Cranberry Extracts May Promote Gut Health

Cranberries are associated with a range of health benefits such as reducing the incidence of urinary tract infections and helping to prevent cardiovascular and neurological diseases, these positive effects are primarily attributed to high concentrations of various polyphenolic compounds such as phenolic acids, anthocyanins, and flavonols, most notably cranberries are one of the few dietary sources containing an oligomeric flavan-3-ols called A-type proanthocyanidins. 

While research has shown the positive antioxidant effects of these molecules, research has also shown that they are poorly absorbed into the small intestine, but a significant portion reaches the colon. Thus, it is believed that polyphenols exert their health benefits through their action on the gut microbiota in the colon, directly altering its composition by inhibiting the growth of pathogenic bacteria and stimulating the growth of beneficial ones. 

This study aimed to investigate the effects of cranberry supplementation containing both polyphenols and oligosaccharides on the composition and function of gut bacteria in a clinical trial involving 39 healthy participants. The participants were provided with 109 mg of commercially available purified cranberry extract called Prebiocran™ to take for four days. Plasma and urine samples were collected from all of the participants, and 28 provided fecal samples before and after the trial which were analyzed with rRNA sequencing. 

According to the researchers, after four days supplementation promoted a significant increase in the beneficial gut bacteria called Bifidobacterium which is known to help maintain gut health, and at the same time, the levels of potentially harmful bacteria called Bacteroides decreased. Additionally, the cranberry extracts also stimulated levels of another beneficial bacteria called Akkermansia muciniphila bacterium, which plays an important role in the intestinal mucosa, helping to reduce inflammation and strengthen the intestinal barrier.

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

The researchers believe these findings may be of interest to counteract the effects of a Western-style diet, explaining that "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. 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," said Yves Desjardins who led the study and is a professor at the Faculty of Agriculture and Food Sciences."The constant inflammation that results from the presence of LPS in the body can lead to several chronic diseases, including diabetes, and cardiovascular disease," he explains.

"It's promising to see a beneficial effect after just four days," expresses Jacob Lessard-Lord with enthusiasm. Explaining that although supplementation had a beneficial effect on all of the participants, the variability of their responses requires further long-term research to identify which microbiota signatures respond best to the extracts. 

The researchers are planning follow-up studies to determine the optimal dose and duration of supplementation to maximize the benefits. In the meantime, their findings provide a reason to consume more cranberries outside of festive events because their unique prebiotic and polyphenol content helps to promote gut health.