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Cranberry Extracts Boost the Gut Microbiome

Bowl of red cranberries.
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A glass of cranberry juice could do more good for your gut health than you realize.

In a new study, researchers from the Canadian Institute of Nutrition and Functional Foods (INAF) showed that cranberry extracts can boost the number of Bifidobacterium bacteria in a person’s gut.

As this genus of bacteria is linked with lower levels of inflammation, the researchers posit that cranberry extracts could help lower the risks of diabetes and cardiometabolic diseases.

The findings were published in npj Biofilms & Microbiomes.

In your gut, in your guuuut

Cranberries’ nutritious boons are thought to derive mainly from their polyphenolic and oligosaccharide compounds.

The research group instructed 39 healthy participants to take cranberry extract supplements twice daily for 4 days. This daily dose was equivalent to 60grams of fresh cranberries, following extraction and purification processes.

Of the 39 participants, just 28 provided the 2 required fecal samples, which were provided on the day before and day after the 4-day study period. After comparing these samples, the researchers observed that the number of Bifidobacterium substantially increased over the four days while the number of Bacteroides bacteria significantly reduced.

When present in the gut, Bifidobacteria species are known to reduce inflammation in the body. Infusions of the bacteria have even helped alleviate inflammatory bowel disease in human trials and reduce the presence of carcinogen-induced cancerous cells in mouse models.

The INAF researchers have therefore speculated that cranberry extracts could provide similar benefits.

“Normally, these bacteria are stimulated by dietary fiber consumption,” said Jacob Lessard-Lord, a postdoctoral fellow at INAF. “We observed the same effect with cranberry extract with a dose almost 20 times lower.”

Not all the effects of the cranberry extract may be beneficial, however. When present in the gut, Bacteroides bacteria are associated with lower cases of obesity, so the participants’ reduction of Bacteroides could have undocumented health detriments, although the researchers didn’t record any such significant outcomes.

As to why the cranberry extracts caused such a microbial mix-up, the INAF team surmised that the supplements’ polyphenols had an antimicrobial effect on the Bacteroides bacteria, allowing the Bifidobacterium bacteria to consume cranberry oligosaccharides and occupy its microbial niche.

The team is now interested in exploring the long-term effects of the extracts.

“It's promising to see a beneficial effect after just four days,” said Lessard-Lord.

This article is a rework of a press release issued by Université Laval. Material has been edited for length and content.


Reference: Lessard-Lord, J., Roussel, C., Lupien-Meilleur, J. et al. Short term supplementation with cranberry extract modulates gut microbiota in human and displays a bifidogenic effect. npj Biof. Microbio. 2024. doi: 10.1038/s41522-024-00493-w