Substrates that are selectively utilized by host microorganisms, conferring a health benefit.

Prebiotics are commonly referred to as ‘the food that feeds your probiotics’. To an extent, this is true. Prebiotics typically refer to a class of plant compounds or fibers that support the growth of beneficial bacteria in the gut.

However, new observations about how these and other substances interact with our gut microbes, reveal a broader definition. Scientists now argue that the growth of specific microbes is less relevant—what we do care about is what these microbes are metabolizing.

The evolved, and now official, definition, published by the International Scientific Association for Probiotics and Prebiotics, refers to prebiotics as ‘substrates that are selectively utilized by host microorganisms conferring a health benefit’. In English: nutrients used by bacteria to help you thrive. This has broadened the path to introduce new classes of non-fermentable prebiotic compounds like polyphenols that are metabolized by gut bacteria into beneficial metabolites.