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Statistical considerations for the design of randomized, controlled trials for probiotics and prebiotics

/in ISAPP Science Blog /by KC

By Prof. Daniel Tancredi, UC Davis, USA

The best evidence for the efficacy of probiotics or prebiotics generally comes from randomized controlled trials. The proper design of such trials should strive to use the available resources to achieve the most informative results for stakeholders, while properly accounting for the consequences of correct and incorrect decisions. It is crucial to understand that even well-designed and -executed studies cannot entirely eliminate uncertainty from statistical inferences. Those inferences could be incorrect, even though they were made rigorously and without any procedural or technical errors. By “incorrect”, I mean that the decisions made may not correspond to the truth about those unknown population parameters. Those parameters involve the distribution of study variables in the entire population, but our inferences are inductive and based on just the fraction of the population that appeared in our sample, creating the possibility for discordance between those parameters and our inferences about them. Although rigorous statistical inference procedures can allow us to control the probabilities of certain kinds of incorrect decisions, they cannot eliminate them.

For example, consider a two-armed randomized controlled trial designed to address a typical null hypothesis, that the probability of successful treatment is the same for the experimental treatment as for the comparator. Depending on the analytical methods to be employed, that null hypothesis could also be phrased as saying that the difference in successful treatment probabilities between the two arms is zero or that the ratio of the successful treatment probabilities between the two groups is one. Suppose the study sponsor has two possible choices regarding the null hypothesis, either to reject it or fail to reject it. (The latter choice is colloquially called “accepting the null hypothesis”, but that is a bit of an overstatement, as the absence of evidence for an effect in a sample typically does not rise to the level of being convincing evidence for the absence of an effect in the population.)

With these two choices about the null hypothesis, there are two major types of “incorrect decisions” that can be made: the null hypothesis could be true for the population but the study data led to a decision to reject the null hypothesis, a result conventionally called a “Type-1” error. Or the null hypothesis could be false for the population but the study data led to a decision not to reject the null hypothesis, conventionally called a “Type-2” error. Conversely, there are also two potentially correct decisions. One could fail to reject the null hypothesis when the null hypothesis is true for the population, a so-called “true negative”, or one could reject the null hypothesis when the null hypothesis is not true, a so-called true positive.

The consequences of these four different decision classifications vary from one stakeholder to another, and thus it is unwise to rely solely and simply on commonly used error probabilities when planning studies. The wiser approach is to set the error probabilities so that they properly account for the relative gains and losses to a stakeholder that arise from correct and incorrect decisions, respectively. From long experience assessing the design of clinical trials for probiotics and prebiotics, I recommend that stakeholders in the design phase of studies give thought to the following three statistical considerations.

Pay attention to power

Power is the probability of avoiding a type-2 error—in other words, under the condition that an assumed true effect exists in a study population and that the type-1 error has been controlled at a given value, power is computed of the probability of avoiding the incorrect decision to fail to reject the null hypothesis. Standard practices are to set the type-1 error at 5% and to determine a sample size that achieves 80% power for an assumed alternative hypothesis, one stating that the true effect is of a specific given magnitude, one corresponding to a so-called meaningful effect size. That effect size is typically called a ‘minimum clinically significant difference’ (MCSD) or something similar, because ideally the assumed effect size would be the smallest of the values that would be clinically important, although as a practical matter — because the higher the magnitude of the effect size, the lower the sample size requirements and thus the better the chance of the study being perceived as “affordable” to study sponsors — the MCSDs used to power studies are often larger than some of the values that would also be clinically significant. Nevertheless, let’s consider what it means for the sponsor to accept that the study should be powered at merely the conventional 80% level. Under the assumptions that the true effect in the population is the MCSD and that the study achieves its target sample size, a sponsor of a study that has only 80% power is taking a 1-in-5 chance that the sample results would not be statistically significant (and that the null hypothesis would fail to be rejected).  Such an incorrect decision could have major adverse implications for the sponsor (and for potential beneficiaries of the intervention), particularly given the investments that have been made in the research program and the implications the incorrect decision could have for misinforming future decisions regarding the specific intervention and indeed related interventions.  A 20% risk may not be worth taking.

All other considerations being equal, the risk of a type-2 error could be lowered by increasing the sample size. Under regular asymptotic assumptions that generally apply, increasing the target sample size by about one-third would cut a 20% type-2 error risk in half, to 10%. Increasing the target sample size by two-thirds reduces it all the way to 5%.

Define the true minimum clinically significant effect size applicable to your study

Another important question is where to set the minimum clinically significant effect. Often that effect is based on prior studies without any adjustment—but this can neglect key considerations. Prior effects of an intervention are typically biased in a direction that overstates the benefits of the intervention, especially if the intervention emerged from smallish early-phase studies. More fundamentally, from the perspective of decision theory the estimated effects seen in prior studies do not specifically address what could truly be the minimum clinically meaningful effect when one considers the possible benefits, risks, and costs of the intervention. Probiotics and prebiotics are typically relatively benign interventions in terms of adverse events, so it could be that even more modest favorable impacts on health than were seen in prior studies are still worthwhile.

Powering your study based on what truly is a minimal clinically meaningful effect may lead to a better overall strategy for optimizing net gains, while giving the intervention an appropriately high chance of showing that it works. Although the smaller the assumed effect size, the larger the required sample size needed to detect it (all other factors being the same), a proper assessment of the relative risks and benefits of the intervention and, also, of correct and incorrect decisions about the intervention, may provide a strong basis for making that investment.

In addition, there is another important but often overlooked aspect when deciding on what is a worthwhile improvement. We frequently turn to clinicians to determine what would be a worthwhile improvement, and it is natural for a clinician to address that question by considering what would be a meaningful improvement for a patient who responds to the intervention. Keep in mind, though, that an intervention could be worthwhile for a population if it achieves what would be a worthwhile improvement for a single patient–say, a mean improvement of 0.2 SD on a quality-of-life scale—in only a fraction of the patients in the overall population, say 50%. There are many conditions for which having an intervention that works for only large subsets of the population could be valuable in improving the population’s overall health and wellness. Using this example, where the worthwhile improvement for an individual is 0.2 SD and the worthwhile responder percentage is 50%, then the worthwhile improvement that should be used to power the study would be 0.1 SD, which is equal to (0.2 SD * 50%) + (0 SD * 50%), with the latter product quantifying an assumed absence of a benefit in the non-responders. What should be gleaned from this example is that the minimum clinically important effect for a population is typically less than the minimum clinically important effect for an individual. The effect used to power the study should be the one that applies to the relevant population. Again, that effect should be chosen so that it balances benefits relative to the costs and harms of the intervention while accounting also for variation in whether and how much individuals in the population may respond. When study planners fail to account for this variation, the result is a study that is underpowered for detecting meaningful population-level effects.

Improving the signal-to-noise ratio

In general, effect sizes can be expressed analogously to a mean difference divided by a standard error, and thus can be thought of as a signal-to-noise ratio. Sample size requirements depend crucially on this signal-to-noise ratio. Typically, standard errors are proportional to outcome standard deviations and inversely proportional to the square root of the sample size. The latter is key because it means that in case an expected signal would be cut in half, the noise would also need to be cut in half to maintain the signal-to-noise ratio, which means that if you cannot alter the outcome standard deviation, then you would need to quadruple the sample size. This also applies in the opposite direction, happily: if you can double the expected signal-to-noise ratio, you would only need one-fourth the sample size to achieve the desired power, all other things being equal.

Signal-to-noise ratios can be optimized by designing a trial for a judiciously restricted target population (of potential responders) and by using high-quality outcome measurements for the trial to reduce noise. Although research programs may eventually aim to culminate in large pragmatic trials that show meaningful improvements associated with an intervention even in populations of individuals with wide variations in their likelihood and amount of potential response, it is generally wise up to that stage in a research program to focus trials so that they give accurate information as to whether the intervention works in populations targeted for being more apt to be responsive to an intervention. To do that, for example, the trial methods should include accurate assessments for whether potential recruits are currently experiencing, say, symptoms from whatever condition the intervention is intended to address and whether the recruit would be able to achieve the desired dose of whatever the trial assigns to them. For a truly beneficial intervention, it is easier to continue a research program advancing the development of that intervention if the intervention sustains a consecutive string of “true positive” results from when it began to undergo trials, avoiding a potentially fatal type-2 error (“false negative”).

Careful attention to the above considerations can lead to better trials, ones that combine rigor and transparency with a tailored consideration of the relative costs and benefits of potentially fallible statistical inferences, so that the resulting evidence is as informative as possible for stakeholder decision-making.

Why responders and non-responders may not be the holy grail for biotics

/in ISAPP Science Blog /by KC

By Prof. Dan Merenstein MD, Georgetown University Medical Center, USA

In September the New York Times published an article titled “What Obesity Drugs and Antidepressants Have in Common“. It was written by a physician who had personally struggled with weight issues and depression. In his personal journey with these health challenges, he hesitates to undergo any treatments. But he eventually does and experiences much relief from them. Why would a practicing physician hesitate to use approved drugs?

The article opens with this viewpoint: “We like to think we understand the drugs we take, especially after rigorous trials have proved their efficacy and safety. But sometimes, we know only that medications work; we just don’t know why.” He goes on to discuss selective serotonin reuptake inhibitors (SSRIs) and  the recently approved weight loss drugs, such as glucagon-like peptide-1 (GLP-1) receptor agonists. The former have been widely used for over 40 years, while the weight loss drugs are more recent. For both classes of drugs, we have some ideas how they work but the exact mechanisms have not been elucidated. While this knowledge gap has not prevented wide usage, the author of the article was skeptical about using the drugs if he did not know exactly how they worked. 

When I started studying probiotics 15 years ago, I began to interact with a different group of scientists than I was used to. My new collaborators were basic and applied scientists, not just clinicians. I had opportunities to attend conferences that covered bench science more than clinical evidence.  My perspective as a clinical researcher was different from most of the others in attendance. I was somewhat surprised to learn how much emphasis those scientists placed on understanding mechanisms. On the one hand, intuitively it makes sense. If you know how something functions, you have a lot more confidence that it will do what you expect it to do, and more assured that it can be used safely. You also have a sense that it should work for you. But on the other hand, knowing an intervention is effective is more important than knowing how it achieves its effectiveness.

This emphasis on understanding mechanisms of action for interventions reminds me of the development of beta-blockers, a class of medicines that block epinephrine, and cause the heart to beat slower and with less force. One of the most common test questions I was asked when I was a medical student and resident is: What class of blood pressure medicines are never permissible for a patient with congestive heart failure (CHF)? Well it was obvious to all of us that the answer was clearly beta-blockers, as you wouldn’t want to slow the heart rate and reduce the force of the heart in a patient already suffering from a poorly performing heart. Yet after clinical trials were completed, beta-blockers were shown to be effective treatment for CHF patients and are now a mainstay of CHF treatment. This was counterintuitive considering the drug’s mechanism of action. So in fact, a drug’s mechanism of action does not always lead in a straightforward way to knowledge about which conditions can be treated or which individuals will respond.

Beyond mechanisms of action and individual response

In clinical medicine, we use two important statistics to capture efficacy and safety of an intervention: number needed to treat (NNT) and number needed to harm (NNH). NNT is the number of patients that need to be treated in order to have an impact on one person, while the NNH is the number of patients who must be treated with an intervention before one patient is harmed.  All interventions have both an NNT and NNH. Obviously, the goal is  a very low NNT and a high NNH. But we are rarely so fortunate. Take for example statins, a medicine many of us take. In patients at low risk of cardiovascular disease, the NNT is 217, which means 1 person out of 217 avoided a nonfatal heart attack by taking statins. Meanwhile, NNH for muscle pain is 21 and for developing diabetes is 204.

