By Diana Koklonis, Clinical Account Team Manager at Optibac Probiotics. Bachelor in Nutrition and Dietetics (Hons), MSc in Food, Nutrition and Metabolism

Written in collaboration with the healthcare professional support team at Optibac Probiotics.

Probiotics in gut disorders management: frequently asked questions in clinical settings

Gastrointestinal disorders are characterised by an irregularity involving an imbalanced bacterial composition of the gut microbiome, known as dysbiosis(1). Probiotics have long been shown to exhibit high potential therapeutic effects in managing some of these conditions through different mechanisms, including modifying the gut microbiota (1,2,3,4).

Three of the most common gastrointestinal conditions seen in both primary and secondary care are Antibiotic Associated Diarrhoea (AAD)/Acute Diarrhoea (AD), Irritable Bowel Syndrome (IBS), and Functional Constipation (FC) (5,6,7,8,9). However, the application of probiotic’s benefits in clinical practice remains a challenge due to conflicting and limited guidelines.

What has research shown regarding the efficacy of probiotics?

Systematic reviews and meta-analyses have consistently demonstrated the growing body of evidence supporting the efficacy of probiotics in managing specific gut conditions and alleviating symptoms. It’s important to recognise that this efficacy is highly dependent on the specific probiotic strain and the particular disease or condition being addressed. Considering this strain, and disease specificity, is essential in clinical practice and healthcare professionals should be mindful of these factors when recommending probiotics to their patients (10).

Probiotics work in a strain-specific way. What does it mean?

probiotics - mechanisms of action

Do GPs and other Healthcare Professionals (HCPs) recommend probiotics?

While some HCPs are more informed about the clinical evidence supporting probiotics, there is still variability in recommendations across different guidelines. Some guidelines acknowledge the benefits of probiotics in specific conditions, while others call for more research. There is also a lack of consideration for strain specificity and the number of responders in some of these guidelines, which can lead to HCPs being unaware of how/when to include probiotics in the clinical practice; especially with individuals who might need a more unique approach/assessment in specific clinical cases. In fact, a cross sectional survey found that 72% of HCPs were likely to recommend a probiotic, but still the vast majority, with 91% of respondents, mentioned a need for more education (11).

Frequently asked questions (FAQ) in clinical settings include:

  • If effectiveness is strain specific, what strains are recommended in GI disorders?
  • What probiotic strains are recommended for antibiotic associated diarrhoea (AAD), acute diarrhoea, C.difficile infection, IBS and constipation?
  • What dosage? What format? Duration of supplementation?


  • Are probiotics safe?
  • What about vulnerable patients?
  • Is there any research on tube fed patients and ICU?

Let’s discuss all of these FAQ:

What strains are recommended for GI disorders:

As a group, probiotics have demonstrated significant improvements in different GI disorders. In IBS, they have shown to reduce global symptoms and/or abdominal pain in at least 50% of individuals (5,12). In AAD, they have been shown to reduce the risk from 37% up to 55%, especially in individuals at higher risk who seemed to drive more positive results(13,14). In functional constipation, probiotics have been shown to improve stool frequency, stool form and/or consistency in up to 50% of individuals (15,16).


Meta-analyses have shown that probiotics may provide a moderate effect for preventing AAD. Probiotics S.boulardii, L. acidophilus and L.casei were the three most consistently effective species for AAD (13,14,17). Strains with stronger evidence include Saccharomyces boulardii CNCM I-745, a three-strain mixture (L. acidophilus CL1285, L. casei Lbc80r, L. rhamnosus CLR2) and L. casei DN114001. Other acidophilus strains that have shown significant results in lowering the incidence and duration with grade 1 evidence include L. acidophilus NCFM (18) ,and L. acidophilus Rosell®-52 extensively researched for AAD.


Different meta-analyses have shown that some probiotic strains are useful in reducing the severity and duration of AD in children and adults. Saccharomyces boulardii (SB) is one of the best-studied probiotics in both (19)., reducing duration and risk of persistence regardless of its cause (bacteria, virus, or protozoa) (20,21).

It reduces diarrhoea duration and hospitalisation in adults and children by about 1 day(20,21) . Additionally, SB reduces the consequences of gastrointestinal infections by helping restore intestinal fluid transport (22,23). Other significant results include a reduction in stool frequency (2.2/day vs 4.01 control) and significant improvement of stool consistency(24,25). (normal in 76% of participants by day 3)(25). Furthermore, a meta-analysis reported a reduced risk of diarrhoea lasting >7 days (RR 0.25) (20).


Studies have shown that SB could almost halve the number of primary cases and recurrences of CDI(26,27). The effect seems to be 67% more effective in patients with a previous history of CDI and treated with a high dose of vancomycin(26). However, more studies are needed to evaluate this further.


