Psychobiotics, gut microbiota and fermented foods can help preserving mental health

• Psychobiotics include a novel class of microorganisms that convey benefit upon the host's mental health via the dynamic microbiota-gut-brain crosstalk; • Gut microbes can regulate the expression of central neurotransmitter, related receptors and synthesize neurotransmitters; • The potential use of fermented foods as source of psychobiotics is gaining popularity among consumers for its possible therapeutic function on the brain. Psychobiotics include a novel class of probiotic microorganisms that convey benefit upon the host's mental health via the dynamic microbiota-gut-brain crosstalk. Research is bolstering the concept that gut bacteria are involved in the transmission of information between the gut and the brain, engaging neural, immune, and endocrine pathways. Factors such as diet, stress and aging can shape the microbiota composition in a process that may also influence the onset and development of mental diseases. This review aims to provide an outline of the link between the microbiota and brain function focusing on preclinical and clinical evidence of the potential application of psychobiotics in the context of the cognitive process and performance. The occurrence of metabolic precursors of neurotransmitters in foods that can be converted by the gut microbiota and play a role in the gut-brain axis are discussed. The understanding of the molecular mechanisms by which communication occurs is still at its infancy; however clinical studies have shown that dietary interventions based on psychobiotics might be a novel nutritional approach targeting gut microbiota for managing cognitive performance and preventing memory decline across lifespan.