August 22, 2000 ACS NewsToday
Phytochemicals in apples seem to slow the rate at which collections of cancer cells grow. Consuming these phytochemicals in the form of fresh fruit could be a better way to get the cancer protection of antioxidants than taking vitamin C supplements, according to a recent report in the journal Nature (Vol. 405, No. 6,789).
"Our results indicate that natural antioxidants from fresh fruit could be more effective than a dietary supplement," writes Marian V. Eberhardt, who published the study along with colleagues from Cornell Universitys Department of Food Sciences.
Antioxidants protect cells from DNA damage that can be caused by very unstable forms of oxygen called free radicals. Such DNA damage can be the first step in a normal cell turning cancerous. Although free radicals occur during the course of normal cellular metabolism, their formation is accelerated by exposure to radiation and cancer-causing chemicals.
Measuring antioxidant capacity
The researchers measured the antioxidant capacity of 100 grams of apple extract and found it was about the same as 1,500 milligrams of vitamin C. Because there is only about five milligrams of vitamin C in that amount of apple extract, the researchers knew the antioxidant effect must come from other phytochemicals (plant chemicals) in the extract. An average-size apple weighs about 140 grams.
When the researchers introduced their apple extract into lab dishes holding human colon cancer cells or liver cancer cells, they found it slowed their rate of reproduction markedly, and growth slowed more with each stronger concentration added to the lab dishes.
The anti-cancer effect was strongest in extracts made from unpeeled apples, which contain more phytochemicals.
The researchers believe the large amounts of antioxidant phytochemicals found in the apple extract may help to explain the cancer protection provided by a diet that includes five servings of fruits and vegetables a day.
Eat enough fruits and vegetables
But an expert with the American Cancer Society (ACS) says its too early to say which substances in apples provide the protection and that the best way to lower your risk of cancer is to eat enough fruits and vegetables.
"This is an interesting finding, and the possibility of unlocking which of these nutrients provides the chemoprotective effects is very exciting," says David Ringer, Ph.D., scientific program director for the ACS. Chemoprevention is the use of natural or lab-made substances to lower cancer risk.
"But this study wasnt designed to prove which specific nutrients in the apples protect against cancer, or how," Dr. Ringer says. "And since we dont know yet, the surest way to get that protection is to eat a wide variety of fruits and vegetables every day, and at least five servings a day. We know that from very large dietary studies that have been done."
Still, the study provides useful information, he says. "This study shows that a food that is very available provides antioxidant protection against cancer," he says. "And it points to useful directions for future research. Its information were glad to have."
The ACS estimates that about one-third of all cancers could be prevented by eating a healthy diet and getting enough physical activity. For more information on how a healthy diet can lower your risk of cancer, go to this section of our Web site.
Copyright 2000 ACS News Today. The American Cancer Society. All rights reserved.