NNT and NNH are rarely considered in the biotics field. Yet I commonly encounter discussions about the importance of identifying responders versus non responders to biotic intervention and the need to elucidate the mechanism(s) of action for biotic substances. I believe this is because many of the scientists doing research in biotics come not from a clinical background but more bench research, where the questions really are those of mechanism. Many seem to believe that such knowledge is the Holy Grail of biotics – if only scientists could have such a good grasp of mechanism that they could figure out why certain people responded while others do not. There is nothing inherently wrong with wanting to identify reasons for differences in individual response. It is what we do in clinical practice every day. When I give someone blood pressure medicine and they don’t respond to it, I wonder – Is it a compliance issue? Is the patient’s blood pressure caused by something that the medicine does not impact? Is the patient taking the medication at the wrong time, with the wrong diet, or with other interfering medicines?  Clinicians always must think about who is responding and who is not responding. However, NNT and NNH for biotics are worth prioritizing.

Data have shown that certain probiotics can get people better from an upper respiratory tract infection 26 hours earlier, or can treat infantile colic, or improve irritable bowel syndrome symptoms with a NNT respectively of 20, 15 and 100, while having a very high NNH. These are great products. But instead what I often hear at conferences is that we need to figure out why some people respond to the probiotics and others do not. I agree, go ahead and figure it out. But have realistic expectations. If two of the most widely used medicines, SSRIs and GLP-1 agonists, have an unclear mechanism, and if statins have an NNT of 217, be realistic about the impact of your probiotic. When a doc prescribes you Lipitor, he doesn’t say, “Good luck –  I hope you are the 0.4% in which it helps and aren’t the 5% that gets muscle cramps.” The hope is that for you, the NNT is 1. And when your strain or product does have an impact, feel free to find ways to improve efficacy but celebrate the impact it has. If possible, maybe compare your NNTs to standard of care, or if no comparison look at your NNT versus NNH to really better understand what your biotic can do.

Probiotic Administration in Preterm Infants: Scientific Statement

/in ISAPP Science Blog /by KC

Board of Directors, International Scientific Association for Probiotics and Prebiotics

in collaboration with

Dr. Geoffrey Preidis MD PhD, Pediatric Gastroenterology, Hepatology & Nutrition

Prof. Andi L Shane MD MPH MSc, Pediatric Infectious Diseases

A recent report of a fatality in an extremely premature infant recipient of a probiotic product has resulted in a warning letter from the United States Food & Drug Administration (FDA) to healthcare practitioners about probiotic supplementation in preterm infants and a warning letter to the probiotic product manufacturer.

Publicly available information suggests that this fatality was the direct consequence of bacteremia resulting from ingestion of the probiotic organism Bifidobacterium longum subsp. infantis delivered in medium chain triglyceride oil. This situation differs from case reports of adverse events that resulted from extrinsic probiotic product contamination (1, 2). This is an important distinction, as the potential risks and mitigation strategies differ between etiologies. As complete details of this most recent fatality have not been released, specific factors that may have contributed to the adverse outcome are unknown. However, it is worth considering the context of this case report within the broader literature available on probiotic use in this population, including the wealth of data available on sepsis incidence.

Evidence from systematic reviews

Premature infants, especially those of <32 weeks gestation and with a birth weight <1500 g, are a vulnerable population at significant risk of morbidity and mortality.  Necrotizing enterocolitis (NEC) is highly prevalent (5-10% incidence) among very preterm infants, with mortality rates of 20-30% and high morbidity among survivors, including short gut syndrome, parenteral nutrition-associated liver disease, and neurocognitive delay.

A large body of literature exists on the use of probiotics in hospitalized preterm infants, with particular focus on the prevention of NEC. At least 85 randomised clinical trials (RCTs) (3) have been conducted to evaluate the use of probiotics in preterm infants for the prevention of diseases associated with prematurity, and a number of systematic reviews with meta-analyses have analysed these data in recent years. Most RCTs conducted in the neonatal intensive care unit (NICU) designate sepsis as one of the main outcome measures.

The most recent meta-analysis was published online October 2 in JAMA Pediatrics (3). This study included 106 trials on probiotic, prebiotic, synbiotic and lactoferrin interventions for either preterm infants <37 weeks and/or those with low birth weight (<2500 g). Administration of probiotics containing multiple strains were found to be most effective in the reduction of all-cause mortality (31% reduction), with a 62% decrease in incidence of severe NEC compared to placebo (moderate and high certainty evidence). Single strain probiotics combined with lactoferrin provided greatest efficacy in the reduction of late-onset sepsis incidence (67% risk reduction with moderate certainty evidence). It was noted that none of the included studies reported cases of probiotic-induced sepsis.

Other authors including groups from the Cochrane Collaboration, American Gastroenterological Association (AGA) and the European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) have found similar results, and studies can be reviewed here:

Probiotics to prevent necrotising enterocolitis in very preterm or very low birth weight infants – Sharif, S – 2023 | Cochrane Library

Probiotics Reduce Mortality and Morbidity in Preterm, Low-Birth-Weight Infants: A Systematic Review and Network Meta-analysis of Randomized Trials – Gastroenterology (gastrojournal.org)

Probiotics for Preterm Infants: A Strain-Specific Systematic… : Journal of Pediatric Gastroenterology and Nutrition (lww.com)

No meta-analysis has attributed increased risk of sepsis to probiotic use in preterm infants – rather, in many cases a protective effect (or a trend toward protection) was reported. However, it is important to acknowledge the real but rare risk of probiotic-induced bacteremia in this population. In a recent review of case reports of probiotic-associated invasive infections in children, probiotic-induced bacteremia in premature infants were found to have resolved in most cases with use of effective antimicrobial therapy (4).

With data collected on over 10,000 preterm infants, substantial benefits demonstrated and a low level of risk identified, promise to improve outcomes in preterm infants who receive a probiotic product currently exists. Based on the evidence currently available, hospitals and NICUs across the globe have already adopted practices relating to probiotic use in preterm infants, some with significant health impacts (5, 6).

Risk benefit analysis and considerations for healthcare implementation

Further work needs to be done to support probiotic administration in the NICU. Collaborative efforts include recommendations for practical steps to improve probiotic product quality assurance specifically for NICU use, published in July 2023 in JAMA Pediatrics (7).

It is important to note that few (or possibly no) effective interventions are without an adverse event profile, and probiotics are no exception. Even food has a safety standard of reasonable certainty and on a regular basis, individuals suffer fatal foodborne infections. When considering the clinical indications for any intervention for an individual patient or a population of individuals, a thorough comparison of all available data on both the potential risks and the potential benefits is warranted.

The American Gastroenterological Association (8) and other major societies (including ESPGHAN and the World Gastroenterology Organisation) (9, 10) endorse probiotic products for the prevention of NEC among preterm low birth weight infants. The societies’ guidelines agree that the recommendation to use probiotics is conditional. Conditional recommendations are sensitive to patients’ values and preferences, and to the guideline panel’s perception of risk-benefit balance.  However, the recent FDA letter does not acknowledge these recommendations and further, recommends against probiotic use in preterm infants despite the robust efficacy data. With interventions such as probiotic administration, ideally shared clinical decision-making with patient and clinician would ensue. Regulatory warnings inform the risk-benefit calculation but typically do not invalidate a clinical recommendation.

Summary

  • Probiotic administration to preterm infants has been demonstrated to significantly reduce the risk of NEC, sepsis and death in large systematic reviews with meta-analyses.
  • Meta-analyses have not identified significant adverse events or safety concerns, although rare case reports have documented sepsis attributed to probiotics.
  • Stringent manufacturing standards are recommended for probiotics in vulnerable populations such as preterm infants.
  • Standardized comprehensive safety reporting across probiotic intervention studies is needed, along with funding for the conduct of long term studies.
  • The risks and benefits of probiotic administration should be considered in both the specific population and individual patients, with regulatory frameworks to enable implementation.
  • More information about this fatality should be immediately released so healthcare professionals and researchers can learn from this experience and continue to provide optimal evidence-based patient care.

To inquire about expert academic physicians available for media comment, please contact ISAPP’s Executive Director, Marla Cunningham, at marla@nullisappscience.org

See also:

NEC Society: Statement on FDA Warning of Probiotics in Preterm Infants

References

(1) Vallabhaneni S, Walker TA, Lockhart SR, et al. Notes from the field: Fatal gastrointestinal mucormycosis in a premature infant associated with a contaminated dietary supplement–Connecticut, 2014. MMWR Morb Mortal Wkly Rep. 2015;64(6):155-156.

(2) Bizzarro MJ, Peaper DR, Morotti RA, Paci G, Rychalsky M, Boyce JM. Gastrointestinal Zygomycosis in a Preterm Neonate Associated With Contaminated Probiotics. Pediatr Infect Dis J. 2021;40(4):365-367.

(3) Wang Y, Florez ID, Morgan RL, et al. Probiotics, Prebiotics, Lactoferrin, and Combination Products for Prevention of Mortality and Morbidity in Preterm Infants: A Systematic Review and Network Meta-Analysis. JAMA Pediatr. 2023 Oct 2:e233849.

(4) D’Agostin M, Squillaci D, Lazzerini M, et al. Invasive Infections Associated with the Use of Probiotics in Children: A Systematic Review. Children (Basel). 2021 Oct 16;8(10):924.

(5)  Rath CP, Athalye-Jape G, Nathan E, et al. Benefits of routine probiotic supplementation in preterm infants. Acta Paediatr. 2023 Jul 28.

(6) Bui A, Johnson E, Epshteyn M, Schumann C, Schwendeman C. Utilization of a High Potency Probiotic Product for Prevention of Necrotizing Enterocolitis in Preterm Infants at a Level IV NICU. The Journal of Pediatric Pharmacology and Therapeutics 2023;28(5):473–475.

(7)  Shane AL, Preidis GA. Probiotics in the Neonatal Intensive Care Unit-A Framework for Optimizing Product Standards. JAMA Pediatr. 2023 Sep 1;177(9):879-880.

(8) Su GL, Ko CW, Bercik P, et al. AGA Clinical Practice Guidelines on the Role of Probiotics in the Management of Gastrointestinal Disorders. Gastroenterology. 2020 Aug;159(2):697-705.

(9) WGO Practice Guideline: Probiotics and Prebiotics. Available from: https://www.worldgastroenterology.org/guidelines/probiotics-and-prebiotics

(10) van den Akker CHP, van Goudoever JB, Shamir R, et al. Probiotics and Preterm Infants: A Position Paper by the European Society for Paediatric Gastroenterology Hepatology and Nutrition Committee on Nutrition and the European Society for Paediatric Gastroenterology Hepatology and Nutrition Working Group for Probiotics and Prebiotics. J Pediatr Gastroenterol Nutr. 2020 May;70(5):664-680.

New global guidelines for probiotics and prebiotics for gut health and disease

/in ISAPP Science Blog /by KC

By Mary Ellen Sanders, PhD, Executive Science Officer, ISAPP

The use of probiotics and prebiotics in the practice of gastroenterology must be guided by evidence – and with new evidence continually emerging, clinicians can benefit from efforts to summarize this evidence and determine how it applies in clinical practice.

