ABSTRACT
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Probiotics are organisms that provide health bene ts as opposed to the pathogens invading gut mucosa. Probiotics have been derived from a wide range of sources including the commensal microbiota of a particular soldier in the World War I trenches, who proved resistant to dysentery (Escherichia coli Nissle 1917), neonatal stool (Bifi dobacterium infantis), and starter cultures for yoghurt (Bifi dobacterium longum). Typically, 1 × 1010 organisms are given daily with the idea of signi cantly changing the gut microbiota. An important safety feature is that all probiotics have a short lifespan within the gut and need recurrent dosing to achieve a constant level. Studies measuring fecal probiotics indicated that fecal probiotic microorganisms disappear from the feces after 1 week of cessation of oral intake [1,2]. Prebiotics are an alternative strategy for altering the gut microbiota by providing regular doses of a speci c substrate engineered to be readily metabolized by speci c desirable
bacteria, thereby encouraging their growth. Combinations of prebiotics and probiotics are called “synbiotics.”
