Research presented at Experimental Biology (EB,Chicago,IL, April 22-26), continues to support dried plums/prunes’ role in health promotion and lowering the risk of chronic disease. Separate presentations focused on anti-inflammatory properties of dried plums’ polyphenolic compounds and on their protective role in an animal model of colon carcinogenesis.

Brenda J. Smith, PhD, Oklahoma State University has a long history of dried plum research beginning in the area of bone health. She has a particular interest in the role of polyphenols (plant bioactive compounds) in immune function. Her research looked at the ability of dried plums to protect these cells, which serve as a barrier to foreign substances, in normal and inflammatory conditions.

Dr. Smith commented that “recent studies have demonstrated an important connection between gut immunity and bone health. This is in part due to the way in which the immune system regulates bone metabolic processes. Previously our lab has shown that dried plum's polyphenols are responsible for at least some of the fruit's bone protective effects, which coincide with a decrease in inflammation. Because a significant proportion of polyphenols are not readily absorbed and a majority of our immune cells reside within the gastrointestinal tract, we wanted to investigate these compounds’ effects on the gut immune response.”

“Our results show that the polyphenols have anti-inflammatory and other immune modulating properties that are mediated by their effects on intestinal epithelial cells. These findings provide new insights as to how dried plums benefit bone, gut and immune health.”

Nancy D. Turner, PhD, Texas A&M University continues her research on the role of dried plums in a rat model of colon cancer. Her previous research discovered that rats fed a dried plum diet had fewer precancerous colon cancer lesions (aberrant crypt foci) than rats fed the control diet and had different distributions of colonic microbiota. Based on these findings, which were seen at levels equivalent to a 40g serving of dried plums, her team wanted to characterize the metabolome (diet-derived small molecules and microbial metabolites) in the colon of the rats.

The study analyzed and discovered numerous differences in these compounds based on the location in the colon, the diet (control or dried plum) and the interaction between the location and diet. Some of the compounds endogenous to dried plums were found in animals fed the dried plum diet but were not detected in the control animals. These included sugar alcohols (mannitol/sorbitol), sugar derived metabolites and other plant-associated compounds. Animals fed the dried plum diet also had an increase in microbially-derived metabolites suggesting that consumption of the whole fruit delivered a unique combination of dried plum bioactives to the colon. These results suggest that dried plums through their endogenous compounds or through microbially-derived metabolites change the colon environment, which may have contributed to the reduction of precancerous lesions in Dr. Turner’s initial research.

According to Dr. Turner, “some of the metabolites identified are tied to pathways directly involved in colon carcinogenesis. These data indicate dried plums/prunes are able to beneficially alter the colonic environment directly, or through their effect on the metabolism of the microbiota present there. Because of these effects, dried plums may reduce the risk of colon cancer development.”

Washburn KR, Crockett EK, Grae JL, Lucas EA, and Smith BF. “Polyphenolic compounds downregulate IL-6 in gut epithelial cells under inflammatory conditions.” The FASEB Journal April 2017. Vol. 31 No. 1 Supplement 166.6

Seidel DV, Taddeo SS, Azcarate-Peril MA, Carroll RJ, and Turner ND. “Dried plums modify the colon luminal metabolome in a rat model of colon carcinogenesis.” The FASEB Journal April 2017. Vol. 31 No. 1 Supplement 590.5.