In February 2023, the World Gastroenterology Organisation provided an updated resource in this area, titled “WGO Practice Guideline. Probiotics and Prebiotics”. This project was led by Prof. Francisco Guarner MD PhD, a clinical gastroenterologist and clinical researcher in probiotics and prebiotics, and brought together experts in gastroenterology, pediatrics, family medicine, probiotics, and prebiotics. Prof. Hania Szajewska MD PhD, a clinical pediatrician and clinical researcher in probiotics from the Medical University of Warsaw, was integral to assessing evidence for pediatric populations for the guidelines. Mary Ellen Sanders PhD co-chaired the project.

For 2023 update, 800 bibliographical entries of papers published in the 2017-2021 period were scrutinized. The review team adopted the guidelines for evaluation of probiotics established by FAO/WHO experts in 2002, where at least one double blind, randomized, placebo-controlled human trial with appropriate sample size and primary outcome is required to determine if the tested product is efficacious, and qualifies as a probiotic.

ISAPP was well-represented among the experts involved on the project, as four current board members contributed. In addition to Sanders and Szajewska, Prof. Dan Merenstein MD (current ISAPP president) and Prof. Seppo Salminen PhD (current past president) populated the team.

The Guideline is intended to provide specific information on interventions that may have benefit for indicated conditions. Recommendations included probiotics or prebiotics found in at least one randomized, controlled trial showing benefit. Trials that did not show benefit were not included. The Guideline serves an important role in informing gastroenterologists around the world, especially in regions where product availability might be limited. Especially useful are Tables 8 and 9, which summarize evidence for adult and pediatric uses, respectively.

Guarner states, “We hope our WGO guideline will assist doctors, pharmacists, dietitians and other healthcare professionals all around the world to integrate probiotics and prebiotics in an evidence-based manner into their daily work of patient care.”

The Guideline provides text that introduces current understanding of probiotics and prebiotics and then comprehensively evaluates the evidence for gastrointestinal conditions. Evidence is graded from 1-3, with Level 1 referring to evidence supported by systematic review of randomized trials, Level 2 supported by randomized trials with consistent effect, without systematic review, and Level 3, supported by a single randomized controlled trial, as per the Oxford Centre for Evidence-Based Medicine.

The 2017 iteration of these guidelines was available in six languages (English, French, Portuguese, Mandarin, Russian and Spanish). This guideline is the most accessed guideline title on the WGO website,  accounting for nearly one-quarter of all visits to the site. The 2023 version is only available in English so far, but translations are underway.

Clinical conditions for which some evidence was found include:

  • Diarrheal conditions: acute, antibiotic-associated, difficile-associated, radiotherapy-associated, enteral nutrition-associated, nosocomial,
  • Diverticular disease
  • Functional abdominal pain
  • Functional constipation
  • Insulin resistance
  • Health-related quality of life
  • Helicobacter pylori infection
  • Hepatic encephalopathy
  • Infantile colic
  • Inflammatory bowel disease
  • Irritable bowel syndrome
  • Lactose maldigestion
  • Nonalcoholic fatty liver disease
  • Nonalcoholic steatohepatitis
  • Necrotizing enterocolitis

 

About WGO:
World Gastroenterology Organisation (WGO) is a federation of over 100 Member Societies and four Regional Associations of gastroenterology representing over 60,000 individual members worldwide.  The WGO Guidelines Library contains practice guidelines written from a viewpoint of global applicability. The Guidelines go through a rigorous process of authoring, editing, and peer review and are as evidence based as possible.

Pasteurized Akkermansia muciniphila as a postbiotic: EFSA approval and beyond

/in ISAPP Science Blog /by KC

By Prof. Seppo Salminen, University of Turku, Finland

Earlier this year, the European Food Safety Authority (EFSA) delivered an opinion that heat-treated Akkermansia muciniphila is safe for use as a novel food in the European Union. EFSA described A. muciniphila as a “well‐characterised non‐toxin producing, avirulent microorganism that has been reported as part of normal gut microbiota” and determined based on a literature review that its safety is adequate for use as a food supplement or in foods for special medical purposes, at a specified maximum dose.

ISAPP connected with three individuals from A-Mansia Biotech, the company that initiated the EFSA request: Prof. Willem M. de Vos and Prof. Patrice D. Cani, as well as the company CEO Michael Oredsson. They jointly answered some questions on their EFSA success and plans for the future.

Originally, what led you to test whether the pasteurized form of the live microbe might be able to confer a health benefit?

We first noticed that killing Akkermansia by using autoclaving (121°C 20°C) completely abolished the beneficial effects of Akkermansia. However, we wanted to test whether a milder procedure (i.e. pasteurization) could keep some structures of the outer membrane of Akkermansia intact and therefore still able to interact with the host. We knew that several other classical probiotics (types of lactobacilli) partly retained their effects after pasteurization. Our surprise was to see that pasteurization successfully maintained the effects of Akkermansia compared to the live form, but even increased its efficacy.

Pasteurised Akkermansia has now been extensively studied for safety and health effects. Does this make it the first real postbiotic, as defined by ISAPP?

If we are accepting the ISAPP definition proposed in 2021, we can answer yes to this question. Prof. Cani in his scientific capacity believes indeed that the product (pasteurized Akkermansia) is unique and can fall under this definition. Whether A-Mansia will be positioning the pasteurized Akkermansia as a postbiotic according to that definition is still to be discussed.

Pasteurised Akkermansia has been demonstrated to control gut barrier and reduce inflammation associated with fat storage and obesity – will we see a product that helps in weight loss/control?

Akkermansia is clearly playing a major role by tackling the gut barrier dysfunction which is the root cause of the different metabolic problems mentioned here (i.e., inflammation, fat storage, liver/fat tissue inflammation) and they are all connected to better energy expenditure/oxidation when a lower inflammation/insulin resistance is observed. Therefore, pasteurized Akkermansia should help to maintain a healthy weight and abdominal fat. A product focusing on a better weight management is currently under development at A-Mansia.

Is the next step to apply for an EU health claim?

All the current human investigations and studies at our company are aiming at fulfilling future EU health claims.

It took two years to get the acceptance for the safety of inanimate pasteurised Akkermansia – what do you think of this timeframe for safety assessment?

This is perfectly in line with what the EFSA was expecting, although it was a few months delayed with the COVID-19 crisis. The assessment was very clear, smooth and well managed by the EFSA.

In general, what do you think the future holds for postbiotics as food ingredients?

We are entering into a new era, first with next-generation beneficial bacteria, and Akkermansia as one of the most studied (if not the most studied). The pasteurized form is so active, stable, and easy to use that the postbiotic era, as led by this example, is a novel and innovative manner of targeting the microbiome for improving/maintaining health.

 

As the science on health benefits for similar postbiotic substances continues to advance, we may see more ingredients qualifying as true postbiotics. More products are likely to follow a similar path, considering the practical advantages of delivering non-living substances to consumers.

 

Can dietary supplements be used safely and reliably in vulnerable populations?

/in ISAPP Science Blog /by KC

By Dr. Greg Leyer, Sr. Director – Scientific Affairs, Chr. Hansen, Inc., Madison, WI and Prof. Dan Merenstein, Department of Family Medicine, Georgetown University Medical Center, Washington DC

What is it that doctors look for when recommending or prescribing therapies to patients? If it is a drug, a supplement, a new diet, or even a new exercise regimen, they look for safety and efficacy. There are of course other things to consider, including cost, ease of administration, and patient compliance, among others. But safety and efficacy are their foremost concerns.

A recently published clinical report from the American Academy of Pediatrics (AAP) (Poindexter 2021) examined the evidence for probiotics to prevent morbidity and mortality in preterm infants. They concluded that probiotics could not be recommended. This differs from conclusions of the American Gastroenterological Association (AGA) (Su et al. 2020), which recommended specific probiotic strains for preterm (less than 37 weeks gestational age) and low birth weight infants. The AAP report also differs from the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) (Van den Akker et al. 2020), which recommends specific strains for this use, although their recommendations are not fully aligned with AGA’s (see What’s a Clinician to do When the Probiotic Recommendations from Medical Organizations Do Not Agree?).

The AAP report does a thorough job of reviewing data on use of probiotics in the NICU, including conflicting studies, lack of confirmatory studies of efficacious strains, and safety and cross contamination inside the NICU. However, the overriding theme of the report is “clinicians must be aware of the lack of regulatory standards for commercially available probiotic preparations manufactured as dietary supplements and the potential for contamination with pathogenic species.” Therefore, at the heart of the AAP failure to recommend probiotics is the concern that the quality of available products is insufficient. Because of the absence of a pharmaceutical-grade probiotic product for use in the United States, they posit, they cannot recommend usage. It is noteworthy that the trials performed on premature infants resulting in multiple conclusions of safety and efficacy have thus far utilized probiotic products manufactured as dietary supplements.

Probiotics can be marketed as drugs if they follow that regulatory pathway, but generally in the US they are sold under the regulatory classification of dietary supplements. Is the AAP correct that no dietary supplement is of sufficient quality to recommend for use in preterm infants?

Quality of probiotic dietary supplement probiotics. Dietary supplements were a category of product developed to supplement the diet of the generally healthy population, not to treat or prevent disease. In practice this is an important distinction, because while the safety standard is high for dietary supplements for healthy individuals (see comments by food safety expert Jim Heimbach here), such supplements do not need to be established as safe for patient populations. But in the case of probiotics, many clinical trials have evaluated safety and efficacy for prevention or treatment of disease, more aligned with drug uses. Yet probiotic products supported by these data are not marketed in the US as drugs.

It is a common misperception that dietary supplements are “not regulated”. However, the FDA has clear good manufacturing practices (GMP’s) and regulations dedicated to dietary supplement manufacturing.  The onus is on manufacturers to establish appropriate product specifications based on intended use and risk. Reputable manufactures establish rigorous purity, strength, and identity quality standards consistent with the intended population and sufficient for that use. Products intended for infants, including premature infants, should be manufactured under quality standards more rigorous than those intended for a healthy adult population. For example, Chr. Hansen bases the enhanced specifications for products aimed at infants, and preterm infants, on elements of Codex standards for infant formula, amongst other stringent microbiological criteria. This would include manufacturing the probiotic strain to an “infant” grade, employing stricter environmental monitoring, sanitation, and airflow control throughout the process, careful selection of raw ingredients for infant compatibility, and enhanced testing and purity standards using validated methods at every step. The internal manufacturing standards that Chr. Hansen applies for products intended for infants, and preterm infants, are much stricter than typical dietary supplement standards, and are appropriate for their intended use.

Therefore, there are high quality, safe probiotic products produced under dietary supplement regulations even though such products do not carry any label statement claiming this added level of quality. However, products sourced for hospitals to stock in formularies could work with the supplier to demand this extra level of product testing specifications. Pharmacies can institute quality agreements with vendors that would delineate their expectations for the strains present, the levels of live microbes acceptable in the final product, etc. This agreement could also mandate that any product change – as defined in the agreement – would require the vendor to notify the customer. Such an agreement might be burdensome for a hospital pharmacist, but a sophisticated dietary supplement company should be able to assure the hospital formulary of their quality.

Products made using strict specifications, geared towards infant and premature infant applications, are on the market and are safely being used in this patient population in many NICUs and as part of infant formulas. We disagree with AAP’s position that a pharmaceutical approach is needed, as long as a product of sufficient quality can be provided. To deny preterm infants probiotics, which have a significant chance of improving their clinical outcomes, is not in line with other medical recommendations. Instead, the hospital formularies should stock products that have been scrutinized for sufficient evidence of safety and efficacy. Suppliers of stocked products should provide product testing results, a description of the quality standards employed during production, and a rationale for the suitability of the standards for preterm infants. Third party verification of adherence to these quality standards would assure medical professionals regarding the safety of these products for use.

