The International Scientific Association for Probiotics and Prebiotics defines “probiotics” as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” . These microorganisms, which consist mainly of bacteria but also include yeasts, are naturally present in fermented foods, may be added to other food products, and are available as dietary supplements. However, not all foods and dietary supplements labeled as “probiotics” on the market have proven health benefits.
Probiotics should not be confused with prebiotics, which are typically complex carbohydrates (such as inulin and other fructo-oligosaccharides) that microorganisms in the gastrointestinal tract use as metabolic fuel . Commercial products containing both prebiotic sugars and probiotic organisms are often called “synbiotics.” In addition, products containing dead microorganisms and those made by microorganisms (such as proteins, polysaccharides, nucleotides, and peptides) are, by definition, not probiotics.
Probiotics are identified by their specific strain, which includes the genus, the species, the subspecies (if applicable), and an alphanumeric strain designation . The seven core genera of microbial organisms most often used in probiotic products are Lactobacillus, Bifidobacterium, Saccharomyces, Streptococcus, Enterococcus, Escherichia, and Bacillus. Table 1 shows examples of the nomenclature used for several commercial strains of probiotic organisms. Link