Different berries, similar cancer-fighting effects

Garden-variety berries provide about the same cancer-fighting punch as more exotic ones, a study of rats with esophageal cancer shows. A separate study finds a potentially protective effect against breast cancer as well.

Cancer biologist Gary Stoner of Ohio State University in Columbus and his colleagues tested seven berry types against cancer of the esophagus in rats —black raspberries, red raspberries, blueberries, strawberries, noni berries, açai berries and wolfberries (also called goji berries). 

The scientists injected the animals with a carcinogenic chemical and gave some of the rats normal food, while others got similar chow containing 5 percent of one of the berries in dehydrated form.

While nearly all of the rats fed normal chow developed tumors rapidly, only about two-thirds of the berry-supplemented rats did. Overall, these rats had about half as many tumors as the others, the researchers report in the June Pharmaceutical Research. The berry-fed rats also had lower concentrations of interleukin-5 and a rat version of interleukin-8, inflammatory proteins implicated in esophageal cancer.

Earlier work by Stoner’s group found that black raspberries contain ample amounts of the two cancer-fighting compounds ellagitannin and anthocyanin. Ellagitannins also show up in nuts, pomegranates and other berries, while anthocyanins give many berries a red, purple or blue color.

But the new work shows that a berry need not have large concentrations of either compound to be a cancer fighter. For example, blueberries and açai berries are high in anthocyanins but low in ellagitannins. And wolfberries are low in both, Stoner says.

“There may be different things in different berries that are providing these [anticancer] effects,” says Ramesh C. Gupta, a cancer biologist at the University of Louisville School of Medicine in Kentucky. “It’s a good thing,” he says, since availability varies by region.

In the other study, Gupta and his colleagues induced breast cancer in female rats by implanting estrogen in the animals. Some animals received a diet comprising 2.5 percent dehydrated blueberries or black raspberries and others got food without berries. Those getting berries showed less tumor growth, the researchers report in the June Cancer Prevention Research. The berries also decreased activation of two genes implicated in breast cancer, CYP1A1 and CYP1B1.

Although the various berries tested in these studies differ from one another in chemical composition, they have things in common, such as an anti-inflammatory effect, Stoner says. They also contain cellulose, lignin and pectin. These fibrous compounds “may be the common denominator,” he says, because in digesting these fibers, the body makes butyrate, which previous research has shown may have anticancer properties.

“It could be the presence of more conventional antioxidants such as the carotenoids, or more likely vitamin C, which was not measured in this study,” says Susan Duthie, a nutritional biochemist at the University of Aberdeen in Scotland.

In any case, the potent anticancer effect of berries shown in lab-dish and animal studies has yet to be replicated in people, she cautions. A huge European study reported earlier this year found only very modest protection against cancer from a diet high in fruits and vegetables. “There is stronger protective evidence for berries and the compounds in them against heart disease and cognitive decline in humans,” Duthie says.