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Meta-Analysis
. 2020 Sep;10(9):e01699.
doi: 10.1002/brb3.1699. Epub 2020 Jul 14.

Efficacy of probiotics on stress in healthy volunteers: A systematic review and meta-analysis based on randomized controlled trials

Ning Zhang  1   2 , Yanan Zhang  3 , Menglin Li  4 , Weiguang Wang  1 , Zhenzhu Liu  1 , Chongcheng Xi  1 , Xunying Huang  1 , Jintao Liu  1 , Junwei Huang  1 , Dong Tian  1 , Jie Mu  1 , Xing Liao  2 , Shuangqing Zhai  1
Affiliations
Meta-Analysis

Efficacy of probiotics on stress in healthy volunteers: A systematic review and meta-analysis based on randomized controlled trials

Ning Zhang et al. Brain Behav. 2020 Sep.

Abstract

Background: Probiotics seems to play a beneficial role in stressed populations; thus, a systematic review and meta-analysis to assess the effects of probiotics on stress in healthy subjects were conducted.

Methods: Randomized controlled trials on the effects of probiotics on stress in healthy subjects were retrieved from five databases. The effects of probiotics on subjective stress level, stress-related subthreshold anxiety/depression level, cortisol level, and adverse reactions were analyzed. Separate subgroup analyses were conducted on single-strain probiotics versus multi-strain probiotics, and short-term administration versus long-term administration.

Results: Seven studies were included, involving a total of 1,146 subjects. All the studies were rated as low or moderate risk of bias. Our research found that probiotic administration can generally reduce the subjective stress level of healthy volunteers and may improve their stress-related subthreshold anxiety/depression level, but no significant effect was observed in the subgroup analysis. The effect of probiotics on cortisol level was not significant. Adverse reactions were reported in only one of seven studies, but left undescribed.

Conclusion: Current evidence suggests that probiotics can reduce subjective stress level in healthy volunteers and may alleviate stress-related subthreshold anxiety/depression level, without significant effect on cortisol level, and there is not enough support to draw conclusions about adverse effects; thus, more reliable evidence from clinical trials is needed.

Keywords: gastrointestinal microbiome; healthy volunteers; meta-analysis; probiotics; psychological stress; systematic review.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

FIGURE 1
FIGURE 1
An adapted PRISMA Flow Diagram
FIGURE 2
FIGURE 2
Risk of bias for each included study
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FIGURE 3
The percent risk of bias for each included study
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Effect of probiotics on subjective stress levels
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FIGURE 5
Effect of single‐strain and multi‐strain probiotics on subjective stress levels
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Effect of short‐term and long‐term probiotic administration on subjective stress levels
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FIGURE 7
Effect of probiotics on stress‐related subthreshold anxiety/depression level
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FIGURE 8
Effect of single‐strain and multi‐strain probiotics on stress‐related subthreshold anxiety/depression level
FIGURE 9
FIGURE 9
Effect of short‐term and long‐term probiotic administration on stress‐related subthreshold anxiety/depression level
FIGURE 10
FIGURE 10
Effect of probiotics on the cortisol level
See this image and copyright information in PMC

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