Esophageal Cancer Rate Drops in Rats Fed Black Raspberries

NEW ORLEANS--A diet rich in black raspberries prevented chemically induced esophageal tumors in rats, Laura Ann Kresty, MS, reported at the American Association for Cancer Research annual meeting. Ms. Kresty is a PhD graduate student at Ohio State University College of Medicine and Public Health, working in the laboratory of Gary D. Stoner, PhD, professor and chair of the Environmental Health Sciences Division.

In the study, male F344 rats were fed a diet high in powdered freeze-dried black raspberries (5% or 10% of the diet) for 30 weeks. Two weeks after the start of the high-raspberry diet, rats began receiving subcutaneous injections of N-nitro-somethylbenzylamine (NMBA), a carcinogen, once a week for 15 weeks.

Ms. Kresty and her co-workers found that the percentage of rats who developed esophageal tumors dropped 21.4% with the 5% diet and 7.7% with the 10% diet. The number of tumors per rat also fell--by 38.7% in the rats on the 5% diet and 48.9% in rats on the 10% diet. Furthermore, levels of O6-methylguanine (a marker for NMBA metabolism) in esophageal DNA declined by 73% and 80%, respectively, in the rats receiving the 5% and 10% raspberry diets.

Ms. Kresty said she chose black raspberries to study because they are high in ellagic acid, a phenol found in many fruits and nuts that may have antimutagenic and anticarcinogenic properties, but, she noted, the component or components of black raspberries that inhibit tumors are as yet unknown.