Exploring the World's Most Researched Probiotic Strains

Aims of the Probiotics Database

More and more research demonstrates that the benefits of probiotics are seen at the level of the strain – ie. one strain may help with vaginal health, whilst another strain (even of the same species) might be much better researched for antibiotic associated diarrhoea.

At the same time, in this relatively novel field of health, a huge level of misunderstanding exists with regards to what a probiotic strain is – with many people thinking that Lactobacillus acidophilus is a probiotic strain – whereas it is in fact a species of bacteria, and identification at a strain level is imperative.

With this database we therefore aim:

About the Probiotics Database

Independent & Educational Resource

This is a non-commercial project, and is intended as an informative, educational tool and resource for healthcare professionals, health journalists and those with a particular interest in probiotics.

The probiotic strains included on the database are not limited to those in the OptiBac Probiotics range but have rather been independently identified by our team of nutritional therapists, as the most researched probiotic strains in the world. The strains have been chosen by both quantity of research behind them, but mainly by the quality of the research. By this we refer to the design of the studies, significance of the results, and of course population size studied.


Research on probiotics is a changing landscape with new studies being carried out and new strains being discovered. We aim to update the Probiotic Database accordingly and regularly. If you feel there is anything particularly missing feel free to let us know in the comments.

N.B.: Do note that this Database comprises a list of the world’s most extensively researched probiotic strains only, and therefore is not intended to encompass every single species or strain of bacteria within the Lactobacillus, Bifidobacteria & Saccharomyces genera.

Clinical Research

Please note also that we have focused on clinical research rather than in-vitro or animal studies. It’s safe to assume that all strains of probiotic bacteria documented have been thoroughly researched in-vitro for stomach acidity survival, adhesion and repopulation in the gut. If they were not performing in this way, it would be highly unlikely that these strains would have the results they do in the clinical trials detailed in this database.

We hope you find this a helpful resource! If so please share with your friends, link to it from your website and share it on social media. Please note also that this database is best viewed on desktop – so if visiting on mobile, please do bookmark it and come back when at your desk!

Research and consolidation by Joanna Scott-Lutyens, BA (hons), DipION, Nutritional Therapist; Kerry Beeson, BSc (Nut.Med) Nutritional Therapist; Megan Crowch, BSc (Hons) Physiology, Herbal Medicine Diploma (IRH practicing member); Laura Ryan, BSc (Hons) Psychology, DipCNM NT, mBANT, CNHC; and Dr Kate Stephens, PhD | Food and Microbial Sciences; Gut Microbiology (University of Reading), BSc (Hons) Medical Microbiology

Last updated - 17th May, 2019



  • This information will be very useful.
    During your research did you come across anything specific which correlates obesity and probiotics

  • Probiotic Professionals

    Dear Julie,

    Thank you for your query, and I'm so pleased that you're finding the Probiotics Database to be a valuable resource.

    The research studies we have listed relate only to the strains we have included in the Database, which comprises a premium selection of strains which we considered to be the most extensively-researched probiotics in the world. We have given an overview of their strengths based on the weight of research that supports their use, and for now, this does not include obesity and weight management. Whilst there may be studies in the field that are looking at the effects of probiotics in weight management, as yet, the research is still in its infancy and very little, if any, research into the effects of probiotics on obesity has been carried out on the specific strains that we have listed in the Database.

    If you are looking to advise clients regarding gut health and weight management, until more evidence on specific strains is available, we would advise focusing on overall gut health and a optimising digestive function.

    With kind regards,


  • I would sincerely like to express my gratitude towards you for assembling probiotic database and providing information which is very helpful.

    Thank you

  • You guys should look into Lactobacillus Fermentum ME-3. It has a few clinical studies on oxidative stress markers, increasing PON1, Glutathione, and even fighting pathogen.

  • Probiotic Professionals

    Dear John,

    Thank you for your comment and suggestion.

    We're always looking out for interesting and extensively researched strains to add to our ever-growing database, so we appreciate your suggestion!

    Thanks again for your comment.

