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 ime to adjust an old adage: It's the phytochemicals
in the apple each day that keep the doctor away.
 A combination
of plant chemicals, such as flavanoids and polyphenols - collectively
known as phytochemicals found both within the flesh of apple
and particularly in the skin provide the fruit's antioxidant
and anticancer benefits, say Cornell food scientists.
Their laboratory
study, funded by the New York Apple Research Development Program
and New York Apple Association, is published in the June 22 issue
of the journal Nature.
Although it
has long been known that apples provide antioxidant and health
benefits, "this concept is different," says Rui Hai
Liu, Cornell assistant professor of food science and lead author
on the Nature article, "Antioxidant activity of fresh apples."
Says Liu:
"Scientists are interested in isolating single compounds
- such as vitamin C, vitamin E and beta carotene to see if they
exhibit antioxidant or anticancer benefits. It turns out that
none of those works alone to reduce cancer. It's the combination
of flavonoids and polyphenols doing the work."
An antioxidant
is one of many chemicals that reduce or prevent oxidation, thus
preventing cell and tissue damage from free radicals in the body.
"In this
research, we have shown the importance of phytochemicals to human
health," says Liu's collaborator, Chang Yong Lee, Cornell
professor of food science at the university's New York State
Agricultural Experiment Station in Geneva, N.Y. "Some of
the phytochemicals are known to be antiallergenic, some are anti-carcinogenic,
antiinflammatory, antiviral, anti-proliferative. Now I have a
reason to say 'an apple a day keeps the doctor away.'"
Marian V.
Eberhardt, a graduate student in food chemistry who works in
Liu's laboratory, also was part of the research team.
The researchers
found that vitamin C in apples is only responsible for a small
portion of the antioxidant activity. Instead, almost all of this
activity in apples is from phytochemicals. Indeed, previous studies
have shown that a 500 milligram vitamin C pill might act as a
pro-oxidant. The Cornell researchers found that eating 100 grams
of fresh apple with skins provided the total antioxidant activity
equal to 1,500 milligrams of vitamin C.
"Eating
fruits and vegetables is better than taking a vitamin pill,"
says Liu. "You can obtain enough antioxidants from food
without worrying about toxicity. What this study shows is the
combination of phyto-chemicals plays a very important role in
antioxidant and anticancer activity, and the real health benefits
may come from a phytochemical mixture."
The researchers
used red delicious apples grown in New York State to provide
the extracts to study the effects of phyto-chemicals. The researchers
compared the anticancer and antioxidant activity in the apple
flesh, and they also studied the fruit's skin.
Using colon
cancer cells treated with apple extract, the scientists found
that cell proliferation was inhibited. Colon cancer cells treated
with 50 milligrams of apple extract (from the skins) were inhibited
by 43 percent. The apple flesh extract inhibited the colon cancer
cells by 29 percent.
The researchers
also tested the apple extract against human liver cancer cells.
At 50 milligrams, the extract derived from the apple with the
skin on inhibited those cancer cells by 57 percent, and the apple
extract derived from the fruit's fleshy part inhibited cancer
cells by 40 percent.
"The
consumption of whole fruits may provide the balanced antioxidants
needed to quench reactive oxygen species," write the researchers
in the Nature article. "Phytochemicals other than
ascorbic acid (vitamin C) ... contribute significantly to the
antioxidant activity of apples and to the capacity to inhibit
tumor cell proliferation."
Lee began
studying the enzymatic browning action of apples about 15 years
ago, identifying a variety of phenolic compounds and learning
how these chemicals work during the apple's browning action.
Liu and Lee are working to study the antioxidant activity of
various fruits and vegetables. The researchers learned that the
amount of phenolic compounds in the apple flesh and in the skin
varied from year to year, season to season and from growing region
to growing region. 
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