Here’s a quick round of word association: I say “prebiotic” and you think…“Fiber,” right? If that was your choice, you’re not alone. Nor are you without reason: In 2006, FDA guidance1 not only reinforced the prevailing definition of prebiotics as “nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon”—that is, “fiber”—but singled out oligosaccharides as “commonly used” prebiotics, to boot. So it’s not surprising that when most of us think about what feeds our friendly intestinal flora, we think of fiber.
Now, however, emerging research suggests that this definition may in fact be too narrow. In short, it’s possible that some probiotic bacteria may receive aid and comfort from compounds that don’t fall under the historically fibrous prebiotic rubric. Case in point: polyphenols, which “are being recognized for their prebiotic potential in addition to their wider range of health benefits,” says Shaheen Majeed, president worldwide, Sabinsa (East Windsor, NJ).
Though evidence for polyphenols’ prebiotic potential remains nascent, the possibility it holds for synbiotic formulation deserves attention. So those in the know are keeping their eyes on polyphenols and the prebiotic science surrounding them. As Majeed says, “These effects are real, and polyphenols are here to make a difference in the prebiotic category.”
It’s not as if polyphenols didn’t already deserve our love. These naturally occurring antioxidant phytochemicals—more than 8,000 of which have been identified in sources ranging from fruits and vegetables to tea, wine, chocolate, and olive oil—are the second-most abundant compounds in plants, trailing only carbohydrates.
As a class, they comprise stilbenes, lignans, phenolic acids, and flavonoids, and they exist, more or less, to protect their plant parents. But over the years, says Majeed, “research has suggested that polyphenols play a vital role in promoting our vitality and optimal health and wellness,” too, along with those of plants.
According to researchers, polyphenols’ bill of human health particulars runs from cardiovascular benefits, possible cancer prevention, and metabolic and blood sugar balance, to cognitive support, joint and bone health, weight management, a healthy inflammatory response, and—new to the list—optimal gut health.
That’s a change of pace, as gut health had primarily been the province of probiotic bacteria and the prebiotic fibers that feed them. And that makes sense, because a preponderance of evidence affirms that probiotic bacteria are instrumental to a well-functioning gastrointestinal tract, and that prebiotic fiber encourages their proliferation.
“These bacteria are important as they may have several beneficial effects on the host, especially in terms of improving digestion and the effectiveness and intrinsic strength of the immune system,” says Stephen Lukawski, BA, MEd, global sales and marketing consultant, product development and partner, Fruit d’Or Nutraceuticals (Villeroy, QC, Canada). “Preliminary research has also demonstrated potential effects of probiotic bacteria on the absorption of calcium and other minerals, bowel acidity, and inflammatory bowel disease.”
As for the fibers that fuel them, those with the highest profiles as prebiotics include inulin, fructooligosaccharides (FOS), guar gum, and resistant starch. And the high profile these specific prebiotic ingredients enjoy, Majeed notes, is thanks in no small part to the “leverage given by FDA” in its aforementioned 2006 guidance on what a prebiotic is.
New Compound on the Block
“However,” Majeed continues, “over the years, newer ingredients have caught the attention of the industry, owing to their prebiotic benefits.” In fact, the International Scientific Association for Probiotics and Prebiotics in 2016 updated its definition and scope of prebiotics to encompass non-carbohydrate ingredients, Majeed notes.
And that’s where polyphenols come in. “Several studies have demonstrated that polyphenols play an important role in improving gut health by boosting the growth of beneficial bacteria in the intestine,” Majeed says. And whereas poor absorbability is often a drawback for a nutritional ingredient, the poor absorbability of polyphenols “becomes an advantage, as far their prebiotic positioning is concerned,” Majeed adds.
So how do polyphenols perform prebiotically? Their effectiveness, Majeed says, “is suggested to be due to their ability to stimulate the growth of beneficial microbiota while inhibiting that of pathogenic strains, and to their anti-adhesion activity against harmful pathogens. Overall, they’re believed to confer positive benefits by modulating gut microecology.”
Here Comes Cranberry
And while researchers have focused mainly on the flavone, flavonol, anthocyanidin, and catechin polyphenols found in fruits, vegetables, red wine, and green tea, Lukawski says it’s time for these compounds to “move over, as here comes cranberry, and it’s showing prebiotic benefits in the gut.”
- FDA Draft Guidance. “Guidance for Industry on Complementary and Alternative Medicine Products and Their Regulation by the Food and Drug Administration.” www.fda.gov/downloads/RegulatoryInformation/Guidances/UCM145405.pdf. December 2006.
- Majeed M et al., “Cranberry seed fibre: a promising prebiotic fibre and its fermentation by the probiotic Bacillus coagulans MTCC 5856,” International Journal of Food Science and Technology. Published online February 17, 2018.