By contributor
updated 10/22/2006 4:09:17 PM ET 2006-10-22T20:09:17

That salad of mixed vegetables you ate for lunch may not look like a scientific breakthrough. But dishes that combine a number of vegetables together may be just what the doctor ordered. Cancer researchers are finding new evidence that the many phytochemicals in plant-based foods seem to work best as a team to protect us from cancer.

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The phytochemical lycopene is a good example of how cancer prevention research is evolving. Research on this phytochemical, found in tomatoes and some other vegetables and red fruits, like watermelon, shows promise as protection against prostate cancer. Scientists also have found that lycopene from cooked tomato products such as tomato paste is more easily used by the body than lycopene from fresh tomatoes.

Now lycopene’s anti-cancer effects are being researched in combination with broccoli. John W. Erdman, Ph.D., Professor of Food Science and Human Nutrition at the University of Illinois at Urbana, decided to see if cancer protection would increase if participants ate both foods.

Lower prostate cancer
Dr. Erdman’s team fed one group of rats only broccoli powder and another group only tomato powder. Each contained all of the individual plants’ phytochemicals and nutrients. Still another group received a combination of tomato powder and broccoli powders. A final group of rats was fed a normal diet supplemented with finasteride (a drug prescribed for an enlarged prostate, a noncancerous condition).

The scientists found that the diet that combined tomato and broccoli powder resulted in much less prostate tumor growth than any of the other groups, including those receiving the drug.

Dr. Erdman is continuing to study the synergy between tomato and broccoli powders to further confirm the results of this study. “Separately, tomatoes and broccoli appear to have enormous cancer-fighting potential,” he says. “Together, they maximize the cancer-fighting effect.”

Other powerful pairings
This interactivity is likely to be taking place in any diet high in a variety of fruits, vegetables, whole grains and beans, he says.

Fruits are being studied as well for this synergistic effect. Rui Hai Liu, M.D., Ph.D., Associate Professor of Food Science at Cornell University, has examined antioxidant activity in various fruits. Although Dr. Liu found that cranberries had the strongest phytochemical activity of 11 fruits he studied, he says, “The antioxidant activity of cranberry and apple together is much higher than the separate measurements for these fruits,” he says.

Dr. Liu estimates that there are probably more than 8,000 phytochemicals in plant foods, and each one works with others to perform many protective functions. These include stimulating the immune system, warding off damage from free radicals and putting the brakes on cell growth.

So combine a wide variety of vegetables and fruits into salads or other dishes to get the most protection from cancer. 

For free recipes featuring these combinations, visit the American Institute for Cancer Research's Web site.

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