Psychobiotics is a term used in preliminary research to refer to live bacteria that, when ingested in appropriate amounts, might confer a mental health benefit by affecting microbiota of the host organism. Whether bacteria might play a role in the gut-brain axis is under research. A 2020 literature review suggests that the consumption of psychobiotics could be considered as a viable option to restore mental health although lacking randomized controlled trials on clear mental health outcomes in humans.

Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut microbiota. Probiotics are considered generally safe to consume, but may cause bacteria-host interactions and unwanted side effects in rare cases. There is some evidence that probiotics are beneficial for some conditions, but there is little evidence for many of the health benefits claimed for them.