Shared mechanisms within taxonomic groups go beyond strain-specific effects.
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Probiotic benefits may derive from mechanisms that are shared among strains.
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A shared mechanism may lead to a shared benefit exerted by most members of a taxon.
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One example of a shared mechanism is short chain fatty acid production.
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Another shared mechanism is cell surface components that enhance GI survival.
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Another shared mechanism is effector molecules which signal the immune system.
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Not all microbes expressing these mechanisms are necessarily probiotics or beneficial.
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Shared mechanisms may allow assignment of probiotic benefits to taxa beyond a strain.
Strain-specificity of probiotic effects has been a cornerstone principle of probiotic science for decades. Certainly, some important mechanisms are present in only a few probiotic strains. But scientific advances now reveal commonalities among members of certain taxonomic groups of probiotic microbes. Some clinical benefits likely derive from these shared mechanisms, suggesting that sub-species-specific, species-specific or genus-specific probiotic effects exist. Human trials are necessary to confirm specific health benefits. However, a strain that has not been tested in human efficacy trials may meet the minimum definition of the term ‘probiotic’ if it is a member of a well-studied probiotic species expressing underlying core mechanisms and it is delivered at an effective dose.
Graphical abstract
Shared probiotic mechanisms and their taxonomic distribution.
