WASHINGTON — A review conducted by researchers within the Center for Food Safety and Applied Nutrition of the Food and Drug Administration has found only limited evidence linking consumption of tomatoes and a reduced risk of certain cancers.
The review, published on-line July 10 in the Journal of the National Cancer Institute, was based on the F.D.A.’s November 2005 evaluation of the scientific evidence linking tomatoes or tomato-based foods, lycopene, and reduced cancer risk. The purpose of the review was to provide some transparency to the process of evaluating claims.
The F.D.A.’s review found no credible evidence to support an association between lycopene intake and a reduced risk of prostate, lung, colorectal, gastric, breast, ovarian, endometrial or pancreatic cancer, nor did it find any credible evidence for an association between tomato consumption and a reduced risk of lung, colorectal, breast, cervical or endometrial cancer.
However, the F.D.A. did note very limited evidence to support an association between tomato consumption and reduced risks of prostate, ovarian, gastric and pancreatic cancers. Based on these findings, the F.D.A. decided to allow qualified health claims for a very limited association between tomatoes and these four cancers.
For prostate cancer, for example, the F.D.A. issued this statement: "Very limited and preliminary scientific research suggests that eating one-half to one cup of tomatoes and/or tomato sauce a week may reduce the risk of prostate cancer. The F.D.A. concludes that there is little scientific evidence supporting this claim."
As part of its review, the F.D.A. examined data from 107 observational studies comparing the level of consumption of either tomatoes or lycopene with people’s general cancer risk. They also looked at 23 studies that focused on blood levels of lycopene.
In an editorial accompanying the review, Edward Giovannucci of the Harvard School of Public Health in Boston, said the F.D.A.’s findings should not be too surprising, given the complexities of studying the relationship between tomato or lycopene intake and prostate cancer risk. However, he urged further research on the subject.
"Although it may be premature to espouse increased consumption of tomato sauce or lycopene for prostate cancer prevention, this area of research remains promising," Mr. Giovannucci said. "Studies of advanced prostate cancer conducted in populations with a wide variation in lycopene levels and in which the diagnosis of prostate cancer is not excessively influenced by (prostate-specific antigen) screening, such as in the European Prospective Investigation into Cancer and Nutrition study cohort, should prove informative."