June 21, 2000 -- It turns out that eating an apple a day really does keep the doctor away -- but you've got to eat the peel. And no fair skipping the apple altogether in favor of megadoses of vitamins in pill form. Fruits and vegetables in their natural state are better, Cornell University researchers say.
A study published June 22 in the journal Nature offers more evidence that the health benefits of fruits and vegetables are not easily packaged as supplements sold in pharmacies and health food stores. Researchers from Cornell's Food Science and Toxicology Department in Ithaca, N.Y., found that the antioxidant properties of one fresh apple were equal to 1,500 milligrams of vitamin C.
"The pharmaceutical companies will not be happy with me, but I think the consumer gets more health benefits from eating whole fruits and vegetables," lead researcher Rui Hai Liu, MD, PhD, tells WebMD. "You get much more antioxidant activity, you get a variety of antioxidants, and you don't have to worry about toxicity."
The Cornell researchers suggest that a combination of plant chemicals, collectively known as phytochemicals, found mainly in the skin of apples, provide the bulk of the fruit's anticancer and antioxidant properties. The cooperative activity of these phytochemicals, they argue, has health benefits that are superior to those found in single compounds like vitamin C, vitamin E, and beta-carotene, which have been widely studied for their antioxidant activities.
Using colon cancer cells treated with apple extract, Liu and colleagues found that 50 milligrams of apple extracted from the skins decreased the cancer cell growth by 43%, while the same amount of extract from the flesh of the apple decreased cancer cell growth by 29%. Likewise, 50 milligrams of extract from apples with the skin on decreased liver cancer cell growth by 57%, compared to 40% for samples extracted from apples without the skin.
"There is a huge amount of scientific evidence showing that fruits and vegetables lower the risk of cancer and heart disease, but scientists have mostly been isolating single compounds like beta-carotene and vitamin C," Liu says. "Over the years, no single compound has been proven to have a protective effect by itself. An apple could have hundreds of phytochemicals. We think the combination is the important thing."