It’s a phrase first coined in 2013 by researchers at University College Cork. Dr Gerard Clarke, one of the researchers from the original study, tells Stylist that the word refers to “the subset of probiotic strains of bacteria that could potentially modify brain function and behaviour”.

How do psychobiotics work?

Research shows that certain strains of bacteria can benefit stress, cognition (memory, specifically) and sleep. A 2016 paper showed that cortisol output and self-reported anxiety in participants were both positively impacted by strains of a bacteria called bifidobacterium longum 1714.

Other papers also show evidence of prebiotic organisms supporting cognitive performance, including a 2020 study that found participants who took a form of dietary fibre called polydextrose for four weeks produced a higher number of correct responses during a task.

Are psychobiotics the final key to linking gut health and mental health?