Back grey_arrow_rt.gif
Fruits and Veggies Have Small Effect on Cancer Risk
Published: April 07, 2010
Loading up on fruits and vegetables led to a "very small" effect on cancer risk, according to an analysis of data on the eating habits and health of almost 500,000 people in Western Europe.
An increase in fruits and vegetable consumption of about 7 ounces a day reduced cancer risk by 3% during a median follow-up of almost nine years. A 3.5 ounce/day increase in total vegetable intake reduced cancer risk by 2%.
The findings suggest a need for more circumspection about the potential impact of fruit and vegetable intake on cancer risk, according to an article in the April 21 issue of the Journal of the National Cancer Institute.
Action Points
* Explain to patients that this study showed only a small effect on fruit and vegetable consumption on cancer risk.
* Note that the findings came from a retrospective analysis of data, not a prospective clinical trial.
* The study was conducted in Western Europe, and the applicability to North Americans is unclear.
"Our study supports the notion of a modest cancer preventive effect of high intake of fruits and vegetables, and we can exclude chance as a likely factor," Paolo Boffetta, MD, of Mount Sinai Medical Center in New York City, and colleagues wrote.
"Nevertheless, the observed association of cancer risk overall with vegetable and fruit intake was very weak, and we cannot entirely rule out the possibility of residual confounding by these or other factors," they added.
"Given the small magnitude of the observed associations, caution should be applied in interpretation of the results."
Multiple health organizations worldwide recommend consumption of five servings of fruit and vegetables daily (about 14 ounces total) to ward off heart disease, cancer, and other conditions.
However, no study has demonstrated conclusively that a high intake of fruit and vegetables reduces the risk of cancer, the authors wrote.
On the basis of data from more than dozen studies, the international Agency for Research on Cancer has classified evidence of a chemopreventive effect as limited (IARC Press, 2003).
Most studies have focused on fruit and vegetables' chemopreventive effects on specific types of cancer, the authors continued. The few studies that have examined overall cancer incidence produced mixed results.
In an effort to clarify the chemopreventive potential of fruit and vegetables, Boffetta and co-authors reviewed data from the European Prospective Investigation into Cancer and Nutrition (EPIC).
The study examined associations between diet and cancer in 10 Western European countries with widely varying intake of fruit and vegetables.
The analysis included about 480,000 adults ages 25 to 75, about two-thirds of them women. During a median follow-up of 8.7 years, 9,604 men and 21,000 women had cancer diagnoses, resulting in cancer incidence rates of 7.9 per 1,000 person-years in men and 7.1 in women.
Fruit and vegetable intake and total vegetable intake had similar associations with cancer risk across the entire cohort.
Analyzed as a continuous variable, 7 ounces daily of fruits and vegetables were associated with a cancer hazard ratio of 0.97 (95% CI 0.96 to 0.99). A 3.5 ounce per day increase in total vegetable intake yielded a hazard ratio of 0.98 (95% CI 0.97 to 0.99).
Analysis by sex showed the beneficial effect of total vegetable intake was limited to women. Total fruit intake did not have a significant impact on cancer risk.
Stratification of patients into quintiles of fruit and vegetable intake showed a significant trend toward reduced cancer risk as intake increased from 0-to-8 ounces per day at the low end to ≥ 22.4 ounces on the high end (HR 0.95 to HR 0.89, P<0.001). The effect was similar in men and women.
Similarly, cancer risk declined as total vegetable intake increased (HR 0.97 to HR 0.93, P<0.001) and as total fruit intake increased (HR 0.96 to HR 0.94, P=0.006).
Stratification of EPIC participants by alcohol intake suggested a greater impact of fruit and vegetable intake on cancer risk in heavy drinkers, but only for cancers associated with alcohol and smoking.
Primary source: Journal of the National Cancer Institute Source reference:
Boffetta P, et al "Fruit and vegetable intake and overall cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC)" J Natl Cancer Inst 2010; DOI: 10.1093/jnci/djq072.
  icon paper stack View Older Articles   Back to Top