Meta-Analysis Suggests No Connection Between Probiotics And Reduced Anxiety


New research out of the University of Kansas suggests probiotic supplements might not be effective at easing anxiety symptoms.

For this study, researchers evaluated the results of over 35 preclinical trials looking at the correlation between probiotics and mental health in both human and rodent samples. According to this meta-analysis, there were no clear links between probiotics and improved mental health.

Lactobacillus rhamnosus was the only probiotic strain that appeared to have a positive effect on mental health. Study authors note, however, that L. rhamnosus only reduced anxiety symptoms in a rodent sample. L. rhamnosus is a common probiotic used in dairy products like yogurt and certain cheeses.

Investigators believe the rodents experienced a greater reduction in anxiety because they received a higher dosage of probiotics compared with humans. Due to the mice’s smaller size, whatever probiotics they ate were at least one order higher in magnitude than what humans took.

One slight issue with this meta-analysis is that psychologists did not diagnose the anxiety patients in these studies with mental disorders. Researchers in all of the studies only examined people who said they felt anxiety-like symptoms on a regular basis.

Study authors admitted that some of the human patients in these studies clearly didn’t suffer from severe anxiety. More research needs to be done to evaluate the possible benefits of probiotics on people with clinically diagnosed mental disorders.

Scientists involved in this meta-analysis reminded readers that research into probiotics is relatively new. While these findings suggest gut bacteria might not play a huge role in reducing mild anxiety, they don’t mean probiotics can’t be used to help people with psychological issues.

Over the past few years, probiotics have become one of the top selling supplements around the world. Recent statistics show that Americans spend at least $3 billion on these “beneficial bugs” every year. As probiotic advertising continues to increase, analysts believe these gut bacteria supplements could double within a decade.

Daniel J. Reis, a graduate student in the University of Kansas’ Clinical Psychology program, was the lead researcher on this study. A few other professors involved in this research include Drs. Stephen S. Ilardi and Stephanie E. W. Punt.

PLOS One recently published this review under the title, “The anxiolytic effect of probiotics: A systematic review and meta-analysis of the clinical and preclinical literature.”


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