The August 1, 2008 issue of the journal Cancer Research published the finding of researchers at Ohio State University that consuming black raspberries can prevent some of the genetic changes that result from carcinogen exposure, thereby reducing the risk of cancer.
Professor of pathology and human nutrition Gary D. Stoner and his associates fed rats a normal diet or a diet that contained 5 percent freeze-dried black-raspberry powder for three weeks. “Freeze drying the berries concentrates these elements about ten times, giving us a power pack of chemoprevention agents that can influence the different signaling pathways that are deregulated in cancer,” Dr Stoner noted.
During the third week of the diet, half of the animals were injected with the carcinogen N-nitrosomethylbenzylamine, and genetic changes in the esophagus were measured. Among rats that received the carcinogen, 2,261 of 41,000 genes examined showed a 50 percent or more change in activity, yet in animals that received berry powder, 462 of these altered genes demonstrated near-normal activity. The majority of the genes affected were involved with cell proliferation and death, cell attachment and movement, new blood vessel growth and other processes related to cancer development. Animals given black raspberry powder also had healthier-appearing esophageal tissue compared with the other carcinogen-treated group.
In a companion study published Cancer Research in 2007, NMBA-treated rats that received diets supplemented with phenylethyl isothiocyanate (PEITC), a compound which occurs in cruciferous vegetables such as broccoli, were protected from changes to 1,323 genes. The current study determined that 53 of these genes were also protected by black raspberry. These include genes involved in metabolism and oxidative damage, oncogenes, and tumor suppressor genes.
“Because both berries and the second agent maintain near-normal levels of expression of these 53 genes, we believe their early deregulation may be especially important in the development of esophageal cancer,” Dr Stoner commented.
“We have clearly shown that berries, which contain a variety of anticancer compounds, have a genome-wide effect on the expression of genes involved in cancer development,” Dr Stoner stated. “This suggests to us that a mixture of preventative agents, which berries provide, may more effectively prevent cancer than a single agent that targets only one or a few genes.”
“What’s emerging from studies in cancer chemoprevention is that using single compounds alone is not enough,” he added. “And berries are not enough. We never get 100 percent tumor inhibition with berries. So we need to think about another food that we can add to them that will boost the chemopreventive activities of berries alone.”