Dried plums may help protect against colon cancer, according to new research.
The study, carried out by Dr. Nancy Turner, Texas A&M AgriLife Research professor in the nutrition and food science department of Texas A&M University, College Station, and colleagues shows that dried plums encourage retention of microbiota - also known as gut bacteria - in the colon, which could lower the risk of colon cancer.
There is already evidence that diet can change the metabolism and composition of colon microbiota. According to Dr. Turner, there are trillions of bacteria in the intestinal tract, of which more than 400 individual species have been identified.
Disruptions to the microbiota appear help trigger initial intestinal inflammation and recurrences. Recurrent inflammation can promote development of colon cancer in the long term.
Dried plums contain phenolic compounds, which have various effects on human health, such as serving as antioxidants that neutralize the oxidant effects of free radicals, which can damage DNA.
The scientists hypothesized that consuming dried plums would promote retention of beneficial microbiota and patterns of microbial metabolism in the colon, which could in turn decrease the risk of colon cancer.
Dried plums maintained levels of beneficial gut bacteria
They tested the effect of phenolic compounds on a rat model of colon cancer. The rats were fed either a diet containing dried plums or a control diet.
The diets were matched for total calories and macronutrient composition to ensure that any effect might be accurately attributed to the dried plums. The intestinal contents and tissues from different segments of the colon were examined.
The team made two important discoveries.
The dried plum diet changed the levels of the two major phyla of bacteria in the gut. In the distal colon, it increased the level of Bacteroidetes, but reduced the amount of Firmicutes. However, in the proximal colon, the proportions were not affected.
In contrast, the control diet led to a lower proportion of Bacteroidetes and increased Firmicutes in the distal colon.
The rats that consumed the dried plums had significantly reduced numbers of aberrant crypts, aberrant crypt foci and high-multiplicity aberrant crypt foci compared with control rats.
According to study Derek Seidel, a doctoral graduate student and research assistant, these aberrant crypt foci tend to be a strong indicator for cancer development, being one of the earliest observable precancerous lesions.
The results seem to suggest a positive role for dried plums in protecting against colon cancer through establishing microbiota compositions in the distal colon.
Dr. Turner says:
"From this study we were able to conclude that dried plums did, in fact, appear to promote retention of beneficial microbiota and microbial metabolism throughout the colon, which was associated with a reduced incidence of precancerous lesions."
She calls for further investigations, particularly in human studies, to find out if dried plums could provide a viable alternative option to help reduce colon cancer.
The study was funded by the California Dried Plum Board.