With promoting awareness of health around the world, the consumers attached highly importance to food quality and dietary supplements. More and more people maintain the state of health through dietary supplements. Several studies have reported that the gut microbiome of human is gradually affected by the metabolites, microbial characteristics, and the composition of the microbiota, which affects the physiological functions and the digestion. Probiotics are one of the beneficial microorganisms which can maintain the composition of gut microbiota, promote the absorption of nutrient and improve the immune system. With the increasing demands for dietary supplements contained probiotics, more and more importance has been attached to the quality and safety of probiotics.
 
Organization (WHO) and the Food and Agriculture Organization (FAO) proposed the redefinition of probiotics in 2014 which was “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”. The four following standards that determine whether microbes have qualified to be probiotics or not were reiterated in 2018 by the International Scientific Association of Probiotics and Prebiotics (ISAPP) in a position statement. Probiotic strains must be (1) sufficiently characterized; (2) safe for the intended use; (3) supported by at least one positive clinical trial conducted according to generally accepted scientific standards or as per recommendations and provisions of local/national authorities when applicable; (4) alive in the product at an efficacious dose throughout shelf life.。
 
(1) Sufficiently characterized.
The key component of correct probiotic characterization is proper strain identification and naming. Sequencing of the 16S ribosomal DNA and whole genome sequencing (WGS) are well-known and reliable way to identified species. Through the database, the identity and the relatives with other species of stains could be confirmed.
 
(2) Safe for the intended use.
The European Food Safety Authority (EFSA) has maintained lists of microorganisms presumed to be safe for human consumption in foods under the “Qualified Presumption of Safety” (QPS) concept as the unified risk evaluation of microbial products since 2007. The list is a basis for establishing safety of food strains when belonging to a QPS species with the strain-specific testing. Besides QPS, other countries also provide the food safety procedures to evaluate the safety of probiotics, such as “generally recognized as safe” (GRAS) of US.
 
(3) One positive clinical trial.
In order to prevent the probiotics from safety concerns, at least one human trial demonstrating a health benefit is required to qualify the candidate microbial strains for probiotic status. Therefore, there are no major safety concerns for their use in foods and dietary supplements for the general population.
 
(4) Alive in the product at an efficacious dose throughout shelf life.
Sufficient levels of the probiotic strains must be contained in the final product throughout the shelf life in order to be able to deliver the claimed health benefit. Products should be manufactured according to applicable good manufacturing requirements to assure safety, purity, and stability and should be labeled in a manner that communicates essential information on product contents to the end-user.
 
On the basis of the four criteria, specific strains of microorganisms could be qualified as a probiotic for use in foods and dietary supplements with the quality, safety and functional effectiveness confirmed.

Reference:
[1] Binda, S., Colin, H., Eric, J., David, O., Bruno, P., Mary, E. S., Annie, T., Arthur, C. O. (2020). Criteria to qualify microorganisms as ‘probiotic’ in foods and dietary supplements. Front. Microbiol. 11:1400.
[2] Parker, C. T., Tindall, B. J., and Garrity, G. M. (2019). International Code of Nomenclature of Prokaryotes. Int. J. Syst. Evol. Microbiol. 69, S1–S111.
[3] ISAPP (2018). Minimum Criteria for Probiotics [Online]. Sacramento, CA: International Scientific Association for Probiotics and Prebiotics.
[4] ISAPP (2019). Probiotic Checklist: Making a Smart Selection [Online]. Sacramento, CA: International Scientific Association of Probiotics and Prebiotics.