References

CAC/RCP 66-2008. Code of hygienic practice for powdered formulae for infants and young children. Codex.

Poindexter, B. 2021. Use of Probiotics in Preterm Infants. Pediatrics 147 (6): e202 1051485.

Su et al. 2020. AGA Clinical Practice Guidelines on the Role of Probiotics in the Management of Gastrointestinal Disorders. Gastroenterology 159:697-705.

Van den Akker et al.  2020. Probiotics and Preterm Infants: A Position Paper by the European Society for Paediatric Gastroenterology Hepatology and Nutrition Committee on Nutrition and the European Society for Paediatric Gastroenterology Hepatology and Nutrition Working Group for Probiotics and Prebiotics. Journal of Pediatric Gastroenterology and Nutrition. 70(5):664-680.

 

 

A postbiotic is not simply a dead probiotic

/in ISAPP Science Blog /by KC

By Dr. Gabriel Vinderola, PhD,  Associate Professor of Microbiology at the Faculty of Chemical Engineering from the National University of Litoral and Principal Researcher from CONICET at Dairy Products Institute (CONICET-UNL), Santa Fe, Argentina

Postbiotics, recently addressed in an ISAPP consensus panel paper, are defined as a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host. Criteria to meet the postbiotic definition are summarized here. One noteworthy aspect of this definition is that the word ‘probiotic’ does not appear. Although in practice a probiotic strain may be used as a progenitor strain in the manufacture of a postbiotic, the simple process of inactivating a probiotic is not sufficient to be called a postbiotic. It cannot be assumed that any non-viable probiotic cells in a probiotic product are automatically considered a postbiotic component. If a probiotic strain is used as a progenitor of a postbiotic, an efficacy study must be redone using the inanimate preparation and a benefit must be demonstrated. A probiotic product displaying fewer than the labeled count of viable cells is merely a low-quality product; it is not a postbiotic.

Further, the ISAPP consensus definition on postbiotics recognizes that the process of making a postbiotic implies a deliberate step to inactivate the viable cells of the progenitor strain. This process can be achieved by different technological steps such as heat-treatment (perhaps the most feasible approach), high pressure, radiation or simply aerobic exposure for strict anaerobes. A corresponding efficacy study must be conducted on the preparation. Or at the very least, any postbiotic component of a probiotic product must be specifically shown to contribute to the health benefit conferred by the product.

In contrast to postbiotics, probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. Four minimum criteria should be met for a strain to be considered as a probiotic: (i) sufficiently characterized; (ii) safe for the intended use; (iii) supported by at least one positive human clinical trial conducted according to generally accepted scientific standards or as per recommendations and provisions of local/national authorities when applicable; and (iv) alive in the product at an efficacious dose throughout shelf life (Binda et al. 2020). This last requirement reflects the key difference between probiotics and postbiotics. Probiotics must deliver an efficacious number of viable cells through the shelf life of the product. In practice, probiotic products may display significant numbers of non-viable cells (Raymond & Champagne, 2015), as some cells may lose viability during the technological process of biomass production, while undergoing manufacture or preservation steps and through product storage prior to purchase. In order to provide the target dose until end of shelf life, an overage of 0.5 to 1 log order CFU above the expected counts of viable cells is commonly included in the product to compensate for potential losses during product storage and handling (Fenster et al. 2019).

Thus, some quantity of non-viable cells may be usually expected in certain probiotic products, especially supplement products claiming a long, room temperature stable shelf-life. However, they will be considered as probiotic products of quality as long as they are able to deliver the expected amount of viable cells until the end of the product shelf-life. It is worth mentioning that the probiotics are expected to be viable at the moment of their administration. After that, if exposure to different regions of the gut causes cells to die, it is not of consequence as long as a health effect is achieved.

Probiotics and postbiotics have things in common (the need of efficacy studies that demonstrates their benefits) and things that distinguish them (the former are administered alive, whereas the latter are administrated in their inanimate form), but no probiotic becomes a postbiotic just by losing cell viability during storage.

What’s the evidence on ‘biotics’ for health? A summary from five ISAPP board members

/in Consumer Blog, ISAPP Science Blog /by KC

Evidence on the health benefits of gut-targeted ‘biotics’ – probiotics, prebiotics, synbiotics, and postbiotics – has greatly increased over the past two decades, but it can be difficult to sort through the thousands of studies that exist today to learn which of these ingredients are appropriate in which situations. At a recent World of Microbiome virtual conference, ISAPP board members participated in a panel that provided an overview of what we currently know about the health benefits of ‘biotics’ and how they are best used.

Here’s a summary of what the board members had to say:

Dr. Mary Ellen Sanders: Probiotics and fermented foods

  • Probiotics are “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”.
  • Unfortunately, published assessments of probiotic products available on the market show that these products often fall short of required evidence. For example, their labels may not adequately describe the contents (including genus / species / strain in the product); they may not guarantee the efficacious dose through the end of the shelf life.
  • Contrary to common belief, probiotics do not need to colonize in the target site (e.g. the gut), impact gut microbiota composition, be derived from humans, or be resistant to stomach acid and other gut secretions such as bile.
  • Fermented foods are those made “through desired microbial growth and enzymatic conversions of food components”. The recent increased interest in fermented foods may come from people’s increased awareness of the role of gut microbes in overall health, but it is important to note that we have little direct evidence that the transient effects of fermented food microbes on the gut microbiota actually lead to health benefits. With that said, observational studies suggest that consuming some traditional fermented foods is associated with improved health outcomes.

Prof. Dan Merenstein, MD: Probiotics – How do I know what to prescribe for adult health?

  • A (limited) survey showed that most dietary supplement probiotic products cannot be linked to evidence because they do not provide enough information to determine what evidence exists to support their use – especially strains in the product. However, there are some probiotic products that have robust evidence.
  • Should every adult take a probiotic? The best evidence supports probiotics for improved lactose digestion and for prevention of difficile infection. Probiotics have also been shown to prevent common illnesses; reduce the duration of gut symptoms; and perhaps even reduce antibiotic consumption.
  • Studies will reveal more about the microbiome and about how probiotics work, for whom and for what indications. As with diet, the answer will most likely not be same for each person.

Prof. Glenn Gibson: Prebiotics and Synbiotics

  • A prebiotic is “a substrate that is selectively utilized by host microorganisms conferring a health benefit”. Researchers can test these substances’ activity in various ways: batch cultures, micro batch cultures, metabolite analysis, molecular microbiology methods, CF gut models, with in vivo (e.g. human) studies being required. Prebiotics appear to have particular utility in elderly populations, and may be helpful in repressing infections, inflammation and allergies. They have also been researched in clinical states such as IBS, IBD, autism and obesity related issues (Gibson et al., 2017).
  • A synbiotic is “a mixture, comprising live microorganisms and substrate(s) selectively utilized by host microorganisms, that confers a health benefit on the host.” While more studies are needed to say precisely which are useful in which situations, synbiotics have shown promise for several aspects of health in adults (Swanson et al. 2020): surgical infections and complications, metabolic disorders (including T2DM and glycaemia), irritable bowel syndrome, Helicobacter pylori infection and atopic dermatitis.

Prof. Hania Szajewska, MD: Biotics for pediatric use

  • Beneficial effects of ‘biotics’ are possible in pediatrics, but each ‘biotic’ needs to be evaluated separately. High-quality research is essential.
  • It is important that we view the use of ‘biotics’ in the context of other things in a child’s life and other interventions.
  • Breast milk is the best option for feeding infants
  • If breastfeeding is not an option, infant formulae supplemented with probiotics and/or prebiotics and/or postbiotics are available on the market.
  • Pro-/pre-/synbiotic supplemented formulae evaluated so far seem safe with some favorable clinical effects possible, but the evidence is not robust enough overall to be able to recommend routine use of these formulae.
  • Evidence is convincing on probiotics for prevention of necrotizing enterocolitis in preterm infants.
  • Medical societies differ in their recommendations for probiotics to treat acute gastroenteritis in children – they appear beneficial but not essential.
  • Synbiotics are less studied, but early evidence indicates they may be useful for preventing sepsis in infants and preventing / treating allergy and atopic dermatitis in children.

Prof. Gabriel Vinderola: Postbiotics

  • The concept of non-viable microbes exerting a health benefit has been around for a while, but different terms were used for these ingredients. Creating a scientific consensus definition will improve communication with health professionals, industry, regulators, and the general public. It will allow clear criteria for what qualifies as a postbiotic, and allow better tracking of scientific papers for future systematic reviews and meta-analyses.
  • The ISAPP consensus definition (in press) of a postbiotic is: “A preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”.
  • Postbiotics are stable, so no cold-chain is needed to deliver them to the consumer. Safety is of less concern because the microbes are not alive and thus cannot cause bacteraemia.
  • Research in the coming years will reveal more about postbiotics and the ways in which they can promote human health.

See here for the entire presentation on Biotics for Health.

Probiotics and fermented foods, by Dr. Mary Ellen Sanders (@1:15)

Postbiotics, by Prof. Gabriel Vinderola (@18:22)

Prebiotics and synbiotics, by Prof. Glenn Gibson (@33:24)

‘Biotics’ for pediatric use, by Prof. Hania Szajewska (@47:55 )

Probiotics: How do I know what to prescribe for adult health? by Prof. Dan Merenstein (@1:04:51)

Q&A (@1:20:00)

 

60 Minutes’ 13 minutes on probiotics

/in ISAPP Science Blog /by KC

By Mary Ellen Sanders, PhD, ISAPP Executive Science Officer 

On June 28, 60 Minutes aired a 13-minute segment about probiotics titled, “Do Probiotics Actually Do Anything?” Unfortunately the media segment did not provide listeners with a nuanced perspective.

‘Probiotics’ were treated as if they were one entity, ignoring the best approach to addressing the topic of what probiotics do: evaluate the evidence for specific strains, doses and endpoints, and then make a conclusion based on the totality of the evidence. They would have found that many experts agree that actionable evidence exists for certain probiotics to prevent antibiotic associated diarrhea (here, here), prevent upper respiratory tract infections (here), prevent morbidity and mortality associated with necrotizing enterocolitis (here,), treat colic (here), and treat acute pediatric gastroenteritis (here). (For an overall view of evidence, see here.)

Importantly, not all retail probiotics have evidence (at least evidence that is readily retrievable, see here and here). But that does not mean that none do.

The 60 Minutes segment also highlighted questions about probiotic safety. No intervention is without risk, and no one claims as much for probiotics. Prof. Dan Merenstein, MD, just one clinical investigator of probiotics, has collected over 20,000 pediatric clinical patient days’ worth of safety data over the past eight years of clinical investigation, with no indication of safety concerns. In fact, participants in the placebo group generally have more adverse events than in the probiotic groups. But importantly, the safety standard for probiotics was mischaracterized by 60 Minutes. According to Dr. James Heimbach, a food safety expert (not interviewed in the segment) who has conducted 41 GRAS determinations on probiotics, over 25 of them notified to the FDA, he objects to the statement that GRAS is a lower safety bar than a drug. He clarifies:

“The safety standard that applies to food additives and GRAS substances, “reasonable certainty of no harm,” is a far higher standard than that applying to drugs. Drugs are judged against a risk/benefit standard, which can potentially allow quite dangerous drugs on the market provided they offer a significant benefit. The safety standard for drugs also applies only to prescribed doses for specific individuals over prescribed durations. The food-additive/GRAS substance standard, on the other hand, requires safety at any biologically plausible level of intake, for any person (child, adult, elderly; pregnant; etc.), over a lifetime. And it is a risk-only standard—no potential benefit is allowed to override the “reasonable certainty of no harm” standard. Additionally, in the case of GRAS substances (which includes most probiotics), the evidence of safety must be published in the peer-reviewed scientific literature and be widely accepted by the scientific community as well as by government regulators.”

