How many strains is ideal in a probiotic supplement?
Probiotic supplements containing more than one strain of bacteria are commonly referred to as 'multi-strain' supplements, or sometimes as 'poly-strain' or 'polybiotics'.
Generally speaking, a multi-strain probiotic can be a good option as an every day supplement to support gut health. Most high-quality, multi-strain probiotics contain around 5 or 6 different strains1, but 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 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 expiry.
What does the research say?
'the benefits of multi-strain mixtures may include broader range of effects and more mechanisms of action...'There are clearly pros and cons for single and multi-strain probiotics - the former more stable, the latter has the potential to be more effective, dependent on the strains used and condition being targeted.
For Helicobacter pylori, for example, a single strain leads to a 0.66 day reduction in diarrhoea, whilst a two-strain mix leads to a 0.41 day reduction. In this instance, the single strain has been more effective but importantly, 'these are both significant reductions'. And whilst there is no definitive answer it is clear that more research is needed. Some of the most popular probiotic strains on the market only contain one strain. These are known as 'single-strain probiotics'.
Saccharomyces boulardii (S. boulardii) on its own, for example, can be a great option for supporting people with IBS-D. In fact, a study3 published in 2010 found that when treating diarrhoea, associated with rotavirus in children, S. boulardii reduced the duration of the virus and the duration of the fever more effectively than did a mixed probiotic containing both S. boulardii along with L. acidophilus, L. rhamnosus and B. longum strains. It is worth noting, however, that the multi-strain product was more effective at preventing vomiting associated with the virus.
Specific strains for specific conditions