Table 3

The risk of key biases present within each study

Author, yearRandom sequence generationAllocation concealmentSelective reportingOther biasesBlinding of participants and personnelBlinding of outcome assessmentIncomplete data outcomeAdditional information
Rudzki et al (2019)20LowLowUnclearLowLowUnclearHigh19 lost to follow-up; information concerning these individuals not included in report
Majeed et al (2018)23UnclearUnclearLowHighUnclearUnclearLowAuthors employed by manufacturer of the intervention—Sabinsa, USA. Sabinsa also funded the trial
Kazemi et al (2018)21LowLowLowLowLowUnclearHighAttrition bias present; however, all subjects accounted for and details of loss to follow-up well explained
Miyaoka et al (2018)24UnclearHighLowUnclearHighHighLowRandom group allocation insufficiently detailed; open label design (no blinding).
Ghorbani et al (2018)25LowLowLowLowLowUnclearLowIndependent company employed for randomisation protocols, no loss to follow-up. Blinding of results unspecified
Bambling et al (2017)26N/AN/ALowHighHighN/AHighNo randomisation or control group. Patients and investigators knew what intervention was. Patients lost to follow-up (accounted for). Potential conflict of interest—researchers work with companies that seed fund, produce and research probiotics
Akkasheh et al (2016)22LowUnclearLowUnclearUnclearUnclearLowRandomisation of groups and allocation claimed to be done; claimed outcomes were blinded, though no explicit details provided (therefore unclear). Attrition bias, participants included in analysis with intention-to-treat approach. Conflict of interest not stated