ABSTRACT
The probiotics definition stipulates the administration of an ‘adequate amount’ in order to obtain a health benefit. However, probiotic dose is not only relevant for efficacy; it is potentially also relevant from a safety perspective. Furthermore, there is the topic of number of strains included in a probiotic product. Products can be single-strain or multi-strain probiotics. The probiotic definition does not treat these two categories different, but a relevant question is whether there is a difference in their efficacy. For antibiotic associated diarrhoea there is ample evidence from specific dose-response studies and meta-analyses that higher doses provide a greater benefit. This could relate to the, convincingly documented increased faecal colonisation with higher doses. For other health benefits, the picture is less clear. This does not necessarily mean a dose-response does not exist; rather the current data is insufficient to draw conclusions. Likewise, for number of strains it appears difficult to draw a clear conclusion; there are too few studies that have compared single versus multi-strain products. For both dose-response and strain number, further studies would be necessary before conclusions can be drawn. As a short-term solution, sub-group analyses of dose and number of strain in meta-analyses could provide an indication.
