The National Institutes of Health recommends people eat four to six helpings of fruits and vegetables a day. Public Health professor Gary Stoner at Ohio State University  wants black raspberries to be top on your list.

He's just published a study that found rats on a berry-rich diet had fewer malignant tumors than those not on the berry regimen. "The reduction in tumor response to a carcinogen in the esophagus and the colon was between 40 and 60 percent, and the reduction in the oral cavity was about 50 percent as well," he says and adds "That is about as good as we have ever gotten with any pure compound."

Stoner says black raspberries contain vitamins, minerals and other valuable beneficial compounds known to prevent cancer in animals. "We know now that the berries influenced the metabolism of carcinogens such that the end result is less genetic damage. And they do this by slowing the growth rate of pre-malignant pre-cancerous cells, and they also stimulate these cells to die rather than [to] grow." The berries also inhibit formation of blood vessels in cancerous tumors, which retard their growth. Stoner says his research group has begun human trials with a focus on pre-cancerous lesions in the esophagus, mouth and colon sites where the compounds can be absorbed most effectively. "So [there is a raspberry] gel in the mouth, a slurry which we give three times a day to people with esophageal lesions or colon lesions. It sort of maximizes their exposure to these berry compounds."

Stoner says it is too early in the clinical trials to report any findings, however he hopes that the results will show the same protective effect found in the animal studies. The research appears in the current issue of the journal Nutrition and Cancer.