Probiota 2017 saw a huge range of talks and presentations from leading minds in business and academia. Speaking at the opening session of Probiota in Berlin, Professor Bob Rastall gave details of a new debate surrounding the definition of prebiotics.
The University of Reading expert noted that the last decade has seen a surge in the understanding of what a prebiotic is, and can do, in terms of it's effects on human health. This, he said, has resulted in a growing debate over what a prebiotic actually is, and does. Part of this debate revolves around the use of 'selective fermentation' as a definition of what a probiotic is - but debates extend to asking whether nutrients such as polyphenols should generally be accepted prebiotics, and whether prebiotic effects should be restricted to the gut ecosystems.
He suggested that work in prebiotics needs to focus more on selective fermentation, and less on changes to levels of Bifidobacteria - adding that data has also shown prebiotics can have direct effects on physiology that are not mediated by gut bacteria.
“What we can start to do is think about selectivity in terms of metabolites,” said Rastall. “We can think of a path through the ecosystem from certain inputs (…) and we can have direct or indirect production of short chain fatty acids.”
“These short chain fatty acids, we are beginning to learn, have a variety of systemic effects.”
He added that many of the calls to change the definition of what a prebiotic is are generally coming from the industry, "that clearly would like to sell various things as prebiotics, which don't fit the current definition."
However, he told NutraIngredients that as a scientist he likes the current definition, which focuses on mechanisms.
"The latest definition that has scientific credibility really is the ISAPP definition from 2010, and at the ISAPP meeting in Canada where we came up with that definition we discussed at great length the application of the prebiotic concept to other ecosystems," said Rastall - noting that the while the definition specified a dietary prebiotic and references the gastrointestinal system, it was designed to encourage people to switch out the words 'dietary' and 'gastrointestinal' with other appropriate options.