The study is said to be the first to show chronic intake of a fermented milk product with probiotics can alter brain activity in humans, wrote the researchers in Gastroenterology​​.

“Even though a possible relationship between the gut microbiota profile and mood has been postulated based on preclinical data, and a recent report in IBS patients provides further support for such a hypothesis, this study is the first to demonstrate an effect of fermented milk product with probiotics intake on gut-brain communication in humans,”​​ wrote the researchers, led by UCLA’s Kirsten Tillisch.

Commenting independently on the new study, Prof Glenn Gibson, a world-renowned expert in pre- and probiotics at the University of Reading in the UK, told us: "There is evidence that the gut to brain axis exists, with positive and negative potential outcomes. However, modulating it like this is a big step forward."​

According the FAO/WHO, probiotics are defined as "live microorganisms which when administered in adequate amounts confer a health benefit on the host"​.

Beyond the gut - A big step forward​

The majority of the science for probiotics has focused on gut health, but as the understanding of the gut and the microbiome increases, probiotics are increasing linked to a range of beneficial effects, from weight management to immune support and allergy response, and from oral health to cholesterol reduction​.

Data from rodent studies has indicated that modification of the gut microbiota can alter signaling mechanisms, emotional behavior, and instinctive reflexes.

The new study examined the role of a fermented milk product with probiotics containing Bifidobacterium animalis​ subsp. Lactis, Streptococcus thermophiles​, Lactobacillus bulgaricus​, and Lactococcus lactis​ subsp. Lactis on brain connectivity or responses to emotional attention tasks in women.

Study details​

Tillisch and her co-workers recruited 36 healthy women with no gastrointestinal or psychiatric symptoms, and randomly assigned them to one of three groups: The first group received the probiotic yogurt, the second group received plain yogurt with no probiotics, and the third group received no intervention two times per day for four weeks.

Results showed that the probiotic yogurt was able to change the responsiveness of an extensive brain network in healthy women.

“As a proof of concept it has been successful in showing that such communication exists and is modifiable, even in healthy women,"​ ​wrote the researchers.

“Further examination of these pathways in humans will elucidate whether such microbiota to brain signaling plays a homologous role in modulating pain sensitivity, stress responsiveness, mood or anxiety as previously reported in rodent models.​

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“Further, identification of the signaling pathways between the microbiota and the brain in humans is needed to solidify our understanding of microbiota gut brain interactions. ​

“If confirmed, modulation of the gut flora may provide novel targets for the treatment of patients with abnormal pain and stress responses associated with gut dysbiosis,” ​they concluded.

The study was funded by Danone Research.

Source: Gastroenterology​​

Published online ahead of print, doi: 10.1053/j.gastro.2013.02.043

“Consumption of Fermented Milk Product with Probiotic Modulates Brain Activity”​

Authors: K. Tillisch, J. Labus, L. Kilpatrick, Z. Jiang, J. Stains, B. Ebrat, D. Guyonnet, S. Legrain-Raspaud, B. Trotin, B. Naliboff, E.A. Mayer