Psychobiotic Effects on Anxiety Are Modulated by Lifestyle Behaviors: A Randomized Placebo-Controlled Trial on Healthy Adults

Psychobiotics are modulators of the Microbiota-Gut-Brain Axis (MGBA) with promising benefits to mental health. Lifestyle behaviors are established modulators of both mental health and the MGBA. This randomized placebo-controlled clinical trial (NCT04823533) on healthy adults (N = 135) tested 4 weeks of probiotic supplementation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175). We assessed effects on wellbeing, quality of life, emotional regulation, anxiety, mindfulness and interoceptive awareness. We then analyzed if lifestyle behaviors modulated probiotic effectiveness. Results showed no significant effects of probiotic intake in whole sample outcomes. Correlational analyses revealed Healthy Behaviors were significantly correlated with wellbeing across scales. Moreover, the linear mixed-effects model showed that the interaction between high scores in Healthy Behaviors and probiotic intake was the single significant predictor of positive effects on anxiety, emotional regulation, and mindfulness in post-treatment outcomes. These findings highlight the relevance of controlling for lifestyle behaviors in psychobiotic and mental health research.

Automated summary

Psychobiotics, as modulators of the Microbiota-Gut-Brain Axis (MGBA), have promising benefits for mental health. This clinical trial examined the effects of probiotic supplementation on wellbeing, quality of life, emotional regulation, anxiety, mindfulness, and interoceptive awareness in healthy adults. Results showed no overall effects of probiotic intake, but the interaction between high scores in Healthy Behaviors and probiotic intake was a significant predictor of positive effects on anxiety, emotional regulation, and mindfulness. This highlights the importance of controlling for lifestyle behaviors in psychobiotic and mental health research.