• Disagreement with the proposed new definition of postbiotic: the ISAPP consensus statement1 proposes a common term to simultaneously indicate inactivated microorganisms and their specific products or components, which, in our opinion, generates confusion as well-defined molecular factors cannot be distinguished from complex (undefined) matrices derived from microbial cells.

• Review of the available scientific literature: the nomenclature adopted by the scientific literature in the past 10 years concerning inactivated microorganisms and their molecules and/or factors has been, in our opinion, mostly overlooked or misinterpreted. In particular, we believe the meaning most commonly attributed to the word ‘postbiotic’in scientific literature has been ignored.• Stability of products including inactivated microorganisms: the ISAPP’s document stated that “products with a long shelf life can be readily achieved for inanimate microorganisms” also in “geographical regions that do not have reliable cold chains or whose ambient temperature causes problems for storage of live microorganisms”, concluding that products containing inactivated microorganisms can “likely be extremely stable for several years at room temperature”. This claim is potentially unrealistic as the shelf life of any food, supplement or drug is influenced by its constituents (inorganic, organic or enzymatic) that inevitably participate to processes profoundly affecting stability (such as enzymatic modifications, Maillard reactions or oxidations), especially when temperature is not controlled, unsuitable packaging is implemented and/or improper storage conditions are adopted.