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Misera et al. Microbiome Res Rep 2024;3:48 https://dx.doi.org/10.20517/mrr.2023.81 Page 7 of 19

Psychobiotics in stress management
Psychobiotics are defined as live organisms (probiotics) and prebiotics that, when ingested in adequate
amounts, have a positive impact on the MGBA [62,63] . Animal studies have shown that gut microbiota
modified by probiotics, antibiotics (ABX), and gnotobiosis (germ-free model) might significantly alter
behavioral outcomes in rodents exposed to stress [64,65] . For instance, the intake of various probiotics was
[63]
demonstrated to improve stress-induced anxiety and depressive-like behaviors in mice . Therapeutic
strategies aimed at modulation of the MGBA were proven effective as novel treatment practices in future
psychiatric care. For instance, it has been well documented that administration of Lactobacillus helveticus
Rosell-52 to animals exposed to stress is associated with diminished pathogen adherence to intestinal
mucosa, decreased microbial translocation, and lowered synthesis of pro-inflammatory cytokines. These
events have been associated with a protective effect on the limbic system altered by chronic exposure to
stress [66,67] . In humans, such supplementation showed beneficial effects on mental health, including
alleviating stress and anxiety. Clinical trials have documented that the administration of Lactobacillus
helveticus Rosell-52 and Bifidobacterium longum Rosell-175 in healthy individuals has been associated with
decreased stress-related gastrointestinal symptoms. The oral use of these probiotic strains was associated
with better mood, lower perceived stress intensity, and decreased cortisol release [68,69] . Canadian Natural and
Non-prescription Health Products Directorate issued the following license approvals related to psychobiotic
use: a probiotic product composed of Lactobacillus helveticus Rosell-52 and Bifidobacterium longum Rosell-
175: (i) aids in lowering overall symptoms of anxiety; (ii) supports emotional balance; (iii) aids in the
management of stress-related gastrointestinal symptoms .
[70]
METHODS
The methodology for this study followed the scoping review framework initially developed by Arksey and
O’Malley , with subsequent updates . The study was conducted in five main phases:
[71]
[72]
1. Formulating the research question: The question posed was, “What is known about gut microbiota
alterations under the influence of A. muciniphila regarding its impact on health conditions in case of
prolonged exposure to stress?” This broad question covered as many aspects of the topic as possible.
2. Identifying relevant studies: We searched PubMed and Google Scholar databases using key terms such as
A. muciniphila AND (emotions OR psychiatric diseases OR psychopathology OR stress. Additionally, we
manually reviewed references from relevant reviews discussing the overall impact of A. muciniphila on
health. Only studies in English available by December 1, 2023, were included, with no restrictions on
publication date.
3. Selecting studies: We included studies involving animals and humans that provided data on the
intervention with A. muciniphila (live or pasteurized A or its components) to confer mental health benefits.
The first and senior authors conducted the selection process over two weeks.
4. Charting the data: Data were extracted from study protocols, including stress model type, intervention,
analytical techniques, key outcomes, conclusions, and limitations.
5. Collating, summarizing, and reporting the results: Data were thematically organized as paragraphs and a
Table.

At the beginning of the article, we added a paragraph describing stress response in humans and the impact
of stress on gut microbiota, the latter one being followed by a short communication on psychobiotics.