When UK researcher Glenn R. Gibson introduced the concept of prebiotics to the scientific community in 1995, in a landmark paper co-authored with his colleague Marcel B. Roberfroid, it was clear to him that the gut microbiota had the potential to play a major role in health. He and Roberfroid had noted that by increasing populations of bifidobacteria and lactobacilli in the gut, the microbiota would move “towards a more salutary regimen”. But when administered directly, these bacteria were mostly transient.
They proposed taking a different approach: providing the desired bacteria with the substrates they preferred in order to effect a change in microbial populations. Thus, they had come up with the concept of prebiotics: “nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacterial species already resident in the colon, and thus attempt to improve host health”.
Since then, the prebiotic concept has expanded, with different groups around the world attempting to update the definition. But it wasn’t until this year that a group of scientists from the International Scientific Association for Probiotics and Prebiotics (ISAPP) released their consensus definition of prebiotics, as published in Nature Reviews Gastroenterology & Hepatology: “a substrate that is selectively utilized by host microorganisms conferring a health benefit”.
According to Gibson, now Professor of Food Microbiology at the University of Reading (UK), the time had come to include populations of bacteria other than bifidobacteria and lactobacilli in the prebiotic definition—even though a long history of research associates bacteria from these two genera with robust health.
“We still feel that bifidobacteria and lactobacilli are the key targets,” Gibson says in an interview with GMFH editors. “However, knowledge of microbiome diversity has markedly expanded in the last few years and other possible health promoting genera are apparent. They do not have the track record of the others yet and research into their mechanisms, safety, ecology, and interactions are ongoing. Some may carry out metabolic functions that bifidobacteria and lactobacilli do not (e.g. butyrate or propionate production).”
Gibson thus sees the new definition of prebiotics not as a radically different one, but as one that continues and expands upon previous research threads.
He adds that the expanded definition takes into account possible prebiotic substances that target microbes in parts of the body outside the colon. “Other human and animal ecosystems, apart from the gut, are appropriate for prebiotic use—here the target microorganisms differ.”
With increasing evidence on how dietary manipulations of the gut microbiota are connected with health outcomes, prebiotics will likely acquire a new clinical significance in the years ahead; knowing how and when prebiotics are useful, both therapeutically and preventatively, will become important for clinicians working in nutrition and other fields of healthcare.
Gibson points out that a section of the new article covers the ability of prebiotics to “reduce the risk or burden of disease”, as demonstrated by controlled studies linking prebiotic substances with particular aspects of health.
He offers a take-home point for clinicians: “Prebiotics are safe, efficacious, and user friendly. They can also be used prophylactically [and] as an adjunct to existing therapy.”
References:
Gibson GR, Hutkins R, Sanders ME, et al. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nature Reviews Gastroenterology & Hepatology. 2017; 14: 491–502.
Gibson GR & Roberfroid MB. Dietary modulation of the human colonic microbiota: Introducing the concept of prebiotics. Journal of Nutrition. 1995; 125(6): 1401-12.
