Probiotics act as a mood booster for healthy adults

It is becoming increasingly clear that there is far more to our organs than simple breakdowns and food digestion.

In recent years, research has repeatedly shown:

Now new paper It's just been published on NPJ Mental Health Research They argue that probiotics can fight back against negative emotions, at least in healthy adults.

“The gut-brain connection provides a variety of routes where bacteria in the gut can affect how we feel and behave through the vagal nerve, immune system and hormones,” said co-author and research associate in the Department of Experimental Psychology at Oxford University.

This study provides some new information on how probiotics affect our mental health.

“We found that a variety of traits, particularly the trends in risk aversion, are associated with the greater effects of probiotics on mood,” Johnson added.

Methodology

The researchers recruited 88 healthy young adults. They relied on a randomized, double-blind, placebo-controlled design to explore how multi-species affect emotional regulation and mood. Throughout the four-week survey, participants ran through a series of assessments. They included psychological surveys, emotional processing tasks, and daily mood ratings.

Standard psychological questionnaire revealed little change in the emotional state of participants after a probiotic intervention. However, daily mood tracking provided a revelation. Researchers have noticed a clear and consistent decline in negative moods in people taking probiotics. This was the first trend the author noticed during his research.

“It's impressive to see that just asking participants how they feel every day can detect the beneficial effects of probiotics on mood,” said Dr. Laura Steenbergen, an assistant professor at Leiden University. “In contrast, the standard psychological surveys common in this area were not as sensitive as addressing these changes.”

The greater meaning of probiotics

This study highlights the growing importance of methodological design in assessing mental health interventions. Traditional tools such as symptom surveys are effective, but may miss some of the more subtle changes in emotional experiences. For example, this particular study has provided a high-resolution view of participants' emotional trajectories.

The meaning can be enormous. As public interest in gut health accelerates and mood disorders increase worldwide, more people recognize it as a potential tool to support mental well-being.

Interestingly, the researchers also identified psychological traits that predict who benefited most. Participants who scored higher risk aversion – traits associated with vulnerability to depression – were more likely to experience a decrease in negative mood. This suggests that probiotics may offer the greatest benefits as an early intervention strategy.

Although probiotics did not make much difference in cognitive tasks, the authors noticed signs that they might increase emotional awareness. In one example, the authors discussed that the probiotic group accurately recognizes facial expressions and shows slight improvements, suggesting the possibility of emotional processing.

In particular, the timeline is similar to the traditional antidepressant timeline, which usually takes about two weeks to control symptoms. Probiotics and antidepressants work differently, but researchers point out that both can affect mood through anti-inflammatory effects and neural pathways.

Dig deeper

Finally, the authors suggest that probiotics may provide subtle yet meaningful mental health benefits to the general population. Specifically, this study opens the door to the use of targeted probiotics. It suggests that probiotics may function as a mental health support strategy. This approach may help to stem the onset of more serious conditions.

“Perhaps in the future, probiotics could be used in targeted ways as early interventions to reduce the likelihood of negative emotions that progress to mental health conditions such as depression, but more research is needed to confirm that,” Steenbergen proposed.

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