Federal regulators cleared the way for food companies to cite certain cancer benefits by tomatoes in ads and on food labels. However, it excluded tomato-based dietary supplements.

The FDA said the health claims for fresh, dried or canned tomatoes must be qualified because they are not completely proven, the Wall Street Journal reported.

The qualified claims center on the role of lycopene, the antioxidant that gives tomatoes their red color.

The agency allowed the qualified claims for only four types of cancer and required food companies to spell out just how limited the scientific evidence is.

On prostate cancer, the FDA said, "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 Food and Drug Administration endorsed only a few of the many cancer-fighting claims manufacturers wanted to use in promoting tomato-based products and dietary supplements containing the antioxidant lycopene.

Companies can now say that eating tomatoes and tomato sauce is linked with a reduced risk of gastric, ovarian, pancreatic, and prostate cancers. That is wider than the prostate cancer claim a coalition led by H.J. Heinz Co. sought.

The FDA approval also means any manufacturer, not just the original applicants to the agency, can promote the cancer-fighting abilities of tomatoes and tomato sauce.

However, the FDA rejected some of the claims that a California supplement company, American Longevity, wanted to make.

The agency's decision, which came after a nearly two-year delay, was good news for Heinz, the world's largest tomato processor. Heinz is reviewing a 27-page letter from the FDA, but many of the company's Classico brand pasta sauces appear to qualify for the prostate cancer claim, said Debbie Foster, a Heinz spokeswoman.

In a 44-page response to American Longevity, the FDA said it found "no credible evidence" linking lycopene when used as a supplement or component of food with reduced risk of nine cancers specified in the company's petition to the agency.

The supplement maker threatened to file suit, alleging infringement of its First Amendment right to commercial free speech.

"The American public is entitled to the whole truth, and we will do all we can to prevent FDA from keeping this scientific information from the American people," said Steve Wallach, the company's general manager.

Heinz said it considers the FDA action a victory, since the agency confirmed the link between eating as little as one-half cup of tomatoes per week and a lowered risk of prostate cancer.

"We're quite excited about this and the FDA's acknowledgement that tomatoes and tomato products are 'good for you,'" the Pittsburgh company said in a press release.

"It is important to note that our petition was not for ketchup, but rather tomato products."

Still, Heinz is unlikely to halt its past practice of highlighting lycopene on ketchup labels.

"Lycopene is still the most powerful antioxidant you can find in foods," said Kerr Dow, the company's vice president and chief technical officer.

However, the language the FDA proposes for the tomato health claims is complicated. For the prostate cancer claim, the agency suggests manufacturers tell consumers: "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. FDA concludes that there is little scientific evidence supporting this claim."

Marion Nestle, a New York University nutrition professor and author of "Food Politics," criticized the FDA's decision to allow the claims because she said the science supporting them is weak.

"It makes me cry. This is an agency whose job it is to protect the health of the public, and they have been forced on political grounds to approve claims that have insufficient scientific evidence," she said.

"This is about marketing pizza as a health food. Actually, it is about marketing ketchup as a health food," Nestle said.