stay updated with our newsletter

Close this search box.

Dispelling Common Myths and Misconceptions of Probiotics

With so many probiotics on the market now, it can be confusing as the best one to choose. Additionally, there are so many myths and misunderstandings associated with probiotics. How do practitioners know which ones to recommend for specific health benefits? Here are common myths and guidance that can be offered to your patients.

MYTH 1: All probiotic supplements are the same.

Probiotics have a specific naming classification system which is important in the determination of their characteristics and functionality.  Probiotics are identified by their specific strain, which includes the genus, the species, an alphanumeric strain designation, and a strain trademark (if applicable). The table below shows examples of the nomenclature used for commercial strains of probiotic organisms. Only at this level can a probiotic be evaluated for its efficacy, as the strain name indicates the research behind it and determines the quality of the probiotic.[1]

Genus Species Strain Strain Trademark
Pediococcus acidilactici CECT7483 KABPTM-021
Lactobacillus plantarum CECT7484 KABPTM-021
Lactobacillus plantarum CECT7485 KABPTM-021

MYTH 2: You do not need to worry about the probiotic strain – clinical studies on the species are close enough.

Differences in strain-specific efficacy began to be reported in 2010 as genomic analysis characterized bacterial and fungal strains in greater detail.[2] International probiotic guidelines and recognized experts in the field started to recommend using strain designations when reporting outcomes in clinical trials so that strain-specific efficacy can be determined, but this recommendation has not been uniformly followed.[3] Now DNA fingerprinting technology is being utilized as the gold standard for strain identification.

For example, the proprietary combination of three strains of lactic acid bacteria Lactobacillus plantarum CECT7484 (KABP-022), Lactobacillus plantarum CECT7485 (KABP-023), Pediococcus acidilactici CECT7483 (KABP-021) are specific strains identity verified using DNA-fingerprinting technology, and the benefits cannot be generalized to other combinations of the same species of bacteria.

Many products only specify the species contained, and not the strain. For example, a product may be labeled Lactobacillus plantarum, but whether the strain is Lactobacillus plantarum CECT7483 or any other Lactobacillus plantarum strain is unknown. So, it cannot be assumed it possesses 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 the studied potency.

Different strains of the same species can have different effects on health. Dietrich and colleagues compared two strains of the same species of L. casei. for the prevention of antibiotic-associated diarrhea (AAD). One strain was 1.3 times more effective in reducing AAD incidence than the other L. casei strain.[4]

A meta-analysis of 11 clinical trials (RCTs) studying various probiotics for the control of diabetes concluded that “probiotics may be used as an important dietary supplement in reducing the glucose metabolic factors associated with diabetes.”[5] However, when the data was re-evaluated, the analysis showed that no strain had a significant effect on diabetes parameters, which was contrary to the original meta-analysis conclusion.[6]

Selecting the right probiotic for each patient is complex and requires careful consideration of both the specific strains of probiotics and the health condition being treated. Additionally, safety is only assured at the strain level, emphasizing the importance of selecting strains that have been specifically studied for safety and efficacy.[7]

MYTH 3: More bacteria (higher Colony Forming Units) are always better.

Colony Forming Units (CFUs) represent the number of live and active microorganisms in a single serving of a probiotic dietary supplement. However, it is a common misconception that more CFUs are always better. A higher number of CFUs does not necessarily mean a more effective product. Some strains of bacteria can be effective in smaller quantities. Therefore, it is more important to look for a specific strain or combination of strains that have been clinically proven to provide the desired health benefits.

Additionally, some supplement companies will list the CFU count “at the time of manufacture.” However, because live organisms naturally degrade over time, it is more reliable to have the CFU count listed for the entire shelf life, as indicated by a “best by” date.

MYTH 4: All probiotics help symptoms of Irritable bowel syndrome (IBS).

IBS Irritable bowel syndrome (IBS) is a chronic disorder that results in a spectrum of gastrointestinal (GI) symptomatology and is characterized by abdominal pain, bloating, flatulence, and altered bowel habits. It affects 7%-15% of the general population, with the highest prevalence in South America (21%) and the lowest in South Asia (7%). Studies also show that IBS is slightly more common in females than in males.[8] With current available treatments having limited success, IBS significantly impacts the quality of life of those affected and presents a considerable cost burden for healthcare services.[9]

Lorenzo-Zúñiga and colleagues designed a clinical trial to specifically address the effect of a probiotic combination on IBS-related quality of life (IBS-QoL) utilizing the combination of three different strains: Lactobacillus plantarum CECT7484(KABP-022), Lactobacillus plantarum CECT7485(KABP-023), and Pediococcus acidilactici CECT7483 (KABP-021).[10]

Two different doses of this combination were administered to separate groups of subjects: a high dose (effective dose 10-30 billion CFUs per capsule) and a low dose (effective dose 3-6 billion CFUs per capsule). The proportion of the three strains was the same in both doses (1:1:1).

