Research from Duke-NUS Medical School and the National Neuroscience Institute of Singapore suggests that certain gut bacteria compounds, particularly molecules called indoles, could influence anxiety-related behavior by affecting brain activity involved in fear and stress. The findings point toward a potential future role for specially designed probiotics in anxiety treatment.
Scientists conducted preclinical experiments using germ-free mice—animals raised without exposure to live microbes—and found they displayed significantly more anxiety-related behavior than mice with typical gut microbe communities. The germ-free mice also showed heightened activity in the basolateral amygdala (BLA), a brain region involved in processing fear and anxiety. This elevated activity was linked to changes in calcium-dependent SK2 channels, proteins that help regulate how easily neurons become excited and fire.
When researchers introduced live microbes back into germ-free mice, activity in the basolateral amygdala decreased and anxiety-related behavior dropped substantially. The team tested indoles in isolation and found that when germ-free mice received these compounds, their anxiety-related behavior was similarly reduced. As Professor Sven Pettersson from the National Neuroscience Institute of Singapore explained, indoles appear naturally in breast milk and may represent an evolutionary mechanism by which newborns receive anxiety-regulating signals during their first exposure to life outside the womb.
The study, published in EMBO Molecular Medicine in February 2025, adds to growing evidence that mental health is not controlled by the brain alone, but rather through constant communication between the gut and brain. One practical approach could involve restoring microbial balance through dietary strategies, indole-based supplements, or probiotics containing indole-producing microbes. However, these possibilities remain experimental. Clinical trials will be necessary to determine whether indole-based probiotics or supplements can safely and effectively reduce anxiety in people. Later research has continued exploring whether probiotics influence mood and anxiety in humans, with results suggesting potential but varying effects depending on strain, dose, and individual baseline microbiome composition.
This article is an AI-assisted summary. All facts and figures are drawn from the original report: https://scitechdaily.com/the-probiotic-breakthrough-for-natural-anxiety-relief-and-better-mental-health/