Gut feelings: A randomised, triple-blind, placebo-controlled trial of probiotics for depressive symptoms.
BACKGROUND
Depression is the leading cause of disability worldwide; with evidence suggesting that decreased gut barrier function and inflammation are correlated with depressive symptoms. We conducted a clinical trial to determine the effect of consumption of probiotic supplements (Winclove's Ecologic® Barrier) on depressive symptoms in a sample of participants with mild to severe depression.


METHOD
71 participants were randomly allocated to either probiotic or placebo, which was, consumed daily over eight weeks. Pre- and post-intervention measures of symptoms and vulnerability markers of depression as well as gut microbiota composition were compared. Clinical trial participants were also compared on psychological variables and gut microbiota composition to a non-depressed group (n = 20).


RESULTS
All clinical trial participants demonstrated improvement in symptoms, suggesting non-specific therapeutic effects associated with weekly monitoring visits. Participants in the probiotic group demonstrated a significantly greater reduction in cognitive reactivity compared with the placebo group, particularly in the mild/moderate subgroup. Probiotics did not significantly alter the microbiota of depressed individuals, however, a significant correlation was found between Ruminococcus gnavus and one depression metric.


LIMITATIONS
There was a high attrition rate, which may be attributed to weekly monitoring visits. Additionally, modulation of the gut microbiota may need more specific testing to distinguish subtle changes.


CONCLUSIONS
While microbiota composition was similar between all groups, probiotics did affect a psychological variable associated with susceptibility to depression. Further research is needed to investigate how probiotics can be utilised to modify mental wellbeing, and whether they can act as an adjunct to existing treatments.
['Chahwan|Bahia|B|', 'Kwan|Sophia|S|', 'Isik|Ashling|A|', 'van Hemert|Saskia|S|', 'Burke|Catherine|C|', 'Roberts|Lynette|L|']
D000328:Adult D003863:Depression D019587:Dietary Supplements D005260:Female D000069196:Gastrointestinal Microbiome D006801:Humans D008297:Male D010919:Placebos D019936:Probiotics D012107:Research Design
Probiotics Depression Microbiota Cognitive reactivity Gut bacteria Gut-brain axis