An interesting finding of the study is that this combination of three different probiotic bacteria strains             (identified as I.31 probiotics in the study), taken daily for six weeks, positively impacted IBS-related quality of life regardless of the probiotic dose. Although the higher concentration appeared to achieve a slightly faster improvement in IBS-QoL, with a significantly larger effect than the placebo group after three weeks, by the end of the study, no differences were observed between the concentrations in terms of quality of life or other measured parameters. This is unexpected because the higher concentration contained five times more viable probiotic cells than the lower concentration, suggesting a plateau effect may have been reached at the lower probiotic dose and further supports that more is not necessarily better when it comes to probiotics.

In a separate clinical trial, the same strain and combination of probiotics—Lactobacillus plantarum CECT7484 (KABP-022), Lactobacillus plantarum CECT7485 (KABP-023), and Pediococcus acidilactici CECT7483 (KABP-021)—were administered at a dose of one billion colony-forming units per strain for 4 weeks. The results demonstrated that this probiotic blend reduced diarrhea-related symptoms and supported the mental health and daily activities of healthy individuals under stress.[11]

These are examples of outcomes associated with a probiotic strain specific to the target group and health condition studied. Other strains of the same species cannot be linked to the same results.[12]  Care should be taken when selecting probiotics for patients with IBS symptoms. Although many species of probiotics can be beneficial in treating various IBS symptoms, interpreting trial results is challenging due to the lack of standardization in strains, dosages, treatment durations, and clinical outcome assessments. Choosing the appropriate probiotic for each patient requires careful consideration of the probiotic strain(s) and the specific disease indication.3

When it comes to probiotic selection, you should connect the strain to the science.

Many specialists now view probiotics as an effective way to modulate the microbiome for managing IBS. It is well-established that the gut microbiome’s composition is intrinsically linked to human health and significantly affects numerous medical conditions, especially gastrointestinal issues like IBS.[13] Thus, including a clinically studied probiotic in the treatment regimen for IBS patients is a sensible approach. This can profoundly improve the quality of life for those affected by IBS symptoms. The key to success lies in careful strain selection and ensuring that the chosen probiotic is backed by solid scientific evidence demonstrating its efficacy.



[1] Joint FAO/WHO (2002) Working Group Report on Drafting Guidelines for the Evaluation of Probiotics in Food: Ontario, Canada.

[2] Azaïs-Braesco V, Bresson JL, Guarner F, Corthier G. Not all lactic acid bacteria are probiotics, …but some are. Br J Nutr (2010) 103(7):1079–81. doi:10.1017/S0007114510000723

[3] McFarland, Lynne V., Charlesnika T. Evans, and Ellie JC Goldstein. “Strain-specificity and disease-specificity of probiotic efficacy: a systematic review and meta-analysis.” Frontiers in medicine 5 (2018): 124.

[4]  Dietrich CG, Kottmann T, Alavi M. Commercially available probiotic drinks containing Lactobacillus casei DN-114001 reduce antibiotic-associated diarrhea. World J Gastroenterol (2014) 20(42):15837–44. doi:10.3748/wjg.v20.i42.15837

[5] Sun J, Buys NJ. Glucose- and glycaemic factor-lowering effects of probiotics on diabetes: a meta-analysis of randomised placebo-controlled trials. Br J Nutr (2016) 115(7):1167–77. doi:10.1017/S0007114516000076

[6] McFarland LV. Importance of subgroup analysis in probiotic meta-analyses. Letter to the editor. Br J Nutr (2016) 116:375–6. doi:10.1017/S0007114516002026

[7] Shanahan F. A commentary on the safety of probiotics. Gastroenterol Clin North Am. 2012;41(4):869-876. doi:10.1016/j.gtc.2012.08.006

[8] Satish Kumar L, Pugalenthi LS, Ahmad M, Reddy S, Barkhane Z, Elmadi J. Probiotics in Irritable Bowel Syndrome: A Review of Their Therapeutic Role. Cureus. 2022;14(4):e24240. Published 2022 Apr 18. doi:10.7759/cureus.24240

[9] Corsetti M, Whorwell P. The global impact of IBS: time to think about IBS-specific models of care?. Therap Adv Gastroenterol. 2017;10(9):727-736. doi:10.1177/1756283X17718677

[10] Lorenzo-Zúñiga V, Llop E, Suárez C, et al. I.31, a new combination of probiotics, improves irritable bowel syndrome-related quality of life. World J Gastroenterol. 2014;20(26):8709-8716. doi:10.3748/wjg.v20.i26.8709

[11] Sato T, Honda S, Tominaga Y, Miyakoshi Y, Ueda T, Sawashita J. A probiotic blend improves defecation, mental health, and productivity in healthy Japanese volunteers under stressful situations. Heliyon. 2022;8(9):e10614. Published 2022 Sep 14. doi:10.1016/j.heliyon.2022.e10614

[12] McFarland LV, Evans CT, Goldstein EJC. Strain-Specificity and Disease-Specificity of Probiotic Efficacy: A Systematic Review and Meta-Analysis. Front Med (Lausanne). 2018;5:124. Published 2018 May 7. doi:10.3389/fmed.2018.00124

[13] Boyle RJ, Robins-Browne RM, Tang ML. Probiotic use in clinical practice: what are the risks? Am J Clin Nutr. 2006;83(6):1256-1447. doi:10.1093/ajcn/83.6.1256


Weekly round-up, access to thought leaders, and articles to help you improve health outcomes and the success of your practice.