Black raspberries have been the focus of ongoing research by Ohio State University's (OSU) Gary Stoner, PhD. It would be hard to find a juicier subject.

The blue-black berries, called "Blackcaps," only weigh about 2.0g. Despite their size, they have a high concentration of antioxidants, and have been shown in lab studies to have anti-cancer effects.

Stoner, director of the cancer chemoprevention and etiology lab at OSU, chose to study black raspberries after a series of tests of different fruits showed the berries had the highest amount of ellagic acid.

Ellagic acid is an antioxidant. It stimulates activities of enzymes that detoxify carcinogens. In lab tests in animals, it was shown to have protective effects against esophageal cancer.

The berries are also high in anthocyanins, which give them their color, and they've been shown to have anti-inflammatory properties. Some cancers, such as esophageal, have been linked to chronic inflammation.

Early tests showed that large daily doses of black raspberries inhibited esophageal and colon cancer in animals.

"We do believe that they protect the esophagus and the colon because they are absorbed by these organs as the food moves through the digestive tract,” he said in an article in "Progressline Extra," a weekly newsletter for the staff of The Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute at Ohio State University.

"Black raspberries are loaded with nutrients and [plant chemicals] that may prevent the development of cancer," he said.

While Stoner and other researchers said the berries' preventive effects cannot be solely linked to ellagic acid, they are trying to find other compounds that fight cancer.

"One or more additional berry components are undoubtedly contributing to the fruit's anti-cancer effects," he said.

Stoner has found similar anti-cancer properties in strawberries and other berries, but the black raspberry remains outstanding.

"The fact that colon cancer is the second leading cause of cancer-related mortality worldwide underscores the importance of this research," said Keith Harris, an OSU PhD candidate, also in "Progressline Extra." Harris and Stoner worked together on a study that looked at black raspberries' effects on colon cancer in rodents.

"The results [of that study] are exciting because they emphasize the influence of diet on colon cancer risk and are a first step toward examining the effects of a single food (black raspberries) on human colon cancer," he said.

But they are only a first step. Much more research is needed to prove this link in humans before any recommendations can be made. In the meantime, the best advice is for people to consume at least five servings of fruits and vegetables each day as part of a balanced diet, according to the American Cancer Society.

And here's the final delicious twist — some of this research has led to the creation of the American Berry Cooperative in Ohio, according to "Progressline Extra." The cooperative will try to expand the state's berry industry — on land formerly used to grow tobacco.