Prune (dried plum) consumption does not reduce colonic tumor formation but drives beneficial changes in the gut microbiome of rats

Previous research has highlighted the potential benefits of prune consumption, including a changed gut microbiome composition and a reduction in colon cancer risk factors. This study investigated whether prune consumption reduced colon tumor development and led to positive changes in the large intestinal microbiome in a chemically induced colon cancer model in rats. Male Wistar rats were fed one of three diets: 5% (by energy) prune, 10% prune, or a prune-free control. Rats were fed the diets for 32 weeks. Rats received weekly injections of 1,2-dimethylhydrazine for 15 weeks to induce colon tumorigenesis. Colonic tumor number or size did not differ among the diet groups. However, there was a trend toward fewer small intestinal tumors in the 10% prune diet group (p < 0.1). Groups fed prune had heavier cecum tissue, indicating greater large intestinal fermentation. The prune diets increased taxonomic richness and altered bacterial species composition. Specifically, prune consumption was associated with increased abundance of Methanosphaera genus and taxa from the Lachnospiraceae family, such as Blautia and Coprococcus. Prune diets also increased total cecal SCFA amount, notably butyrate. However, 24 hour fecal excretion of p-cresol, indole, and total bile acids did not differ significantly among the groups. While prune consumption did not show a significant reduction in colonic tumor formation, potential benefits were noted in a trend towards reducing small intestine tumors, increasing large intestinal fermentation and SCFA production, and increasing microbial richness, suggesting prune consumption may provide other health benefits.