Dehydrated tomatoes may fight prostate tumors

By Amy Norton

NEW YORK (Reuters Health) - A compound found in dehydrated tomatoes may help quash prostate cancer tumors, new animal research suggests.

Studies have come to conflicting conclusions as to whether tomatoes or lycopene, an antioxidant found in tomatoes, might offer prostate cancer protection. One recent study found no correlation between men's blood levels of lycopene and their risk of prostate cancer.

The new findings, reported in the journal Cancer Research, suggest that the processing of the tomato may be a key factor.

Researchers found that a form of carbohydrate called FruHis, found in dehydrated tomatoes, appeared to protect rats from developing prostate tumors. The greatest protection came from dehydrated tomatoes that had been rehydrated into tomato paste and supplemented with additional FruHis.

The findings could aid in developing new, less toxic cancer therapies, said lead researcher Dr. Valeri V. Mossine, of the University of Missouri in Columbia.

Mossine and his colleagues divided rats into four groups; one group was fed a diet of normal chow, while the other three groups were given chow supplemented with tomato powder, tomato paste, or tomato paste with added FruHis.

All of the animals were treated with chemicals designed to induce prostate tumors.

Rats on the high-FruHis diet lived longer than the other three groups. What's more, the researchers found prostate tumors in only 18 percent of these animals after death, compared with 63 percent of rats given normal chow, and 43 percent and 39 percent of animals given tomato powder and standard tomato paste, respectively.

Looking at FruHis activity in the lab dish, the researchers found that it might work in two ways, Mossine told Reuters Health.

First, the compound seemed to act like an antioxidant, protecting cells' DNA from oxidative damage that can lead to cancer. Then, when combined with lycopene, FruHis was able to kill off prostate cancer cells.

So in theory, Mossine explained, FruHis may inhibit the initial development of prostate tumors and, in concert with lycopene, hinder the growth and spread of such tumors.

It's too soon, however, for men to start eating tomato paste in the hopes of thwarting prostate cancer.

"The most important next step would be conducting trials on humans," Mossine said. Further lab work, he added, could also shed light on whether there are other compounds in dried vegetables or fruits that "work along" with FruHis.

"In my opinion, this study will make the cancer research community aware of a novel type of potential antioxidant and chemopreventive agent that may arise as a result of food processing," Mossine said.

"Hopefully, it will help to attract more attention and support to the prostate cancer prevention research area."

SOURCE: Cancer Research, June 1, 2008.