Probiotics may ease anxiety: Pilot study

By Stephen Daniells

- Last updated on GMT

Related tags Lactobacillus casei Gut microbiota Gut flora

Supplements of Lactobacillus casei strain Shirota may ease symptoms of anxiety in people with chronic fatigue syndrome (CFS), according to new research funded by Yakult.

Two months of supplementation with the bacterial strain from a sachet was associated with a decrease in anxiety symptoms, according to findings published in the open-access journal Gut Pathogens​.

“These results lend further support to the presence of a gut-brain interface, one that may be mediated by microbes that reside or pass through the intestinal tract,”​ wrote the authors, led by Venket Rao from the University of Toronto.

The researchers admitted the research was preliminary and raises many questions regarding the mechanism of action. “The results of the present study should be viewed simply as a stimulus for further research,”​ they added.

The study was described as ‘interesting’ by probiotic expert Professor Gregor Reid from the Canadian R&D Centre for Probiotics at the Lawson Health Research Institute, and The University of Western Ontario. He also agreed that the study raises many questions.

“Do the gut microbiota (and probiotics) influence energy levels (which our own studies of HIV patients indicates is true) and by doing so is there an indirect effect on the brain and perception of how we feel? Do probiotics cause direct gut to brain signaling or indirectly via alterations in the overall microbiota that influence serotonin uptake? The latter seems unlikely as depression ​per se was not altered,”​ Prof Reid told

Study details

The Toronto-based researchers recruited 39 CFS patients and randomly assigned them to receive daily supplements of either Lactobacillus casei​ strain Shirota (24 billion colony forming units) or placebo for two months.

At the end of the study, the researchers reported significant increases in the faecal levels of both Lactobacillus​ and Bifidobacteria​ in people receiving the bacterial strain, compared to placebo. A significant reduction in the symptoms of anxiety was also recorded in the Lactobacillus​ group.

Further study

“Follow-up studies with probiotics should further examine specific gut microbes, intestinal structure and function as well as physiological markers associated with anxiety and depression,”​ wrote the researchers. “These may include inflammatory cytokines and other immune chemicals, blood tryptophan levels and urinary metabolites of neurotransmitters.”

Commenting on the findings, Professor Reid added: “I hope the researchers study each subject to try to understand when changes in anxiety occurred, what the triggers were and if these triggers occurred while on probiotics or placebo.

“Information from responders and non-responders could provide valuable insight into how real these findings are, and how confirmatory studies should be designed,”​ he said.

Yakult welcome

Commenting on the study, Dr Kudo, chief of science at Yakult Europe told "This is a very interesting study exploring how the axis between the gut and brain can affect health and mood. Positive outcomes were shown for chronic fatigue sufferers taking Lactobacillus casei Shirota (the probiotic strain in Yakult). A previous study in the UK with our strain also reported an association between consumption of this probiotic and improved mood in certain subjects.

“It should be noted that this was a pilot study but the results certainly indicate the need for further research in this area, and highlight the wide-ranging potential benefits that come from good gut health.

“This area of enteric neuroscience, which will be discussed further in June at the international Yakult symposium in Amsterdam, is very exciting. Prof. Bienenstock from McMaster University of Canada will discuss how the gut microbiota works together with the brain and nervous system to promote health and well-being.”

Source: Gut Pathogens​ 2009, 1:6 A randomized, double-blind, placebo-controlled pilot study of a probiotic in emotional symptoms of chronic fatigue syndrome”​ Authors: A.V. Rao, A.C. Bested, T.M. Beaulne, M.A. Katzman, C. Iorio, J.M. Berardi, A.C. Logan

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