Researchers find small inverse relationship between intake of fruits, vegetables and cancer risk

An analysis by Mount Sinai researchers of over eight years of dietary data from more than 400,000 people has found that the relationship between high consumption of fruits and vegetables and a reduced risk of cancer is not as strong as commonly thought. The study is published online April 6, 2010 in the Journal of the National Cancer Institute.

It is widely believed that a diet rich in fruits and vegetables can reduce the risk of cancer. In 1990, the World Health Organization recommended eating five servings of fruits and vegetables a day to prevent cancer and other diseases. However, although many studies have been conducted since then, none have been able to confirm an association between fruit and vegetable intake and cancer resistance.

Paolo Boffetta, MD, MPH, lead author of the study and Deputy Director of The Tisch Cancer Institute at Mount Sinai School of Medicine, and colleagues analyzed data from the European Prospective Investigation into Cancer and Nutrition (EPIC) study to assess relationships between cancer risk and intake of total fruits, total vegetables, and total fruits and vegetables combined.

The EPIC cohort, which is ongoing and coordinated by professor Elio Riboli at Imperial College in London, included 142,605 men and 335,873 women recruited between 1992 and 2000 from 10 Western European countries. Detailed information on their dietary habits and lifestyle variables was obtained. After a median follow-up of 8.7 years, more than 30,000 of the study's participants were diagnosed with cancer.

Dr. Boffetta and colleagues found a small but significant inverse relationship between high intake of fruits and vegetables and overall cancer risk. In this population, an increase of 200 grams a day of fruits and vegetables resulted in a reduction of about 3 percent of cancer risk. Vegetable consumption by itself also afforded a modest benefit but was restricted to women. Heavy drinkers who ate many fruits and vegetables had a somewhat reduced risk, but only for cancers caused by smoking and alcohol.

"The bottom line here is that, yes, we did find a protective effect of fruit and vegetable intake against cancer, but it is a smaller connection than previously thought," said Dr. Boffetta. "Any cancer protective effect of these foods is likely to be modest, at best.

"However, eating fruits and vegetables is beneficial for health in general and the results of this study do not justify changing current recommendations aiming at increasing intake of these foods," said Dr. Boffetta.