    With best wishes,


  • What an incredible tool on all things probiotic! As a GP in the NHS, I'm disappointed with the lack of access to information about probiotics and the research behind them. Many of my colleagues are unaware that probiotics have seen any clinical trials. Having started my research journey (prompted by a few patients with unrelenting IBS symptoms) I'm very impressed to find this resource, so thank you, and I hope you are able to keep up the great work.

  • Probiotic Professionals

    Dear Miranda,

    Thank you so much for your feedback. We really appreciate it and we're glad you've found the database useful.

    With best wishes,


  • Dear OptiBac Team,
    I am glad and grateful to find this probiotic database, which is very simplified and informative. I am not sure whether you have come across with the role of Lactobacillus gasseri SBT2055 in weight loss. Here are few human studies (PubMed ID: 23614897, 25884980, 20216555), indeed there are also other, including animal studies.

    Kind regards,
    Dr. Tewodros

  • Probiotic Professionals

    Dear Dr. Tewodros,

    Thank you for your comments and suggestions, and for you interest in our Probiotics Database.

    We are constantly reviewing the emerging research and looking for new strains which meet the criteria for inclusion in this resource. Although there are some incredibly interesting developments in this field, for the Database we look for strains which are supported by the largest weight of clinical evidence.

    Thank you again for your suggestions, and we greatly appreciate you taking the time to leave your comments.
    Kind regards,


  • Congratulations on publishing this valuable and well structured resource!
    One suggestion. Sensitivities to biogenic amines and D Lactate produced by some strains seem to be more widespread than originally thought. Could you possibly include information about which strains produce these?
    Do you plan to include information on a wider range of species? For example, quite a few studies have come out on B. Longum, including its possible impact on depression.

  • Probiotic Professionals

    Hello Mark,

    Thank you so much for your comments and positive feedback regarding the Database. We really appreciate this, and value your suggestions.

    I can understand the reasoning behind your suggestions, as there is a lot of interest into the histamine and D-lactate producing potential of probiotics; however, we don't feel that it would be appropriate to include this information on the Database. The purpose of the Database is to document the world's most researched strains of probiotic bacteria, focusing particularly on areas where strains have seen a lot of published research for relatively common health conditions. This aids healthcare practitioners to select the best strains of bacteria for their clients. The other consideration is that, even if we wanted to add this information, many of the strains may not have been specifically tested for these abilities, or the information may be proprietary and unavailable.

    We have offered a brief overview of the characteristics of each genus, species, and strain that we feature, to give some context, but we particularly want to focus on the clinical studies that support each of the strains featured. We could include a wealth of information regarding the characteristics of each bacterial strain, including all of the related in vitro studies, but the Database is not intended to be this type of resource; we just wanted to highlight those probiotic strains which are supported by the greatest number of clinical trials, which we feel is the mark of a quality probiotic.

    To answer your second question regarding research into the Bifidobacterium longum species: I expect that you’re referring to the Bifidobacterium longum 1714 strain, which has been featured in various studies looking at the effects of probiotics on mental health. We are constantly reviewing the emerging research, and identifying strains which deserve to be included in a list of the world’s most researched strains, and so you can expect to see new strains being added to the Database in the future. Although there are some incredibly interesting developments being made in many areas of probiotic research, we’ll only include strains which are supported by numerous gold-standard clinical trials.

    Thank you again for your valued feedback and your interest in our resource, and I hope that this helps to clarify its intended purpose.

    With kindest regards,


  • This page is amazing and useful for us. We can search specific probiotics strain very easily.
    Thank you for your kindness.

  • Probiotic Professionals

    Dear GiDuk,

    Thank you so much for taking the time to leave your comments. We're delighted that you have found the Probiotics Database useful.

    With best wishes,


  • PA student in the United States, I appreciate your team's compilation of evidence-based medicine and have taken valuable notes that will aid me in guiding future patients who are willing to incorporate probiotics in their treatments.

  • Probiotic Professionals

    Hi there Ricardo,

    Thank you so much for your positive feedback, we are so pleased that you're finding the database useful.

    Wishing you the best of luck with the continuation of your studies.

    With kindest regards,


  • Thanks for this excellent resource. Strain specificity is not well understood and is taken advantage. Patenting and marketing of probiotics is in general, about profit before health and there are any players in the current market. Looking forward to new strains being added to this Database in the future.

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