To be good, does a probiotic need to be isolated from a human?
Researchers have hypothesized that a probiotic isolated from a human has properties that make it better able to function in a human. This is still a topic being researched. We do know that (1) bacteria that are native to one person are foreign to another, and (2) probiotics, even ones isolated from humans, do not seem to colonize long term. We also know that there are several probiotic strains that were not isolated from humans that have been shown to have health benefits (such as strains of Bifidobacterium animalis subsp. lactis). So more important than source of isolation of the probiotic is if clinical studies have shown it to be effective when it is administered.
