The research, published in the Nutrition Journal, said many reviews on probiotics had so far failed to justify this grouping together of strains. Another criticism of such reviews was the inclusion of poor quality studies, pooling heterogeneous study results and not considering publication bias.
According to the paper, multi-strain reviews could not confirm the benefit demonstrated was due to a specific strain or that the conclusions could be applied to probiotics more generally.
The study's authors said the strict application of a well-designed and -conducted systematic review would address such issues.
An EFSA favourite
They said the systematic review, which they called a "protocol-driven, transparent and replicable approach", had been favoured in the past by the European Food Safety Authority (EFSA).
“EFSA endorses the systematic review process to inform their judgement when deciding health claims, as observed with the decision on maternal folate intake and reduced risk of neural tube defects. This suggests the method is also suitable for probiotic health claims,” they wrote.
They added: "We propose that in certain well-considered situations, it is possible to pool results on different probiotics. Developing a scientific rationale based on substantial identity or common modes of action may justify such an approach. Although some probiotic functions are certainly strain-specific, we suggest conversely that not all probiotics function differently. When it is possible to link different probiotic strains by a common mechanism of action, pooling data on these strains may be appropriate."
Making a case
Last June DuPont-Danisco secured a rare probiotic gut health claim for its Activia Bifidobacterium lactis strain, stating that the product “contributes to digestive comfort by reducing transit time and bloating”.
Commenting on this latest research, technology leader for active nutrition at DuPont Nutrition & Health Dr Sampo Lahtinen told us that the company’s approach had been to provide strain-specific and condition-specific clinical evidence. He said that this did not exclude the possibility of also using systematic reviews and meta-analyses as additional evidence for the health benefits.
“Preferably the systematic reviews and meta-analyses should be focusing on the strain for which the claim is being made," he said.
The researchers from the York Health Economics Consortium in the UK, University Hospital Vall d’Hebron in Spain, University College Cork in Ireland and Dairy & Food Culture Technologies in the US received financial backing from the Global Alliance of Probiotics - an association that recently joined forces with the Yoghurt Live Fermented Milks Association (YLFA) to create the International Probiotics Association - Europe (IPA).
Meanwhile, EFSA issued official guidance on adequate immune and gut health claim dossiers earlier this week, which indicated the outcomes it felt could and could not be measured such as adhesion of E. coli to uroepithelial cells.
Source: Nutrition Journal
Published online ahead of print, doi:10.1186/s12937-015-0004-5
“A review of the systematic review process and its applicability for use in evaluating evidence for health claims on probiotic foods in the European Union”
Authors: J. Glanville, S. King, F. Guarner, C. Hill and M. E. Sanders