Finally, the story implied that benefits people claim for themselves when using probiotics are due to a placebo effect. This ignores the many properly controlled studies directly comparing the effects of specific probiotics to placebos. A positive trial on probiotics, such as observed in this recent trial on irritable bowel syndrome symptoms (here) and in most trials included in Cochrane meta-analyses on prevention of C. difficile-associated diarrhea (here), means that positive effects were observed beyond any placebo effect. The placebo effect is real, equally applicable to probiotics and drugs, but as with all clinically evaluated substances, properly controlled trials control for this effect.

The probiotic field has come a long way over the past 20 years with regard to number and quality of clinical trials. In that time, well-done systematic reviews of the evidence have found benefits for specific probiotics for specific conditions, while also finding a lack of evidence for beneficial effects in other contexts. There are of course well-conducted clinical trials that have failed to demonstrate benefit (here, here, here). This should not be equated to mean that probiotics do not do anything.

Many challenges remain for improving the quality of the evidence across the wide range of different strains, doses, endpoints and populations. More clinical research needs to be conducted in a manner that minimizes bias and is reported according to established standards. Confidence in the quality of commercial products could be improved by industry adopting third party verification (here), and the quality of products targeting compromised populations need to be fit for purpose (here). Companies should stop using the term ‘probiotic’ on products that have no evidence warranting that description. We need to understand much better how a person’s individual situation, such as diet, microbiome, use of medications and fitness, impact the ability of a probiotic to promote health. Much remains to be learned in this evolving and exciting field. As Dr. Merenstein says, “The key question is not, ‘Do probiotics actually do anything?’, as that is easily answered ‘yes’ when you look at robust placebo-controlled trials of specific probiotics. Better questions are ‘Which probiotics do anything, and for what?’”

Further reading:

Misleading press about probiotics: ISAPP responses

ISAPP take-home points from American Gastroenterological Association guidelines on probiotic use for gastrointestinal disorders

New publication gives a rundown on probiotics for primary care physicians

Safety and efficacy of probiotics: Perspectives on JAMA viewpoint

ISAPP provides guidance on use of probiotics and prebiotics in time of COVID-19

/in ISAPP Science Blog, News /by KC

By ISAPP board of directors

Summary: No probiotics or prebiotics have been shown to prevent or treat COVID-19 or inhibit the growth of SARSCoV-2. We recommend placebo-controlled trials be conducted, which have been undertaken by some research groups. If being used in clinical practice in advance of such evidence, we recommend a registry be organized to collect data on interventions and outcomes.  

Many people active in the probiotic and prebiotic fields have been approached regarding their recommendations for using these interventions in an attempt to prevent or treat COVID-19. Here, the ISAPP board of directors provides some basic facts on this topic.

What is known. Some human trials have shown that specific probiotics can reduce the incidence and duration of common upper respiratory tract infections, especially in children (Hao et al. 2015; Luoto et al. 2014), but also with some evidence for adults (King et al. 2014) and nursing home residents (Van Puyenbroeck et al. 2012; Wang et al. 2018). However, not all evidence is of high quality and more trials are needed to confirm these findings, as well as determine the optimal strain(s), dosing regimens, time and duration of intervention. Further, we do not know how relevant these studies are for COVID-19, as the outcomes are for probiotic impact on upper respiratory tract infections, whereas COVID-19 is also a lower respiratory tract infection and inflammatory disease.

There is less information on the use of prebiotics for addressing respiratory issues than there is for probiotics, as they are used mainly to improve gut health. However, there is evidence supporting the use of galactans and fructans in infant formulae to reduce upper respiratory infections (Shahramian et al. 2018; Arslanoglu et al. 2008). A meta-analysis of synbiotics also showed promise in repressing respiratory infections (Chan et al. 2020).

Mechanistic underpinnings. Is there scientific evidence to suggest that probiotics or prebiotics could impact SARS-CoV-2? Data are very limited. Some laboratory studies have suggested that certain probiotics have anti-viral effects including against other forms of coronavirus (Chai et al. 2013). Other studies indicate the potential to interfere with the main host receptor of the SARS-CoV-2 virus, the angiotensin converting enzyme 2 (ACE2). For example, during milk fermentation, some lactobacilli have been shown to release peptides with high affinity for ACE (Li et al. 2019). Recently, Paenibacillus bacteria were shown to naturally produce carboxypeptidases homologous to ACE2 in structure and function (Minato et al. 2020). In mice, intranasal inoculation of Limosilactobacillus reuteri (formerly Lactobacillus reuteri) F275 (ATCC 23272) has been shown to have protective effects against lethal infection from a pneumonia virus of mice (PVM) (Garcia-Crespo et al. 2013). These data point towards immunomodulatory effects involving rapid, transient neutrophil recruitment in association with proinflammatory mediators but not Th1 cytokines. A recent study demonstrated that TLR4 signaling was crucial for the effects of preventive intranasal treatment with probiotic Lacticaseibacillus rhamnosus (formerly Lactobacillus rhamnosus) GG in a neonatal mouse model of influenza infection (Kumova et al., 2019). Whether these or other immunomodulatory effects, following local or oral administration, could be relevant to SARS-CoV-2 infections in humans is at present not known.

Our immune systems have evolved to respond to continual exposure to live microbes. Belkaid and Hand (2016) state: “The microbiota plays a fundamental role on the induction, training, and function of the host immune system. In return, the immune system has largely evolved as a means to maintain the symbiotic relationship of the host with these highly diverse and evolving microbes.” This suggests a mechanism whereby exposure to dietary microbes, including probiotics, could positively impact immune function (Sugimura et al. 2015; Jespersen et al. 2015).

The role of the gut in COVID-19. Many COVID-19 patients present with gastrointestinal symptoms and also suffer from sepsis that may originate in the gut. This could be an important element in the development and outcome of the disease. Though results from studies vary, it is evident that gastrointestinal symptoms, loss of taste, and diarrhea, in particular, can be features of the infection and may occur in the absence of overt respiratory symptoms. There is a suggestion that gastrointestinal symptoms are associated with a more severe disease course. Angiotensin converting enzyme 2 and virus nucleocapsid protein have been detected in gastrointestinal epithelial cells, and infectious virus particles have been isolated from feces. In some patients, viral RNA may be detectable in feces when nasopharyngeal samples are negative. The significance of these findings in terms of disease transmission is unknown but, in theory, do provide an opportunity for microbiome-modulating interventions that may have anti-viral effects (Cheung et al. 2020; Tian et al. 2020; Han et al. 2020).

A preprint (not peer reviewed) has recently been released, titled ‘Gut microbiota may underlie the predisposition of healthy individuals to COVID-19’ (Gao et al. 2020) suggesting that this could be an interesting research direction and worthy of further discussion. A review of China National Health Commission and National Administration of Traditional Chinese Medicine guidelines also suggested probiotic use, although more work on specific strains is needed (Mak et al. 2020).

Are probiotics or prebiotics safe? Currently marketed probiotics and prebiotics are available primarily as foods and food/dietary supplements, not as drugs to treat or prevent disease. Assuming they are manufactured in a manner consistent with applicable regulations, they should be safe for the generally healthy population and can be consumed during this time.

Baud et al. (in press) presented a case for probiotics and prebiotics to be part of the management of COVID-19. Although not fully aligned with ISAPP’s official position, readers may find the points made and references cited of interest.

Conclusion. We reiterate, currently no probiotics or prebiotics have been shown to prevent or treat COVID-19 or inhibit the growth of SARSCoV-2.

 

Safety and efficacy of probiotics: Perspectives on JAMA viewpoint

/in ISAPP Science Blog /by KC

By Mary Ellen Sanders PhD, executive science officer, ISAPP,  and Daniel Merenstein MD, Department of Family Medicine, Georgetown University School of Medicine

The Journal of the American Medical Association (JAMA) recently published a short viewpoint that called into question the safety and efficacy of probiotics. After careful review, we concluded that some opinions expressed were not consistent with available data. We share our perspectives here.

Claim 1: The paucity of high-quality data supporting the value of probiotics.

The authors speak to the “paucity” and “lack” of data supporting probiotic use. They criticize probiotic meta-analyses in general, even though there are many well-done ones, which describe clear PICOS, assess the quality of studies included, and assess publication bias. Many conclude that there is evidence that certain probiotics may be beneficial for several clinical endpoints. In the case of treatment of colic, an individual participant data meta-analysis was conducted on a single strain, and concluded “L reuteri DSM17938 is effective and can be recommended for breastfed infants with colic” (Sung et al. 2018). For necrotizing enterocolitis (NEC), a change in practice is recommended by a Cochrane meta-analysis (AlFaleh et al. 2018), which is consistent with draft American Gastroenterological Association (AGA) recommendations posted last month. In some cases, conclusions are qualified as being based on low quality data, which is also the case with many standard-of-care medical interventions. Other benefits supported for certain probiotics by evidence are shown in Table 1 of Sanders et al. 2018. But an evidence-based review of available data would not support a general statement that “data are lacking.”

Instead, we think a discussion of what evidence is actionable is reasonable to have. For this discussion, different people or groups can reasonably set the bar at different levels for what constitutes actionable evidence. But several medical organizations, including the European Society for Paediatric Gastroenterology, Hepatology and Nutrition, World Gastroenterology Organisation, American College of Gastroenterology, AGA (proposed, for antibiotic-associated diarrhea, NEC and pouchitis), European Crohn’s and Colitis Organization, and European Society for Primary Care Gastroenterology have actionable recommendations for probiotic use for one or more indications. For those indications, any individual physician may judge that the available evidence as not convincing to him or her, but many qualified healthcare experts did find the evidence convincing and have made recommendations accordingly. We recognize that the JAMA viewpoint was limited in the number of words and references allowed, but to impugn an entire field, the authors are obliged to explain why their views differ so much from established organizations.

The authors also criticize the inclusion of small, single-center trials in probiotic meta-analyses. They state such studies have less oversight, are more susceptible to misconduct and are at greater risk of bias than larger, multicenter trials, and thereby skew conclusions of meta-analyses in favor of probiotics. They state, without evidence, that small trials are more likely to show large effects and are more likely to be published. They advocate for meta-analyses that only include multi-center trials, thereby ignoring much available evidence on the basis of unsubstantiated preferences. There are a number of reasons why some trials are multi-center, but improved quality or closer monitoring are not among them (see here, here and here). Multicenter trials may be necessary to study a rare medical endpoint, a condition with an expected small effect size but significant health implications, or to accelerate the time course for a study. In fact, an analysis of 81 meta-analyses of RCTs in 2012 concluded:

“Our results do not support prior findings of larger effects in SC (single-center) than MC (multi-center) trials addressing binary outcomes but show a very similar small increase in effect in SC than MC trials addressing continuous outcomes. Authors of systematic reviews would be wise to include all trials irrespective of SC vs. MC design and address SC vs. MC status as a possible explanation of heterogeneity (and consider sensitivity analyses).” [Emphasis ours]

 

In our experience, the size of a study does not inevitably minimize risk of bias. We have directly witnessed private physicians enroll for large multi-site trials without such oversight or professionalism. As the great David Sackett said in his paper from 20 years ago, “The more detailed the entry form and eligibility criteria for ‘somebody else’s’ RCT, the greater the risk the criteria will be ignored, misunderstood or misapplied by distracted clinicians who regard them as further intrusions into an overfull call schedule.” Further, due to often being underpowered, taken alone smaller studies are less, not more, likely to generate positive findings than larger trials. But when they are included in a meta-analysis, these studies contribute to the total body of evidence. We have personally worked on many single-center randomized controlled trials on probiotics. These often have monitors from the U.S. Food and Drug Administration and/or the National Institutes of Health, they are all registered with both primary and secondary outcomes listed, they utilize a data safety monitoring board, they undergo true allocation concealment, and otherwise are conducted to minimize risk of bias. To criticize probiotic studies for being single-center vs multicenter seems unjustified and baseless.

