More than 900 different plant chemicals have been identified as components of different fruits, nuts, grains, and vegetables. Apples are rich in isoflavones and phenolics, but other widely studied phytochemicals include lycopene, found in tomatoes; carotenoids, found in carrots and citrus fruits; and allyl sulfides, found in garlic and onions. It is believed that various phytochemicals help prevent cell damage, prevent cancer cell replication, and decrease cholesterol levels.
Charles Halsted, MD, says evidence is mounting that suggests taking vitamin supplements, even in large doses, does not provide the health benefits of a healthy diet. Halsted edits the American Journal of Clinical Nutrition (AJCN) and is a professor of internal medicine at the University of California, Davis. He was not involved with the study, but reviewed it for WebMD.
"I think the argument that natural sources of antioxidants are better is a pretty sound one," he says, adding that AJCN will soon publish studies showing a diet high in fruits and vegetables to be protective against heart attacks and colon cancer.
"If you look at single compound studies, you see mixed results," Halsted says. "For example, the early studies of beta-carotene suggested that it protected against lung cancer, but later studies found that it increased lung cancer risk. Single supplements may not be able to provide the benefits of a healthy diet."
The Cornell study was funded, in part, by the New York Apple Research Development Program and the New York Apple Association, and Liu is an eager spokesman for their favorite fruit.
"You should eat an apple every day," he says. "Everybody in my family gets an apple a day. We go through several thousand apples a year."
- Many of the antioxidants in an apple are in the skin, which might have cancer-fighting properties.
- Researchers think it's better to get antioxidants from fruits and vegetables than from dietary supplements. These naturally occurring plant chemicals, or phytochemicals, may work together to fight cancer and other disease.
- As scientists study antioxidants, many say they are beginning to believe it's the combination of different phytochemicals working together that bring good health.