- There are multiple research reports suggesting that taking probiotics may have a positive effect on feelings of anxiety.
- The evidence score for anxiety is 60, and the reliability of the information can be considered moderate.
- Research is also underway on the relationship with mood and stress, but this is still at an investigative stage.
Probiotics refer to microorganisms that may have a beneficial effect on the human body.
They are generally taken through diet or supplements and are handled in the context of the gut environment.
It has been suggested that probiotics may ease feelings of anxiety.
In an analysis pooling the results of multiple studies, there is a report that anxiety was reduced among the participants. There is also a reported case involving 30 badminton athletes, studied continuously over 42 days. These are based on a meta-analysis (a method that statistically combines and analyzes the results of multiple studies) and randomized controlled trials (a reliable research method in which participants are randomly divided into groups to compare effects).
On the other hand, results for anxiety symptoms have not always been consistent. There is also a report that no significant difference was seen between probiotics and a placebo (a test method that uses a substance with no effect as a control) in easing anxiety symptoms. In other words, results are divided depending on the study.
There is a report of a positive effect on the mental wellbeing of older adults.
In a relatively small study involving 63 healthy community-dwelling older adults, differences were seen in scores for mental flexibility and stress. This study used a double-blind placebo-controlled trial (a rigorous experimental method, designed to prevent bias, in which neither participants nor researchers know which group they are in).
This study of older adults is a single study only, and reliability is limited. As can be seen from the scale of the data, this is still a stage where much more research is needed.
It is important to note that results differ between studies.
While some studies show a result of eased feelings of anxiety, reports of no observed change are also included. Taking probiotics does not necessarily act the same way for everyone.
In addition, much of this research was conducted over a specific period, and further verification of long-term effects is awaited. Because it may not suit some people, it is important to consider your own situation.
| Study | Design | Number of participants | Duration | Main result |
|---|---|---|---|---|
| Brain and Behavior (2025, PMID:40038860) | Meta-analysis | 4,295 people | Unknown | A positive effect was reported |
| Ciencia & Saude Coletiva (2021, PMID:34586262) | Systematic review | Unknown | Unknown | A positive effect was reported |
| Depression and Anxiety (2018, PMID:29995348) | Meta-analysis | 1,551 people | Unknown | No clear association was found |
| Frontiers in Immunology (2023, PMID:37033942) | Randomized controlled trial (RCT) | 60 people | 21 days | A positive effect was reported |
| Nutrients (2021, PMID:34073684) | Randomized controlled trial (RCT) | 30 people | 42 days | A positive effect was reported |
| The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences (2021, PMID:32300799) | Randomized controlled trial (RCT) | 63 people | 84 days | A positive effect was reported |
For research on anxiety, subjects included 4,295 study participants related to anxiety, 1,551 subjects who took part in randomized controlled trials (RCTs) concerning the easing of anxiety symptoms, 60 university students with test anxiety, and 30 badminton athletes (university students). For research on mood, 63 healthy community-dwelling older adults were the subjects.
These studies include people of a wide range of ages and conditions, from university students to older adults. This can serve as a reference for checking whether your own situation and age are included among the study subjects.
The research underlying this information consists of 6 studies in total.
The study designs used include meta-analyses, systematic reviews, and randomized controlled trials (RCTs).
For research on feelings of anxiety, it should be noted that conflicting results have been reported.
Can probiotics affect feelings of anxiety?
Studies have been reported showing a positive effect on feelings of anxiety. On the other hand, there are also reports showing no significant difference.
What effect might probiotics have on mood in older adults?
In research on healthy community-dwelling older adults, a possible positive effect on mood has been suggested. The reliability of this research result is limited.
What kinds of people are included in research on probiotics?
A diverse range of people are included in this research, such as university students, badminton athletes, and community-dwelling older adults. The subjects span a wide range of ages.
There are reports that probiotics have a positive effect on feelings of anxiety, but the results also show some variation. Research on mood is still limited, and further verification is needed. This content is based solely on academic research reports, and results differ depending on individual circumstances.
To get an objective sense of your own mental state, try using the self-check assessment as well.