A Narrative Review on the Advance of Probiotics to Metabiotics

An Advance from Probiotics to MetabioticsLactic acid bacteria (LAB), especially those with positive effects on health, are commonly known as probiotics, a term introduced by Nobel Prize winner, Elie Metchnikoff [11].Lactobacillus, Pediococcus, Leuconostoc, and Bifidobacterium are widely used as probiotics [12].Nevertheless, for application as a probiotic, microorganisms should have nonpathogenic and nonvirulent characteristics in relation to humans [13].Most probiotic applications have been reported in the prevention and treatment of diverse human diseases or disorders [2,14].Typically, probiotics should survive under intestinal conditions of low pH and high concentrations of bile salts, and show a high ability to adhere to intestinal epithelial cells [2,15].In addition, probiotics are known to have many health benefits as antioxidants, antivirals, anti-inflammatories, antimicrobials, as well as anticancer, cholesterol lowering, and anticavity drugs [16][17][18][19].Currently, many food and pharmaceutical industries are Recently, the term metabiotics has emerged as a new concept of probiotics.This concept entails combining existing probiotic components with metabolic by-products improve specific physiological functionalities.Representative ingredients of these metabiotics include short-chain fatty acids (SCFAs), bacteriocins, polysaccharides, and peptides.The new concept is highly regarded as it complements the side effects of existing probiotics and is safe and easy to administer.Known health functions of metabiotics are mainly immune regulation, anti-inflammatory, anticancer, and brainneurological health.Research has been actively conducted on the health benefits related to the composition of intestinal microorganisms.Among them, the focus has been on brain neurological health, which requires extensive research.This study showed that neurological disorders, such as depression, anxiety, autism spectrum disorder, Alzheimer's disease, and Parkinson's disease, can be treated and prevented according to the gut-brain axis theory by changing the intestinal microflora.In addition, various studies are being conducted on the immunomodulatory and anticancer effects of substances related to metabiotics of the microbiome.In particular, its efficacy is expected to be confirmed through human studies on various cancers.Therefore, developing various health functional effects of the next-generation probiotics such as metabiotics to prevent or treatment of various diseases is anticipated.