGG®, GR-1®, BB-12®, RC-14®, TH-4®, and L.CASEI 431® 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.Eskesen D, et al. Effect of the probiotic strain Bifidobacterium animalis subsp. lactis, BB-12®, on defecation frequency in healthy subjects with low defecation frequency and abdominal discomfort: a randomised, double-blind, placebo-controlled, parallel-group trial. Br J Nutr. 2015;114(10):1638-46. (PubMed)
2.Isolauri E, et al. A human Lactobacillus strain (Lactobacillus casei sp strain GG) promotes recovery from acute diarrhea in children. Pediatrics. 1991;88(1):90-7. (PubMed)
3.Sindhu KN, et al. Immune response and intestinal permeability in children with acute gastroenteritis treated with Lactobacillus rhamnosus GG: a randomized, double-blind, placebo-controlled trial. Clin Infect Dis. 2014;58(8):1107-15. (PubMed)
4.Merenstein D, et al. World Gastroenterology Organisation Global Guidelines - Probiotics and prebiotics. World Gastroenterology Organisation. 2017.
5.Davidson LE, et al. Lactobacillus GG as an immune adjuvant for live-attenuated influenza vaccine in healthy adults: a randomized double-blind placebo-controlled trial. Eur J Clin Nutr. 2011;65(4):501-7.(PubMed)
6.Hojsak I, et al. Lactobacillus GG in the prevention of nosocomial gastrointestinal and respiratory tract infections. Pediatrics. 2010;125(5):e1171-7. (PubMed)
7.Hojsak I, et al. Lactobacillus GG in the prevention of gastrointestinal and respiratory tract infections in children who attend day care centers: a randomized, double-blind, placebo-controlled trial. Clin Nutr. 2010;29(3):312-6. (PubMed)
8.Anukam K, et al. Augmentation of antimicrobial metronidazole therapy of bacterial vaginosis with oral probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14: randomized, double-blind, placebo controlled trial. Microbes Infect. 2006;8(6):1450-4. (PubMed)
9.Beerepoot MA, et al. Lactobacilli vs antibiotics to prevent urinary tract infections: a randomized, double-blind, noninferiority trial in postmenopausal women. Arch Intern Med. 2012;172(9):704-12. (PubMed)
10.Martinez RC, et al. Improved treatment of vulvovaginal candidiasis with fluconazole plus probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14. Lett Appl Microbiol. 2009;48(3):269-74. (PubMed)
11.Petricevic L, et al. Randomized, double-blind, placebo-controlled study of oral lactobacilli to improve the vaginal flora of postmenopausal women. Eur J Obstet Gynecol Reprod Biol. 2008;141(1):54-7. (PubMed)
12.Reid G, et al. Nucleic acid-based diagnosis of bacterial vaginosis and improved management using probiotic lactobacilli. J Med Food. 2004;7(2):223-8. (PubMed)
13.Jacobs SE, et al. Probiotic effects on late-onset sepsis in very preterm infants: a randomized controlled trial. Pediatrics. 2013;132(6):1055-62. (PubMed)
14.Arvola T, et al. Prophylactic Lactobacillus GG reduces antibiotic-associated diarrhea in children with respiratory infections: a randomized study. Pediatrics. 1999;104(5):e64. (PubMed)
15.Vanderhoof JA, et al. Lactobacillus GG in the prevention of antibiotic-associated diarrhea in children. The Journal of Pediatrics. 1999;135(5):564-8. (PubMed)
16.Martinez RC, et al. Improved cure of bacterial vaginosis with single dose of tinidazole (2 g), Lactobacillus rhamnosus GR-1, and Lactobacillus reuteri RC-14: a randomized, double-blind, placebo-controlled trial. Can J Microbiol. 2009;55(2):133-8. (PubMed)
17.Taxonomy - Five-Kingdom Classification, Prokaryotic Monera, and Multitissued Organisms | Britannica
18. Hill, C. et al.Nat. Rev. Gastroenterol. Hepatol 11, 506–514 (2014).
20. Bacteria | What is microbiology? | Microbiology Society
21. Tun, H.M., Konya, T., Takaro, T.K. et al. Exposure to household furry pets influences the gut microbiota of infants at 3–4 months following various birth scenarios. Microbiome 5, 40 (2017).
22. Laursen MF, Zachariassen G, Bahl MI, Bergström A, Høst A, Michaelsen KF, Licht TR. Having older siblings is associated with gut microbiota development during early childhood. BMC Microbiol. 2015 Aug 1;15:154. doi: 10.1186/s12866-015-0477-6. PMID: 26231752; PMCID: PMC4522135.
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What to 
look for

See key tips on how to choose a high-quality probiotic product


Learn how to review the evidence when considering probiotic strains and effects


Read more about some of the world’s most documented probiotic strains and their diverse, beneficial health effects

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