Abstract
Traditionally, probiotics on the base of live microorganisms are considered to be both beneficial and safe. Unfortunately, their effects may have short-term success or are absent or uncertain. Some symbiotic (probiotic) microorganisms with known beneficial health affects may cause opportunistic infections, increase incidence of allergic sensitization and autoimmune disorders, produce microecological imbalance, modify gene expression, transfer antibiotic resistant and virulence genes, cause disorders in epigenome and genome integrity, induce chromosomal DNA damage, and activate signaling pathways associated with cancer and other chronic diseases. The commercially available probiotics should be considered as a first generation means of correcting microecological disorders. Further, their development will include the selection of natural metabiotics and/or working out the synthetic (or semi-synthetic) metabiotics that will be analogies or improved copies of natural bioactives, produced by symbiotic (probiotic) microorganisms. Metabiotics are the structural components of probiotic microorganisms and/or their metabolites and/or signaling molecules with a determined (known) chemical structure that can optimize host-specific physiological functions, regulator, metabolic and/or behavior reactions connected with the activity of host indigenous microbiota. Metabiotics have some advantages because of their exact chemical structure, well dosed, very safe and long shelf-life. Thus, now metabiotics should not consider myth; they are the result of the natural evolution of probiotic conception.