In a recently published feeding trial in The Journal of Nutritional Biochemistry, scientists investigated the potential protective effect of cranberries on the gut microbiome with an animal-based diet. Consuming cranberry compounds modified the impact of an animal-based diet in study participants by restoring a healthier microbiota profile. The addition of whole cranberry powder lessened potentially carcinogenic secondary bile acids and blunted the decline in beneficial short chain fatty acids (SCFA) in the gastrointestinal (GI) tract. “Among the 20 most commonly consumed fruits in the American diet, we chose to investigate cranberries and the gut microbiome as they are among the fruits with a high total phenol content,” said study author, Dr. Oliver Chen, which further explained the importance of the investigation because the gut microbiota is a key protector for human health. “An imbalance can increase the risk for several chronic diseases, including atherosclerosis, hypertension, kidney disease and type 2 diabetes. “Identifying foods – like cranberries – that can help shape and support a healthier gut microbiome could have a remarkable impact on public health“.
An international team led by researchers from the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, conducted a randomized, double-blind, crossover study of 11 healthy subjects (7 males, 4 females) aged 25 to 54 years with normal digestive function. A control diet, comprised of meats, dairy products and simple sugars was compared to a treatment diet – the control diet plus 30 grams of freeze-dried whole cranberry powder – for two, 5-day periods with a 2-week washout in between. The animal-based diet included meats, dairy products, and simple sugars. Stool, urine, and blood samples were obtained before and after each intervention phase. As compared to the pre-control diet, control diet modified 46 taxonomic clades, including an increase in the abundance of Firmicutes and decrease in Bacteroidetes. Moreover, it increased bacteria-derived deoxycholic acid and decreased acetate and butyrate in stool. As compared to the post-intervention phase of control diet, the cranberry diet modified 9 taxonomic clades, including a decrease in the abundance of Firmicutes and increase in Bacteroidetes.
The cranberry diet showed fewer potentially negative microbiota changes than the control diet phase. No changes were found in fecal trimethylamine (a marker for aminoacid catabolism) and plasma cytokines (markers for inflammation). It appeared that adding cranberries to the control diet reduced the rise in secondary gut bile acids that have been associated with colon and GI cancer. Cranberries also lessened the drop in beneficial SCFA thought to help maintain healthy GI cells. Overall, the treatment diet suggested that cranberry constituents may help support a healthy gut microbiome. Terry Humfeld, executive director of the non-profit Cranberry Institute – an organization established for cranberry research and education – is satisfied of the results of the study, and positively commented: “On behalf of the Cranberry Institute and cranberry growers and handlers, it is exciting and rewarding to see new diverse health research about the potential benefits of cranberry consumption. Let scientists continue to dedicate their studies to exploring the inherent value of eating cranberries, so as an industry, we will proudly continue to support their efforts”.
- Edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
Scientific references
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