Generally speaking, it may be good to recommend to customers a multi-strain probiotic as an every day supplement to support gut health. Most high quality, multi-strain probiotics contain around 5 or 6 different strains, so why not have 10 or 15? In theory, the more strains the better, right?

Well actually, not necessarily. In practice having 10-20 different strains in one supplement carries uncertainties. When it comes to probiotics, the question of survival is an important one, and when one product contains many strains, it is difficult to establish whether all of the strains will survive until the time of consumption. If you are considering stocking a probiotic supplement with a large number of different strains, make sure tests have been conducted to ensure the strains all survive together at the stated billions count until the time of expiry.

If we look at some of the world's leading, most trusted probiotic manufacturers, like the Institut Rosell, these supplements rarely offer more than 6 different probiotic strains in one capsule. Our partners at the Institut Rosell conduct rigorous tests on our OptiBac Probiotics For every day, to ensure the 6 different strains in this survive alive together in the capsule, at the billions count stated on the pack, until the end of the expiry date. All of the supplements in the OptiBac Probiotics range are tested to ensure they contain the number of billions of microorganisms, and the different strains stated on the pack, by the end of expiry. We cannot speak for other probiotic companies, but we do understand that it is extremely difficult to find numerous strains that survive together in one capsule, and tests proving the survival of 10+ strains in one supplement would be incredibly difficult to achieve. We would be very impressed to see these test results! To find out more about some of the tests we carry out, and to see some of the results, you may be interested to read nutritional therapist Joanna's blogpost about probiotic claims.

A review of the evidence:

In 2011, an independent review1 of clinical trials was carried out and published in the European Journal of Nutrition. The purpose of the review was to assess whether multiple strains of probiotics were more effective than single strains at ameliorating various health conditions. The results of the review were very much a 'mixed bag'. In certain instances a multi-strain formula performed better than a single strain did (from within the same formula), however in other trials greater efficacy was observed by using just a single strain of probiotic, rather than a multi-strain mixture.

One such study2 showed that when treating diarrhoea, associated with rotavirus in children, the single strain product of Saccharomyces boulardii on its own reduced the duration of the virus and the duration of the fever more effectively than did a mixed probiotic containing both Saccharomyces boulardii along with L. acidophilus, L. rhamnosus and B. longum strains. However the multi-strain product was more effective at preventing vomiting associated with the virus.

As you can see, there are no hard and fast rules. The quality of the probiotics strains used is by far the most important factor to consider when selecting a supplement that is right for you. Looking at the available clinical trials behind the strains will help you to select the right strain (or strains) for your specific health condition or symptom.

Specific strains for specific conditions

It is also worth noting that some of the most popular probiotic supplements on the market only contain one strain. These are known as 'single-strain probiotics'. One strain, like Saccharomyces boulardii for example, can absolutely suffice if it is the precise strain that works for a particular individual, for example S. boulardii is a great option for supporting health in patients with IBS-D. At OptiBac Probiotics we always state that individuals must find the right probiotic for them, and not just 'any old acidophilus'. If you are interested you can read more about strain-specificity and its importance.

At OptiBac Probiotics, our multi-strain supplements are formulated to target specific health conditions. We select each strain based on scientific studies and clinical trials, to ensure quality supplements tailored to your needs. In summary, for a high quality, scientifically tested multi-strain probiotic, take a look at 'For every day'. And bear in mind for future reference that far more important than asking the question 'Am I getting enough strains?' is the question 'Am I taking the correct strains for me?'

Find out more about our probiotics strains, or for further reading on the topic, take a look at 'The Numbers Myth'.


1. Health benefits of probiotics: are mixtures more effective than single strains? Authors and affiliations; M. C. Chapman, G. R. Gibson, I. Rowland.

2. Probiotics in the treatment of acute rotavirus diarrhoea. A randomized, double-blind, controlled trial using two different probiotic preparations in Bolivian children. Giuseppe Grandy, Marcos Medina, Richard Soria, Carlos G Terán and Magdalena Araya