It is quite true that many of the studies conducted on probiotics were done 15 or more years ago, and the quality standards do not meet what we expect today. We wholeheartedly agree but would ask the authors to review studies conducted on drugs 15 years ago, and they will see the same issues. So we agree that more trials using modern quality standards are needed in the field of probiotics, as is the case for any interventions with a long history of being studied.

Claim 2: Potentially biased reviews of probiotic efficacy

In trying to explain why physicians might recommend probiotics, the authors speculate that some professional societies and some journals may be insufficiently critical in reviewing probiotic studies due to financial conflicts of interest. We have no doubt that there is bias in the scientific realm, which is not just limited to financial conflicts of interest, but question if there is any evidence that this occurs any more or less frequently with probiotics compared to any other realm of science. To leverage this accusation at the probiotic field specifically implies it is especially egregious, but no data supporting this accusation were provided. Also there is no face validity for this accusation. There is much more money to be made by pharmaceuticals and medical interventions than probiotic supplements and yogurts.

Claim 3: Complex framework in which probiotics are regulated and sold

The regulatory framework for probiotics can be difficult to navigate and is not always in the best interest of stakeholders, but we don’t think it’s reasonable to criticize the probiotic field for this situation. In the USA, probiotic products are bound by law that was enacted by Congress and the rules/guidance developed by the FDA for allowable product claims, levels of required regulatory oversight, and lack of requirements for premarket approval. It is fair to criticize Congress and the FDA for these circumstances surrounding the category of dietary supplements, but doing this in the context of an article on probiotics unfairly maligns probiotics.

Drugs vs dietary supplements. Most probiotics are sold as foods or dietary supplements. Since probiotics were first described as fermenting microbes in soured milk, this makes historical sense. Companies and consumers do not view these products as drugs, and in most cases they are not used as drugs. Outside a regulatory mindset, it makes perfect sense for foods to be useful for promoting health and managing symptoms, and this is what has driven 30 years of research and marketing of probiotics. Forcing all probiotics into a drug rubric would deprive consumers of access, would greatly increase their cost, and would preclude responsible food/supplement manufacturers from producing them. Drugs are drugs primarily to protect the safety of the patient. All drugs are assessed with a risk/benefit balance, and in some cases, the risk is significant. In the case of probiotics, we agree with the authors that most probiotics are likely safe for the general population. We see no reasonable justification to advocate that these products must all be researched and sold as drugs.

Probiotic product quality.The authors seem to prefer the drug model for probiotics based on a perceived need for improved product quality and oversight. Yet all foods and dietary supplements in the USA are required by law to be manufactured under good manufacturing practices. This includes most every product bought at the grocery store and served for dinner as well as probiotic foods and supplements. Further, companies are required to label their products in a truthful and not misleading fashion, including representations of contents and claims. Companies that fail to meet these standards are in violation of the law. Yes, there are products – of all types – that fall short of these requirements. The many responsible probiotic manufacturers and probiotic scientists decry such occurrences. However, these cases do not define the probiotic field any more than medical errors define physicians. It is not fair to impugn the entire probiotic industry based on the ‘bad apples’ that participate in it. A 2017 ESPGHAN review cites surveys of probiotic products from different regions globally, most of which report examples of probiotic products falling short in some quality attribute. Such surveys highlight quality problems, but due to sampling and methodological approaches, their results do not provide a reliable estimate of the extent of problem among commercial probiotic products. Many probiotic products are produced responsibly and are subjected to third party quality audits. The absence of such third party documentation is not evidence of poor quality, but we agree that it serves to improve consumer and healthcare provider confidence (see Jackson et al. 2019), and if more fully adopted, would weed out irresponsible probiotic manufacturers.

Oversight of probiotic research. The authors state, “If a manufacturer claims that any product, including a probiotic, cures, mitigates, treats, or prevents disease, the product is classified as a drug, thereby triggering a costly Investigational New Drug (IND) application process.” However, they seem to conflate the regulatory approach to product claims and the regulatory oversight of biologic drug research. In the case of product claims, if a product claims to cure, treat, prevent or mitigate disease, it is by definition a drug. If it has not undergone appropriate drug approval process, it is an illegally marketed drug and is subject to FDA action, including recall. Probiotics not destined for sale as drugs should not have to be researched under a drug rubric. This does NOT mean that such studies will de facto be substandard studies. We all understand the importance of conducting and reporting trials according to well-established guidelines. Studies on foods and supplements can and should follow those same principles.

Claim 4: Possible concerns about probiotic safety

Medical professionals balance potential harm with potential benefit for any intervention they recommend. Regarding safety of probiotics, the authors acknowledge that most probiotics are likely safe, but we would qualify that statement with “for their intended uses.” The use of probiotics in critically ill patient populations needs to be done with caution, proper oversight and a justification that the potential benefit will outweigh risk. The authors cite two examples to support their concern about probiotic safety, both in critically ill patient populations. One was a retrospective study looking at bacteremia in critically ill children (see the report here and responses to the report here and here). The second was a RCT that reported higher mortality in patients with pancreatitis (see the report here, with additional perspectives on interpreting safety outcomes here and here). We are not aware of any probiotics that are marketed for such uses, and if they were, they would be marketed as drugs, requiring drug-level safety and efficacy evidence. These studies are not an indictment of safety of probiotic foods and supplements, which in most cases are intended for the generally healthy population.

The authors further state that studies identifying adverse events from probiotics are the “tip of the iceberg” – creating an image of a huge number of unreported adverse incidents poised to be revealed. We have personally studied the most widely used Bifidobacterium strain, and in well over 30,000 pediatric patient days have not seen any serious adverse events and no more adverse events than placebo. The article cited by the authors states that our trials adequately reported harm. Obviously, no intervention is harmless, and no one claims as much for probiotics. It is true that older probiotic studies can rightly be criticized for not rigorously collecting and reporting data on adverse events (Hempel et al. 2011). However, a reasonable assessment of all available data, including data from well-conducted clinical trials, including trials in vulnerable populations, history of safe use, FDA notified assessments for GRAS use of certain probiotic strains, European Food Safety Authority QPS list, and others support that commonly used probiotics have a strong safety record for use in the general public.

Transferable antibiotic resistance. Regarding the risk that probiotics may transfer antibiotic resistance genes, this is a hypothetical concern – there is no documented case of this. Further, one pillar of probiotic safety assessments is that strains with antibiotic resistance genes flanked by mobile genetic elements are excluded from commercialization. As stated by Ouwehand et al. 2016, “Probiotics are specifically selected to not contribute to the spread of antibiotic resistance and not carry transferable antibiotic resistance.” The current approach to probiotic safety is that complete, well annotated genome sequences are available for commercial strains. This information is typically included in GRAS notices submitted to the FDA, and all the major probiotic suppliers require this level of safety assessment. This is the expected standard by the European Food Safety Authority as well, a standard that we enthusiastically and unreservedly endorse. Transferable antibiotic resistance is not a lurking threat of probiotics use, but is a well-considered issue adequately addressed by responsible probiotic manufacturers.

Conclusion

We believe that this JAMA viewpoint misrepresents the totality of data on probiotics and can potentially do harm by dissuading use of probiotics in an evidence-based manner. Important points have been raised by the authors, especially with regard to the use of probiotics in vulnerable populations, but this does not characterize most of probiotic use. We agree, as we expect the majority of scientists working on probiotics would, that additional, well controlled human studies are needed. That was why we were pleased to see the authors’ studies assessing the impact of L. rhamnosus R0011 and L. helveticus R0052 or L. rhamnosus GG on acute pediatric gastroenteritis, even though the results of both studies were null (see blog post regarding these studies here and here). But as we await additional trials, we have a responsibility to consider available evidence. The authors raise many good points that the entire medical field could learn from, but there are clear indications for probiotics and they should continue to be used for these indications, likely benefitting many while harming few.

Acknowledgements

MES and DM are grateful for the critical review of this perspective by probiotic safety expert Dr. James Heimbach, biostatistician Dr. Daniel Tancredi, and gastroenterologist and probiotic expert Dr. Eamonn Quigley.

 

 

 

Probiotics in fridge

The FDA’s view on the term probiotics, part 2: Further down the rabbit hole

/in ISAPP Science Blog, News /by KC

By James Heimbach, Ph.D., F.A.C.N., JHEIMBACH LLC, Port Royal, VA

A number of weeks ago I wrote on the ISAPP blog about US Food and Drug Administration (FDA) declining to file Generally Regarded As Safe (GRAS) notices that described the subject microorganism as a “probiotic” or “probiotic bacterium” (see The FDA’s view on the term “probiotics”). Now the FDA’s response to such GRAS notices has developed additional ramifications. Let me put them into two categories: Class 1 misdemeanors that will cause FDA to reject the notice, and Class 2 misdemeanors that will probably not prevent filing, but will cause FDA to raise questions. I should note that these thoughts are based on both my own direct experiences and my repeated telephone conference calls with FDA.

Class 1 Misdemeanors

  1. Using the term probiotic in any way in describing or characterizing the subject microorganism or its past, present, or intended use.
  2. Extended discussion of benefits derived from ingestion of the microorganism in animal or human research.
  3. Any mention, however brief, of the potential for the microorganism to be used in dietary supplements.

Class 2 Misdemeanors

  1. Including brief mentions of the microorganism serving as a probiotic. E.g., if you cite a study of the microorganism that you might previously have reported as “a study of the probiotic benefits” of the microorganism, change it to simply “a study of the benefits” of the microorganism. This same caution is advised when reporting opinions from the European Food Safety Authority (EFSA) or other authoritative bodies.
  2. Using the word “dose” in describing intended use. Also see #4 below.
  3. Virtually any use of the term “dietary supplement,” including in reporting past, current, or intended uses of the strain or the species in Europe or elsewhere, by anyone.
  4. Even relatively brief mentions of benefits. The recommended way of handling reporting of human studies of the species or strain is to avoid any narrative at all. Simply summarize the studies in tabular form, listing the citation, study design (RCT, open-label, etc.) and objective, study population (number, sex, age, characterization such as IBS patients, malnourished children, preterm infants), test article (microorganism binomial and strain), dose (but call it “administration level”—“dose” can be seen as indicating a drug or dietary supplement), duration, and safety-related results. Include methods used to ensure that any adverse events or severe adverse events would have been reported—medical examinations, self-report questionnaires, parental questionnaires, biochemical measures, etc.—and at what time points during or after the in-life portion of the research. Avoid ANY discussion of improvements seen in the test group.

Good luck!

The past decade of probiotics and prebiotics research: ISAPP board members share their perspectives.

/in ISAPP Science Blog, Consumer Blog /by KC

By ISAPP board members, compiled by Kristina Campbell

Scientific progress in the field of probiotics and prebiotics, as in any other field, often seems to occur one tiny step at a time. Yet over the course of several years, these tiny steps can add up to significant progress.

