FAB RESEARCH COMMENT:
In this randomised controlled trial, participants taking a multi-strain probiotic for 6 weeks showed significant improvements from baseline on self-reported measures of depressive mood state, anger, fatigue, and sleep quality. No such significant improvements were reported b those receiving placebo.
The results of this trial do not meet standard criteria for showing benefits from an experimental treatment. That requires direct comparisons beween active and placebo groups to show a significant difference in 'change scores' from baseline, which was not the case here.
However, these findings are promising - and consistent with those from previous animal and some human studies.
The number of participants was relatively small, which matters, because for any given treatment effect size (i.e. the group difference) larger numbers would increase the statistical significance.
Larger trials therefore have more 'statistical power' to detect genuine group differences - and could help to assess whether the benefits for mood, sleep and energy levels seen here within
the group receiving probiotics may actually represent significant improvements compared with placebo treatment.
See the associated news article: