Table 3: Criteria used to define a probiotic microorganism.

Safety criteriaBe of human origin
Nonpathogenic in nature
Generally recognized as safe (GRAS)

Functional criteriaBe resistant to destruction by gastric acid and bile salts
Adhere to intestinal epithelial tissue
Be able to colonize the gastrointestinal tract, even in the short term
Modulate immune responses
Produce antimicrobial substances
Influence human metabolic activities (i.e., cholesterol assimilation, lactase activity, vitamin production, etc.)

Technological criteriaBe resistant to destruction by technical processing
Be subjected to scale-up processes