There's very little evidence that a diet rich in tomatoes and the tomato antioxidant lycopene can keep away cancer, according to new study from the US Food and Drug Administration.

Reporting in the July 10 issue of the Journal of the American Cancer Institute, FDA experts explained in full detail the evidence -- or mostly lack of it -- behind their November 2005 statement that tomato consumption is not linked to any decrease in the risk of tumors of the prostate, ovary, stomach and pancreas.

The agency had previously found no evidence that tomatoes could decrease risks for lung, colorectal, breast, cervical or endometrial tumors, either.

The November 2005 statement contended that, "there is no credible evidence to support qualified health claims for lycopene, as a food ingredient, component or food, or as a dietary supplement, and reduced risk of any of the cancers in the petition."

The petition for approval of the new statements was submitted by a supplement maker, American Longevity.

The FDA has put the evidence behind its decision in print, reported Paul Coates, director of the office of dietary supplements at the US National Institutes of Health and the author of a related journal editorial.

The new information review "gives people some idea of what the process is," Coates indicated. That's important, he reported, because "one of the things that people are concerned about is how are these decisions arrived at. Making the process transparent and open will be helpful."

As part of its study, the FDA collected 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, although most of those trials were deemed unreliable, either because there were too many confounding factors or because most focused on cancer patients, not healthy people.

The agency also included dozens of studies comparing lycopene or tomato intake against the risk of individual cancers such as prostate, colon and breast malignancies.