Recent guidelines and some meta-analyses have not been able to identify which specific strains or particular combinations are likely to be effective(3,5,12). However, a more recent meta-analysis have reported a number of different strains more likely to be effective(28). They include:

table comparing probiotics


Meta-analyses and systematic reviews have different findings for functional constipation, but recommendations remain to focus on probiotic strains with gold standard studies that have shown a clinical efficacy in reducing whole gut transit time and/or improving stool consistency and frequency(15,16) Some probiotic strains showing positive results are:

  • Bifidobacterium animalis subsp. Lactis HN019
  • Bifidobacterium. lactis bi-07
  • Bifidobacterium animalis  DN-173010
  • Bifidobacterium lactis bb-12 29

Multi-strain or single strain? Duration of supplementation?

Grouping all multi-strain probiotics or all single-strain probiotics together mixes up the data rather than helping determine the effect of specific probiotics, and that is why this focus creates controversy. Different systematic reviews and meta-analyses have reached different conclusions, with some recommending the use of single strains and some multi-strains, depending on the condition(3,28,30).

Nevertheless, probiotics are efficacious at a taxonomic level (strain)(10,13), and rather than focussing on administering multiple strains from different genus, attention should be on the proven strain-specific effectiveness and established safety profile.

What timeframe/ dosage/ format?

Timeframe: Given the complexity of the human gut microbiome, it remains reasonable to advise taking probiotics for at least up to 12 weeks, as studies suggest that the timeframe for improvement varies from 8 to 16 weeks. If there is no improvement in symptoms after this period, it should be recommended to switch to a different probiotic(5,31,32). Colonisation of probiotics in the gut is transient, however, benefits could still be seen after cessation of the probiotic administration. Therefore, an individual approach is recommended.

Dosage: The dose of probiotic supplementation varies greatly between clinical studies, and these are not comparable. Recommendations should be based on the strains and dosage used in clinical trials that achieved efficacy.

Format: Recommendation should be based on the strains that have shown to be stable for the duration of the shelf life and that reach the gut alive.


Different meta-analyses and systematic reviews have confirmed the safety, efficacy and significance of probiotics in different GI disorders like IBS, functional constipation, AAD and others (15,16,19,28).

Caution should be considered for certain at-risk populations, such as immunocompromised individuals, those with a serious illness, those with ‘short gut’, or with central catheters – there could be a higher risk of catheter contamination especially when probiotic format comes in a powder form(33).

For autoimmune conditions, probiotics have been typically used in some studies and case reports, but they should be taken cautiously with immunosuppressant medication and in individuals with an active immune condition. There is more research needed to achieve a better understanding(34,35,36,37,38,39). It is also recommended to ensure caution is taken for their use in individuals with severe leukopenia and/or risk of bacterial translocation. It’s crucial to base decisions on clinical reasoning.

For patients in the ICU and tube fed, each hospital usually follows an internal/regional guideline. Adhering to protocols and/or consent from the attendant physician is advised.  For guidance, different meta-analysis and systematic reviews do show the protocol that was followed, safety rates and efficacy. It is worth to notice that a recent meta-analysis considered probiotics a safe nutritional intervention among vulnerable patients(40),but individual safety assessment and care should be supported. This is by no means a recommendation or advice, but rather an update on scientific literature. Protocol decisions should be made by the medical team.


Gastrointestinal disorders symptoms management still remains a challenge in primary and secondary care with a need of more research and guidelines to clinically assess and approach the management of a variety of conditions including AAD/AD, IBS and functional constipation.

Probiotics have long been studied and proven to exert beneficial effects by helping improve a diversity of symptoms such as abdominal pain, diarrhoea, constipation, bloating and others through microbiota modulation. Nonetheless, probiotics work in a strain and disease specific manner and healthcare professionals should be mindful of these factors when recommending probiotics to their patients.

More education and guidelines of probiotics use in clinical settings are still essential, as insufficient knowledge seems to be a limiting reason of HCPs recommending probiotics and in patients receiving evidence-based information and recommendations, especially in certain at-risk populations.


Written in collaboration with the healthcare professional support team at Optibac Probiotics.

Optibac logo

Disclaimer: This blog has been developed in association with the healthcare professional support team at Optibac Probiotics. Approval of each sponsor and activity is carefully assessed for suitability on a case by case basis. Sponsorship does not imply any endorsement of the brand by MyNutriWeb, its organisers, its moderators or any participating healthcare professional, or their association. Sponsorship funds are reinvested into the creation and promotion of professional development opportunities on MyNutriWeb.


Probiotics in the Management of of Gut Disorders – Webinar