The small clinical trial also showed that the abundance of several butyrate-producing bacteria, such as Clostridium and Anaerobutyricum, increased when healthy adults consumed the branded Prebiocran extract provided by Symrise (Diana Food Canada Inc.).
“To our knowledge, this is the first study to demonstrate the effect of a short-term supplementation with cranberry extract, containing both (poly)phenols and oligosaccharides, on the fecal microbiota of human subjects,” wrote the researchers, led by Prof Yves Desjardins, PhD, from the Institute of Nutrition and Functional Foods (INAF), at Laval University in Quebec.
“Interestingly, the consumption of the cranberry extract successfully modulated the fecal microbiota of the participants included in this study with a strong bifidogenic effect. This effect is commonly associated with supplementation of prebiotic fibers, such as inulin and fructooligosaccharides.”
Cranberries
The health benefits of cranberry (Vaccinium macrocarpon) are most associated with urinary tract health, linked to the berry’s content of A-type proanthocyanidins (PACs), which are a type of oligomeric flavan-3-ols. It is known that less than 10% of these polyphenols are absorbed in the small intestine, and over 90% of these compounds reach the large intestine, where they could be fermented by microorganisms in the gut.
In addition to polyphenols, about 20% of the total extract mass of some commercial cranberry extracts are oligosaccharides, which may also exert a prebiotic effect in the host.
The new study set out to fully characterize the Prebiocran extract, and found that the majority of the oligosaccharides present were arabinoxyloglucans. The researchers also confirmed that A-type PACs were the most abundant polyphenol class in the extract.
“The combined action of (poly)phenols and oligosaccharides likely contributes to the overall impact of cranberry extract on the gut microbiota,” they wrote in npj Biofilms & Microbiomes.
Human intervention study
The potential prebiotic activity of the extract was then investigated in a clinical trial involving 28 healthy adults who were asked to consume one capsule of the cranberry extract in the morning and another in the evening for four days. The daily dose of polyphenols was 109 mg and the daily oligosaccharide dose was 125 mg.
“The daily dose given to patients, comprising two capsules, is equivalent to the extract obtained from 60 g of fresh cranberries, following extraction and purification processes,” explained Prof Desjardins and his co-workers.
The data revealed that a bifidogenic effect was observed after just four days, with significant increases noted for two Bifidobacterium species—B. adolescentis and B. longum—known to be xylo- and arabinoxylan-oligosaccharides degraders.
Increases in other producers of the short chain fatty acid butyrate were also recorded, as were measures of butyrate, but these increases did not reach statistical significance, the study noted.
“Hence, cranberry extract is a potential prebiotic, as defined by the International Scientific Association for Probiotics and Prebiotics (ISAPP), by stimulating Bifidobacterium, a beneficial bacterial genus, and Bifidobacterium appears to use oligosaccharides from the cranberry extract to favor the production of butyrate, a beneficial metabolite for the gastrointestinal health of the host, by cross-feeding with butyrogenic bacteria,” the researchers wrote.
Source: npj Biofilms & Microbiomes
2024, 10, 18, doi: 10.1038/s41522-024-00493-w
“Short term supplementation with cranberry extract modulates gut microbiota in human and displays a bifidogenic effect”
Authors: J. Lessard-Lord et al.