Data published in Cells indicated that Bifidobacterium longum R0175, Lactobacillus helveticus R0052, and Lactiplantibacillus plantarum R1012 supplementation for four weeks led to subtle improvements in depression ratings and sleep patterns in healthy young volunteers.
“The shown intervention-dependent changes in gray matter strengthen the hypothesis of potential probiotic effects on brain morphology, even in healthy subjects, and contribute to, in conjunction with brain connectivity changes, a greater understanding of the potential modes of action by which probiotics exert their effects via bidirectional gut–brain communication,” wrote scientists from Örebro University in Sweden, led by Dr Julia Rode.
“Even if the effects were subtle, the results also indicated more generally that the specific probiotic strains may have the potential to affect mental health.”
The study adds to the ever-growing body of science supporting the role of probiotics to beneficially impact the microbiota-gut-brain axis, that bidirectional interaction between the gastrointestinal tract and the nervous system.
Lead author, Dr Julia Rode told NutraIngredients: "Our study showed that this specific probiotic combination - aside from its long-known effects on gut health - has very specific effects on psychobiological parameters under normal day-to-day conditions (in humans)."
The study used the commercial probiotic product called Puraflow from GSK Consumer Healthcare. The product is available in Italy and contains the three strains at a total dose of three billion CFUs (colony forming units) at the end of shelf life. The product is also formulated with inulin, zinc, magnesium, potassium, glutathione and lactoferrin.
Earlier this year, a paper published in Nutrients indicated that the same product may help manage acutely stressful situations such as an arithmetic stress task. The new study looked at the resting state. In other words, there was no acute challenge.
The study was funded by Pfizer Consumer Healthcare (acquired by GSK in 2019) and the Swedish Knowledge Foundation.
The study included 22 healthy people with an average of 24 who were randomly assigned to either the probiotic product or placebo for four weeks. This was followed by a four-week washout period before the volunteers crossed over to the other group.
The double-blinded, randomized, placebo-controlled, crossover study used imaged the brain using Voxel-based morphometry, which showed that four weeks of probiotic supplementation led to changes in the volume of gray matter covering regions of the brain implicated in emotional regulation. These results corresponded well with data from questionnaires that indicated improved mood for the probiotic group, said the researchers.
These changes occurred without substantial changes in the gut microbiota composition, wrote Dr Rode and her co-workers.
“The probiotic intervention evoked distinct changes in brain morphology and resting state brain function alongside slight improvements of psycho(bio)logical markers of the gut–brain axis,” they wrote. “The combination of those parameters may provide new insights into the modes of action by which gut microbiota can affect gut–brain communication and hence brain function.”
Commenting on the potential mechanism(s) of action, Dr Rode and her co-workers noted that this may be via signaling molecules, such as BDNF and serotonin. These molecule “are part of a major route of communication between the gut, its microbiota-rich intraluminal ecosystem, as well as its enteric nervous system and the brain”, they noted.
Dr Rode added: "Although this study gave us some hints [about modes of action], we still do not know how the probiotics (this specific combination, but also in general) exert their effects on mental health aspects," she told us. "To further study this we might need to move into the investigation of more vulnerable study populations or employ multivariate approaches to look at the variety of our outcome parameters as a whole."