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Fruits, Vegetables Offer Little Cancer Protection

Study Finds Protective Effect of Diet Rich in Fruits, Vegetables Modest at Best
By
WebMD Health News
Reviewed by Laura J. Martin, MD

April 6, 2010 -- Eating a diet rich in fruits and vegetables is good for many reasons, but don't expect it to offer much protection against cancer, according to a new study.

The researchers aren't saying the fruits and vegetables have no effect. "Fruits and vegetables are likely to be protective, although the effect is not likely to be large," says study author Paolo Boffetta, MD, MPH, deputy director of The Tisch Cancer Institute at Mount Sinai School of Medicine in New York.

But he hastens to add that eating plenty of fruits and vegetables is good for a number of other reasons, such as reducing the risk of cardiovascular disease. His study looked at the big picture, he tells WebMD, and so it's still possible that specific fruits and vegetables, or substances in them, could be more cancer-protective.

Fruits, Vegetables, and Cancer Risk: The Study

''In the past, there was a strong belief that fruits and vegetables were strongly protective against cancer," Boffetta says. "In the last 10 or 15 years there have been a number of studies that did not confirm this relationship."

So Boffetta and his colleagues analyzed data from the large EPIC study (European Prospective Investigation Into Cancer and Nutrition). It included more than 142,000 men and 335,000 women from 10 Western European countries, evaluated between 1992 and 2000.

The researchers looked at detailed dietary information and asked about alcohol intake, smoking, and other lifestyle habits.

After a median follow-up of nearly nine years, Boffetta's team looked at the association between fruit and vegetables and cancer risk and focused on the effect of increasing intake.

More than 30,000 participants learned they had cancer during the follow-up period.

Fruits, Vegetables, and Cancer Risk: Results

The median intake of fruits and vegetables was 335 grams a day, the equivalent of about two and a quarter apples.  "One apple or one fruit is about 150 grams," Boffetta says.

They looked at the effect of increasing intake. "The more you eat, the more protective," Boffetta tells WebMD, "but the magnitude of this effect is very weak."

For instance, he says, those who increased their intake by about 200 grams a day, or about 1.5 servings a day, had a 3% or 4% reduced risk of getting cancer.

The effect was weaker for fruits when considered alone than for vegetables, he says.

Boffetta is not certain whether the findings hold for a U.S. population, but he speculates they probably do.

It's also possible that certain substances in specific fruits or vegetables may be more protective, Boffetta says. Lycopene, a substance found in tomatoes, for instance, has been found to reduce prostate cancer risk.

"Our purpose was really to look at the big picture," he says. "It's a little diluted when you look at the big picture."

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