The consumption of some probiotic supplements appears linked to a reduced susceptibility to depressive symptoms, preliminary results of a randomized trial of 71 participants show.
“Results from the current study provide further evidence that some probiotic mixtures can influence thinking and cognition,” reported Bahia Chahwan of the University of Technology Sydney in New South Wales, Australia, and associates. “Although probiotics did not appear to have had a direct effect on depressive symptoms, our results suggest that probiotics potentially act on cognitive processes contributing to depression.” The study was published in the Journal of Affective Disorders.
To conduct the study, the investigators recruited 71 adults over a 12-month period. A nondepressed control group consisting of 20 adults was recruited over 2 months. Across both groups, about 70% of the participants were women, 67% were white, 80% had no abdominal conditions, 78% did not smoke, and 92% did not consume alcohol above the daily recommended intake. The participants were randomly assigned to either the probiotic or placebo group. Members of both groups received instructions on how to consume their respective product, which was a 2-g freeze-dried powder mixture, twice a day over 8 weeks, and were scheduled for weekly monitoring visits.
Several pre- and postintervention measures of depression were compared using several scales, including the MINI International Neuropsychiatric Interview, the Depression Anxiety Stress Scale-21, and the Beck Anxiety Inventory.
Participants in both groups experienced a reduction in depressive symptoms during the trial period. “This is in line with the evidence suggesting that , which forms the basis of activity scheduling as a component for [cognitive-behavioral therapy] for depression,” they wrote.
However, in contrast to the investigators’ hypotheses, participants in the probiotics group did not experience a greater reduction in depressive symptoms than did those on placebo. Instead, the differences between the groups were seen on a measure for depression called cognitive reactivity. Specifically, people with mild/moderate depression who took the probiotics reported lower psychological test scores on cognitive reactivity, compared with controls (45.00 vs. 53.78).
Additional research is needed to look at the impact of differences in gut microbiota strains on people with depressive symptoms, the researchers said. In the meantime, clinicians might do well to consider probiotics as an adjunctive intervention. “Probiotics may be a useful adjunct to potentiate the effects of therapies, such as CBT, which changes cognitive patterns.”
One of the authors, Saskia van Hemert, is an employee of Winclove Probiotics. The other authors reported having no conflicts of interest.
SOURCE: Chahwan B et al. J Affect Disord. 2019. doi: 10.1016/j.jad.2019.04.97.