Fruits, vegetables and the risk of cancer: A multisite case-control study in Uruguay

Introduction: Previous studies have suggested that high intake of fruit and vegetables may decrease the risk of a wide range of cancers, but this evidence has been challenged by the results of recent studies. Methods: To further explore the association between fruit and vegetable intake and cancer risk we conducted a case-control study of 11 cancer sites in Uruguay between 1996 and 2004, including 3,539 cancer cases and 2,032 hospital controls. We used unconditional logistic regression to estimate odds ratios and 95% confidence intervals (CIs) of cancer associations. Results: In the multivariable model higher intake of fruits and vegetables combined was associated with a decreased risk of cancers of the esophagus (odds ratio, OR=0.63, 95% CI: 0.42-0.97), lung (OR=0.75, 95% CI: 0.57-0.98), breast (OR=0.47, 95% CI: 0.31-0.71), prostate (OR=0.63, 95% CI: 0.44-0.92) and all sites combined (OR=0.73, 95% CI: 0.61-0.87). When evaluated separately, fruit intake was more strongly associated with decreased cancer risk than vegetables. These inverse associations were mainly observed in men, among persons with high intake of meat, alcohol drinkers and among smokers. Conclusion: Our results provide some evidence that high intake of fruits and vegetables and particularly fruit may decrease the risk of cancer. However, because of the possibility that these findings could be due to residual confounding from intake of meat, alcohol drinking and tobacco smoking, further studies in populations with a large number of participants with low or no exposure to these potential confounding factors are warranted.