MONDAY, Sept. 26, 2005 (HealthDay News) -- Pomegranate juice stops the growth of prostate cancer in laboratory cultures and in living mice, and may do the same thing in humans, researchers report.
It's another plus for the Mediterranean fruit, which was recently reported by Italian researchers to have protective effects against heart disease in mice, preventing the build-up of fatty deposits along their artery walls.
Still, it's a long way from these findings to proof that pomegranate juice could be used to treat or prevent human prostate cancer, said Hasan Mukhtar, a professor of cancer research at the University of Wisconsin and lead author of a study in this week's issue of the Proceedings of the National Academy of Sciences.
To start with, it's not clear what's driving pomegranate juice's anti-cancer effect, he said. Part of it appears to be due to antioxidants, compounds long known to fight cardiovascular disease.
"It is also able to make prostate cancer cells undergo apoptosis -- programmed cell death -- and the mechanism for that, we don't know," Mukhtar said.
But he plans to find out. The researcher said his team's next step is to "identify the active ingredient, establish the mechanism of action, look at them in animal models and then in humans."
Don't expect overnight results. "Maybe not in my lifetime," said Mukhtar, who conducted the research with grants from the U.S. Public Health Service.
Meanwhile, there's nothing wrong with adding pomegranate juice to the diet -- just don't expect any miracles, said Samantha Heller, a senior clinical nutritionist at New York University Medical Center.
The U.S. Department of Agriculture lists pomegranates as a good source of potassium, vitamin C and antioxidants, but that can be said of a lot of other natural foods, she noted.
"Fruits, vegetables, legumes and whole grain foods have phytochemicals that help prevent diseases like heart disease, cancer and diabetes," Heller said. "They protect cells from damage and repair cell damage. For the best cancer protection, those are the foods we should be including in our diet these days."
As to the current study, "there's nothing wrong with it, but we can't take scientific data from a Petri dish and extrapolate it to humans," she said.
And in general, "pomegranates probably won't make a significant difference in the risk of prostate cancer if other factors are not taken care of," Heller said. "We know what we need to do to be healthy."
The study was called "intriguing" by Jeffrey Blumberg, director of the Tufts University Antioxidant Research Laboratory, primarily because of the work involving mice. A number of other studies have shown that compounds in pomegranate and other fruits and vegetables have anticancer effects, but this one went on to a test with living animals, he said.
These were special mice, bred to have a weakened immune system, and they were given high doses of pomegranate extract, Blumberg stressed. But still, "this was a whole-organism study, and it works in that model. It certainly warrants additional research to follow up the finding."
Nevertheless, he said, right now, "I would not encourage every middle-aged man to eat two pomegranates a day," Blumberg said.
Find out more about antioxidants at the American Dietetic Association.