Current members of the ISAPP board of directors hold academic positions across North America, and Europe, representing some of the experts at the forefront of scientific innovation in probiotics and prebiotics. Their collective experience encompasses functional foods, fermentations, microbial ecology, microbial genetics, immunology, and clinical medicine, including pediatrics, family medicine and gastroenterology. As we enter into 2020 and a new decade, these board members have taken a moment to reflect on how far they and their colleagues have come over the past ten years, by answering the question: What changes have occurred in the domains of research, applications, and awareness about probiotics and prebiotics?

ISAPP board members, 2019 annual meeting

Available scientific methods and tools

The change that stood out the most to the ISAPP board members over the past decade was the rapid expansion of available scientific methods and tools – from gene sequencing technology to CRISPR-Cas to bioinformatic approaches. These exciting developments have enabled scientists to obtain more information, and to do it both quickly and economically. In the words of the board members:

“Advances in sequencing technology [have] revolutionized our ability to understand the gene repertoire of each individual probiotic strain (whole genome sequencing) and the interplay with the microbiome (metagenomics). This has been really energizing to the field, but has also meant that competence in bioinformatics has become an essential tool for probiotic and prebiotic scientists.”

“A decade ago, human studies on prebiotics would look at changes in the gut microbiota using fairly laborious procedures. Nowadays, the analysis is much more extensive and straightforward to do, and probably more accurate… The biggest change has been the capability to assess not only composition of the microbiota but also its functionality. So, today, the trials include metabonomics as well as assessments of health effects (through changes in particular symptoms and /or biomarkers such as blood lipids, microbial products, immune and inflammatory status). That way, we get a far better picture of what prebiotics can do.”

“In 2010 we only had DGGE to characterize the genome and were trying to figure out how to implement 16S amplicon sequencing. Now we are implementing shotgun & shallow shotgun sequencing for similar prices. In 2010, we did only work on 3-4 probiotic lactobacilli for molecular research, now we work on 400-500 lactobacilli. We do comparative genomics and functional analyses at much larger scale. And in 2010, we paid almost 10000 euro just to sequence one genome of lactobacilli, with limited analysis, now a few hundred euro for sequencing.”

Probiotics and prebiotics for microbiome modulation

Because of the rapid advancements in scientific tools and techniques during the past decade, as mentioned above, many more research groups are endeavoring to study the microbial communities that relate to probiotics and prebiotics. Gut microbiota are of great interest—not least because, among the strategies for microbiome modulation, probiotics and prebiotics are two of the leading candidates. Moreover, microbiome data can help researchers understand the context of probiotics and prebiotics in the gut and in different environments. In particular, many clinical trials of probiotics and prebiotics now include a microbiota-related measure. Novel species and strains for food use may be identified from gut microbiota studies, although safety and efficacy assessment will form challenges for regulatory bodies. Board members said:

“My collaborators and I initiated our first human clinical trials with prebiotics in 2008 and published several papers in 2010 and 2011. These early papers were among the first in which high throughput 16S DNA sequencing was used to assess how the human gut microbiota was affected by the prebiotic, GOS. Although this is now a routine method in the field, in 2008, having a Roche 454 pyrosequencer in the lab was very special, and we were astounded to be able to identify and measure abundances of the main members of the gut microbiota. Having these large data sets also led us to realize the importance of what was at the time the “new” field of bioinformatics that was critical in analyzing and reporting the data. This research showed that GOS was bifidogenic (with high specificity) in healthy adults, but was also subject-dependent. Thus, the results clearly showed there were prebiotic responders and non-responders. This remains an important area of research for my group.”

“The decade started with general excitement that ‘dysbiosis’ of the gut microbiota is involved in just about every human health problem, and has turned into re-remembering that correlation is not causation and microbiota patterns are often driven more by random factors or factors unrelated to disease than by microbiology.”

“It’s worth noting that in 2020, the well-controlled probiotic studies showing health benefits in humans are still more convincing and valuable than the studies showing any ‘beneficial’ effects on the human microbiota.”

“Over the past decade we have witnessed a tremendous explosion in our understanding of the microbiome and its interactions with us, its host. Progress in translating this knowledge into new treatments has been slower but glimmers of encouragement have appeared and we look forward to the next decade when interventions that modulate the microbiome to benefit our health will be based on a true understanding of how they act and will be selected to the maximal benefit of each individual.”

Probiotic mechanisms of action

Probiotic mechanisms of action are a perennial hot topic within the scientific community—and many had hoped that the new suite of scientific tools at scientists’ disposal would significantly advance this area of research during the past decade. But according to one ISAPP board member:

“In 2010 I would have confidently predicted that by 2020 we would have much more of a mechanistic understanding of probiotic mechanisms [and] the importance of strain effects… But this simply has not happened.  The field has become more biologically and computationally complex and many millions have been spent on research, but I still don’t think we can answer the fundamental question we faced in 2010, and in 2000, and in 1990 – what makes one a strain a probiotic, while another is not?”

But in the views of other board members:

“Through genomic and metabolomic studies we are identifying differences between strains that function at different sites and what properties are important for their probiotic function.”

“Identify[ing] the key effector molecules turned out to be more complex [than] we thought 10 years ago. It has become clear to me that probiotic mechanisms of action are per definition complex and multifactorial, because they are living microbes having thousands of molecules that all play a role. Yet, there is clearly an hierarchy of effector molecules.”

Probiotic and prebiotic applications

In general, microbiome studies of the past decade have led to a better appreciation of the ubiquity and complexity of microbial communities—not just those associated with different human body sites, but also those occupying every possible niche on Earth. ISAPP board members reflect:

“In 2010, I was mainly studying probiotics for the gut and vagina, now we have explored probiotics for the skin, respiratory tract, animals, plants, isolates from fermented vegetables that can boost vegan probiotic formulations etc., and other areas.”

“Two areas of research I am doing I’d never have imagined in 2010 are in honey bees and Chinook salmon and against environmental chemicals, administering probiotics.”

Public awareness of probiotics and prebiotics

Numerous studies and surveys show the general public has more awareness than ever of probiotics – and increasingly, of prebiotics too. Individuals receive their information through many different channels, both digital (e.g. blogs, websites) and non-digital (e.g. magazines, product packaging). The past decade also saw the creation of valuable evidence-based resources, such as the Clinical Guides available in the US and Canada, and resources from World Gastroenterology Organisation and from ESPGHAN (probiotics for pediatric acute gastroenteritis, pediatric nosocomial diarrhea, preterm infants, and pediatric AAD). These resources have been enabled by a critical mass of studies that have examined the efficacy of various probiotic strains for certain indications. One board member says:

“From a clinical perspective, the biggest change for us has been that the general public knows so much about probiotics; now we are doing a lot less educating of docs and patients about the concepts behind our probiotic studies.”

But there’s still work to be done:

“The term probiotic is now widely known, but still too often people are misinterpreting what it means, or generalizing the whole field instead of recognizing strain and product differences. We need to continue to educate and clarify to keep the messaging on track.”

“There is still lack of knowledge that not all probiotics are equal. The clinical effects and safety of any single probiotic or combination of probiotics should not be extrapolated to other probiotics. The same applies to prebiotics.”

“Choosing a probiotic continues to be a major hurdle for the consumer – for every probiotic strain that is well characterized, studied in detail in appropriate disease models, and shown to be effective in clinical trials there are hundreds that would fail to pass even the most basic tests of quality control. We must help the consumer to make informed choices.”

 

It seems that, while the past decade has been a fruitful time for probiotics and prebiotics research and public awareness, scientists still have a lot of work to do. In the 2020s they will use the tools available to them, and continue to develop new ones, to gain more detailed and multi-faceted information about probiotic strains and prebiotic compounds—and about the context in which they operate (for instance, the gut microbiome), to ultimately confer benefits on human health.

Misleading press about probiotics: ISAPP responses

/in ISAPP Science Blog /by KC

By Mary Ellen Sanders, PhD, Executive Science Officer, ISAPP

It seems over the last couple of years, open season on “probiotics” has been declared. Responding in a scientifically accurate fashion to misleading coverage, whether it is in reputable scientific journals or in the lay media, takes time and care.

I want to be clear: well-conducted clinical trials, regardless of the outcomes, are welcome contributions to the body of evidence. No one expects that every probiotic will work for every indication. Null trials document this – they tell researchers to look elsewhere for solutions. Further, we must acknowledge the limitations and weaknesses of available evidence; unfortunately, not all trials are well-conducted. We also need to be just as diligent in criticizing press that is overly positive about probiotic benefits, which are not backed by evidence.

However, articles with misleading information are all-too-frequently published. Below are ISAPP responses to some of these stories.

  1. A paper on rhamnosus GG bacteremia in ICU patients led to headlines about ‘deadly infections’ and probiotic administration ‘backfiring’, even though no patients died and clinical outcomes were not collected. ISAPP responded to clarify appropriate context for understanding the safety issues raised from this paper. See Lactobacillus bacteremia in critically ill patients does not raise questions about safety for general consumers.
  2. The Wall Street Journal published an article condemning probiotics for reducing fecal microbial diversity. ISAPP responded with a blog Those probiotics may actually be helping, not hurting, pointing out the errors in the author’s thinking (equating diversity with gut health).
  3. A pair of well-conducted clinical trials that did not show impact of probiotics on pediatric acute diarrhea led to some ignoring all previous evidence and concluding that no probiotics were useful for acute pediatric diarrhea. ISAPP responded about the importance of putting new evidence in the context of the totality of evidence: L. rhamnosus GG for treatment of acute pediatric diarrhea: the totality of current evidence. Also, Dr. Eamonn Quigley, an ISAPP board member, published an independent response.
  4. Pieter Cohen concluded that evidence for probiotic safety is insufficient in an article in JAMA Internal Medicine. ISAPP’s response was published in a letter to the editor, along with Cohen’s response to our letter.
  5. Responding to two papers in Cell (here and here), and accompanying media coverage that called into question probiotic safety and efficacy, ISAPP published a detailed post Clinical evidence and not microbiota outcomes drive value of probiotics objecting to conclusions, and released a public statement.
  6. Jennifer Abbasi wrote a critical article about probiotics with the inflammatory title “Are Probiotics Money Down the Toilet? Or Worse?” ISAPP responded with the following blog post: Probiotics: Money Well-Spent For Some Indications.
  7. When Rao, et al incriminated probiotics as a cause of D-lactic acidosis, ISAPP posted a blog and published a letter to the editor of Clin Transl Gastroenterol objecting to this conclusion.
  8. ISAPP responded to a paper claiming that probiotics were unsafe in children: Probiotics and D-lactic acid acidosis in children and Brain Fogginess and D-Lactic Acidosis: Probiotics Are Not the Cause.

Board member and Professor Colin Hill wrote a blog post called Another day, another negative headline about probiotics? His post provides some useful questions to consider when reacting to a publication:

  • Is the article describing an original piece of research and was it published in a reputable, peer-reviewed journal?
  • What evidence is there that the strain or strain mix in question is actually a probiotic? Does it fit the very clear probiotic definition?
  • Was the study a registered human trial? How many subjects were involved? Was it blinded and conducted to a high standard?
  • What evidence was presented of the dose administered and was the strain still viable at the time of administration?
  • Were the end points of the study clear and measurable? Are they biologically or clinically significant to the subjects?
  • Did the authors actually use the words contained in the headline? “Useless”, or “waste of money”, etc?

