“Probiotics can improve mood and anxiety.”
Limited confidence. Some randomized trials and meta-analyses report improvements, especially in people with depression, but products, strains, doses and populations differ greatly and statistical heterogeneity is very high.
Certain probiotic or related microbiome interventions may modestly improve depression or anxiety symptoms in some studied groups, but the evidence does not show that probiotics as a broad category reliably treat mood or anxiety disorders.
A probiotic is a specific live strain at a specific dose, not a single interchangeable treatment. Results for one product cannot automatically be applied to another, and prebiotics and synbiotics are different interventions.
Safety note: Probiotics usually cause mild gastrointestinal effects in healthy people, but rare serious infections have occurred. Risk is higher with severe illness, immune compromise, critical illness, premature infancy or a central venous catheter.
Talk to a healthcare professional if: Ask before using probiotics if you are immunocompromised, seriously ill, hospitalized or have a central line. Persistent depression or anxiety deserves clinical assessment, and suicidal thoughts require urgent support.
Do not replace established mental-health treatment with a probiotic. A product may be reasonable for some healthy adults, but benefit is uncertain and label quality and long-term safety vary.
If you want to try one, discuss the specific product and goal with a clinician, especially if you take medicines or have significant illness. Track symptoms and stop if it causes problems.