Cranberries in wooden bowl

Cranberries (© nadin333 - stock.adobe.com)

QUEBEC CITY, Quebec — A popular Thanksgiving ingredient may also help cultivate a healthier gut — cranberries! A new study has found that consuming cranberry extract for just four days can significantly increase levels of beneficial gut bacteria while reducing harmful ones.

The research, led by scientists at Laval University in Canada and published in the journal npj Biofilms and Microbiomes, focused on a commercially available cranberry extract called Prebiocran. This purified extract is rich in beneficial compounds called polyphenols as well as special fibers known as oligosaccharides.

To see how the extract impacts gut bacteria, the researchers gave it to 28 healthy volunteers for four days. Stool samples were collected before and after the supplementation period to analyze the composition of the participants’ gut microbiomes.

After just four days, the cranberry extract caused a bloom in a type of good bacteria called bifidobacteria, which are known as beneficial “probiotic” microbes that help maintain a healthy gut. At the same time, levels of a potentially harmful group of bacteria called bacteroides decreased. Researchers say this can help counter the harmful effects of the Western diet.

“This diet alters the microbiota, causes inflammation of the mucosa, and compromises the integrity of the intestinal barrier, which plays a crucial role in protecting the body from bacteria present in the gut,” says study author Yves Desjardins, professor at Laval University, in a media release. “Alteration of the intestinal barrier allows the passage of lipopolysaccharides (LPS) derived from the intestinal microbiota, known as metabolic endotoxemia, and is a crucial factor in the onset and progression of inflammation and metabolic diseases.

“The constant inflammation that results from the presence of LPS in the body can lead to several chronic diseases, including diabetes, and cardiovascular disease.”

Cranberry extracts could boost microbiota and counter cardiometabolic diseases
Researchers have found that cranberry extracts could boost microbiota and counter cardiometabolic diseases. (credit: Yves Dejardins)

Bifidobacteria are adept at breaking down and fermenting the special oligosaccharide fibers found in the cranberry extract. As they feast on these prebiotic fibers, the bifidobacteria multiply and crowd out less desirable bugs like Bacteroides. Researchers believe the polyphenol compounds in cranberry, which have antimicrobial properties, also help to selectively kill off unwanted bacteria.

The cranberry extract also boosted populations of bacteria that produce butyrate, a short-chain fatty acid with potent anti-inflammatory effects. Butyrate acts as fuel for the cells lining the colon, helping to maintain a healthy gut barrier. Higher levels of butyrate-producing bacteria are associated with lower risks of inflammatory bowel diseases and even certain cancers.

When scientists analyzed blood and fecal samples, they found that butyrate concentrations tended to rise after the four-day cranberry intervention, while levels of acetate, another short-chain fatty acid, declined. The drop in acetate may be a consequence of cross-feeding interactions, wherein the bifidobacteria produce acetate that is then gobbled up by butyrate-producing bacteria.

The magnitude of the effects on the microbiome varied somewhat from person to person. Researchers were able to categorize the participants into two groups, or “enterotypes,” based on their gut bacterial patterns before and after cranberry supplementation.

Those who started out with greater numbers of Prevotella bacteria — a signature of the “enterotype 1” group — showed a much larger post-cranberry surge in a butyrate producer called Faecalibacterium prausnitzii. This obligate anaerobe is one of the most abundant bacteria in the guts of healthy adults and has been proposed as a “sensor of human health.” On the other hand, the “enterotype 2” participants, who had higher baseline levels of Bacteroides, did not experience an uptick in F. prausnitzii populations.

The fact that this short-term cranberry intervention improved gut health, particularly in enterotype 1 individuals, is quite remarkable. Whether these positive changes in the microbiome persist over a longer period remains to be seen. The researchers are planning follow-up studies to determine the optimal dose and duration of cranberry supplementation to maximize the gut benefits.

In the meantime, this research provides yet another reason to embrace cranberries — and not just on Thanksgiving. The unique prebiotic and polyphenol content of these tart red berries may make them a powerful tool for optimizing the gut microbiome. So go ahead and grab a handful of dried cranberries, sip on some unsweetened cranberry juice, or even pop a cranberry extract supplement. Your gut bugs will thank you.

StudyFinds’ Matt Higgins contributed to this report.

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