 

Effects of the food matrix on probiotic’s efficacy: how much should we care?

/in featured, ISAPP Science Blog /by ISAPP

By Gabriel Vinderola PhD, Researcher at the Dairy Products Institute (National Scientific and Technical Research Council – CONICET) and Associate Professor at the Food Technology and Biotechnology Department, Faculty of Chemical Engineering, National University of Litoral, Santa Fe, Argentina.

The issue of to what extent food components may affect probiotic efficacy when compared to the strain delivered as supplement has lately been the subject of debate. This is especially so in the context of the Codex Alimentarius guidelines on probiotics, presently under development.

When considering the importance of the food formulation delivering the probiotic, it’s worthwhile to keep in mind that people may get their daily probiotic together with an enormous variety of foods. For instance, one person may get the probiotic at breakfast along with a yoghurt or with cereal, whereas another person may choose to consumer a fruit juice, while a third may get the probiotic dose before a meal consisting of pasta, meat and vegetables. In those cases, the same strain can undergo gastrointestinal passage in the context of very different food exposures. Does this suggest that perhaps the specific food format is not so critical? What does research tell us?

An interesting, however in vitro, study was conducted by Grześkowiak et al. (2011). In this work, Lactobacillus rhamnosus GG was recovered from more than 12 foods and supplements and its ability to inhibit food pathogens was assessed in vitro. Authors showed that even when the inhibitory capacity was quantitatively different among isolates, the qualitative probiotic capacity of inhibiting pathogens was present in all of them. That is to say, the probiotic capacity had been retained to a somewhat greater or lesser degree, regardless the matrix.

Few human studies have measured to what extent a health endpoint changes when a probiotic is delivered in different food matrixes. For instance, Saxelin et al. (2010) showed that the administration matrix (capsules, yogurt or cheese) did not influence the faecal quantity of lactobacilli, but affected faecal counts of propionibacteria and bifidobacteria. However no health endpoint was considered in this study. Several studies demonstrate that dairy products are able to confer enhanced protection during gastrointestinal transit in in vitro settings (Vinderola et al., 2000; Sagheddu et al., 2018; da Cruz Rodrigues et al., 2019), suggesting that dairy products may be better at delivering an efficacious dose of probiotic. But again, no clinical endpoint was measured in these studies.

The first comparative study on the probiotic capacity of a strain delivered in food or supplement was reported by Isolauri et al. (1991). Authors demonstrated that Lactobacillus GG either in fermented milk or freeze-dried powder was effective in shortening the course of acute diarrhea. Later on, Meng et al. (2016) found similar patterns of immune stimulation when studying the impact of Bifidobacterium animalis subsp. lactis BB12 administration in yoghurt or capsules on the upper respiratory tract of healthy adults.

As these kinds of studies are scarce, we can look to meta-analysis where the same strain is compared for the same clinical endpoint, but in studies conducted by different groups in different matrixes. For instance, Szajewska et al. (2013) concluded that Lactobacillus GG delivered in capsules or fermented milk significantly reduced the duration of diarrhea and Urbańska et al. (2016) reported that L. reuteri DSM 17938 delivered in either capsules or infant formula reduced the duration of diarrhoea and increased the chance of cure.

In vitro studies find that survival of the probiotic delivered in different food matrices through a (simulated) gastrointestinal transit may quantitatively differ, but no matrix completely eliminates probiotic capacity. Human clinical trials comparing different matrices with a clear health endpoint are scarce, but a general conclusion seems to emerge: regardless of the food matrix, the probiotic effect is achieved.  When the data are assessed through meta-analysis, the top of the “levels of evidence” in the pyramid of evidence-based studies, the probiotic capacity exists for the same strain among different studies, conducted by different research groups, using different food matrices.

In many countries regulators require that the probiotic effect be demonstrated in the same food or supplement that will be offered to consumers. This is a conservative approach in the lack of other evidence, but it may be challenging at the same time for probiotic food development, as any new food, even similar to one already existing, may require new human clinical studies to demonstrate efficacy. This approach may raise economic and ethical concerns too, and be discouraging for the future of probiotics.

Surely additional clinical trials directly comparing effects among different delivery matrices would provide clarity on the importance of this factor to probiotic functionality. Until that time, regulators should enable probiotic food manufacturers to offer a sound scientific rationale that bio-equivalency of different matrices could be expected, and thereby circumvent the requirement need to re-conduct human clinical trials on probiotics delivered in new matrices.

 

References

da Cruz Rodrigues VC, Salvino da Silva LG, Moreira Simabuco, F, Venema K, Costa Antunes AE. Survival, metabolic status and cellular morphology of probiotics in dairy products and dietary supplement after simulated digestion. J Funct. Foods, 2019, 55, 126-134.

Grześkowiak Ł, Isolauri E, Salminen S, Gueimonde M. Manufacturing process influences properties of probiotic bacteria. Br J Nutr. 2011, 105(6):887-94.

Isolauri E, Juntunen M, Rautanen T, Sillanaukee P, Koivula T. A human Lactobacillus strain (Lactobacillus casei sp strain GG) promotes recovery from acute diarrhea in children.

Meng H, Lee Y, Ba Z, Peng J, Lin J, Boyer AS, Fleming JA, Furumoto EJ, Roberts RF, Kris-Etherton PM, Rogers CJ. Consumption of Bifidobacterium animalis subsp. lactis BB-12 impacts upper respiratory tract infection and the function of NK and T cells in healthy adults. Mol Nutr Food Res. 2016, 60(5):1161-71.

Pediatrics. 1991 , 88(1):90-7.

Sagheddu V, Elli M, Biolchi C, Lucido J, Morelli L. Impact of mode of assumption and food matrix on probiotic viability. J Food Microbiol. 2018, 2.

Saxelin M, Lassig A, Karjalainen H, Tynkkynen S, Surakka A, Vapaatalo H, Järvenpää S, Korpela R, Mutanen M, Hatakka K. Persistence of probiotic strains in the gastrointestinal tract when administered as capsules, yoghurt, or cheese. Int J Food Microbiol. 2010, 144(2): 293-300.

Szajewska H, Skórka A, Ruszczyński M, Gieruszczak-Białek D. Meta-analysis: Lactobacillus GG for treating acute gastroenteritis in children-updated analysis of randomised controlled trials. Aliment Pharmacol Ther. 2013 Sep;38(5):467-76.

Urbańska M, Gieruszczak-Białek D, Szajewska H. Systematic review with meta-analysis: Lactobacillus reuteri DSM 17938 for diarrhoeal diseases in children. Aliment Pharmacol Ther. 2016, 43(10):1025-34.

Vinderola G, Prosello W, Ghiberto D, Reinheimer J. Viability of  probiotic- (Bifidobacterium, Lactobacillus acidophilus and Lactobacillus casei) and non probiotic microflora in Argentinian Fresco Cheese (2000). J Dairy Sci. 2000, 83 (9), 1905-1911.

efficacyvseffectiveness

Efficacy and Effectiveness Studies

/in featured, ISAPP Science Blog /by Mary Ellen Sanders

By Michael D. Cabana, MD, MPH

In the world of clinical trials, reproducibility (or consistency) of results across different clinical trials improves clinicians’ confidence in an intervention (Hill, 1965).  However, when reviewing the evidence for a probiotic or prebiotic supplement, the results are sometimes conflicting.  One study claims an intervention may work.  Another study claims that an intervention may not work. So how does the clinician deal with this situation?

To know how much confidence to place in any claim of benefit, clinicians need to consider the totality of the evidence and the quality of the studies. One tool is the systematic review process, which in an unbiased manner searches for all studies for a particular intervention, and when possible, combines results into a meta-analysis. The ‘summary’ of these data point to either an effect or no effect. The best way to combine data is using an individual patient-data meta-analysis (IPDMA). In addition, a clinician should determine whether the clinical trial is an effectiveness study or an efficacy study (Singal 2014).

 

Efficacy or Effectiveness?   

Efficacy studies ask, “does the intervention work in a defined (usually an “ideal”) setting?”  In general, the inclusion criteria for study participants will be very selective.  Patient adherence tends to be closely monitored. The clinicians conducting the trial may be specially trained in the intervention and its application. The intervention occurs in an ideal setting and the risk of other confounding interventions (e.g., unusual diets, concurrent treatments) will be limited.

On the other hand, effectiveness studies ask, “Does the intervention work in a real-world setting?”  The inclusion criteria for study participants tends to be less selective.  Patient adherence to the protocol is not necessarily strictly enforced. The clinicians conducting the trial tend to be representative of the typical physicians who would treat this condition.  The intervention occurs in a more ‘real-world’ setting where the presence of other confounding factors may be present.

For example, two relatively recent studies both examined the effect of a probiotic intervention, L. reuteri DSM 17938 for the treatment infant colic.  A study conducted by a team in Italy (Savino et al. 2010) noted that the intervention reduced colic symptoms; however, the study conducted by a team in Australia (Sung et al. 2014) showed no effect on colic.

Why the different results? In the Italian study, all the infants were breastfed.  In addition, the breastfeeding mothers limited their dairy intake.  The infants tended to be younger (mean age 4.4 weeks) and tended not to have other treatments for colic or gastrointestinal symptoms.  In contrast, the infants in the Australian study were breastfed or formula fed. The infants were older (median age 7.4 weeks) and were more likely to have been exposed to other treatment for gastrointestinal symptoms (such as histamine-2 blocker or proton pump inhibitors).  The infants were recruited from many different settings such as the emergency department.

Although both the Italian and the Australian study evaluated the same probiotic intervention for the same condition, the studies offer different information in terms of efficacy and effectiveness.  Describing a study as either an “efficacy” study or an “effectiveness” study is not always dichotomous.  Rather, these studies exist on a spectrum, from being more like an efficacy study versus more like an effectiveness study. In the example above, the Italian study had stricter criteria and fewer confounding factors.  As a result, it would tend to be classified as an efficacy study.  The Australian study enrolled infants with colic who were older and had a greater likelihood to be exposed to other interventions.  This study would tend to be classified as more of an effectiveness study.  The fact that the Australian study was a null study does not mean that the intervention was not effective in the ‘real world’.  Rather, for the patients enrolled, the treatment was not effective when used in that particular setting and context.  Perhaps you may encounter infants with colic who have feeding history and medical history more like the infants from the Italian study. Understanding the context of the studies helps identify those characteristics that may or may not apply to the infants with colic who you may treat in your clinic.

 

Which is better: Efficacy or Effectiveness?

When developing a new or experimental intervention, an efficacy study might be important to increase the likelihood of detecting a positive change.  However, “real world” factors may make a difference in how a product is used.  Perhaps an intervention might be inconvenient (due to multiple doses throughout the day) or unpalatable for the patient.  Perhaps the dosing regimen is complicated and the primary care providers don’t apply the correct dosing for patients. In these cases, an effectiveness study might be a better guide to how useful the intervention will be in clinical practice.

As a final note, it can be tempting to simply read the abstract of a clinical trial to assess the results of a study.  However, in many instances the crucial details of the study (e.g., how the study participants were selected, who was included or excluded, what type of clinical setting was used) are buried in the methods section of the study.  Patient diet, exposure to other treatments and comorbid conditions are all common confounding factors encountered in trials evaluating supplements.  When reading through the literature and understanding if a study is applicable to your practice, be sure to understand the full context and purpose of the study.  “Was this study useful for determining clinical efficacy or clinical effectiveness?” is an important question for readers of probiotic and prebiotic clinical trials. Keeping this question in mind may help you better resolve what may appear to be inconsistency among clinical trials.