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Petunia genes inserted in a tomato may mean heart-healthy food

FRIDAY, May 4 (HealthScout) -- What do you get when you cross a tomato with a petunia?

Well, you just might have a food that can stave off heart disease or cancer, new research suggests.

Using a cauliflower virus to deliver petunia genes to certain cells in tomatoes, researchers have created -- for the first time -- a tomato rich in flavonoids, which are natural plant chemicals that may protect people against heart disease and cancer.

The tomato tastes exactly the same, the researchers say. More importantly, 65 percent of the flavonoids were retained when the tomato was cooked into paste.

"The choice of the petunia gene resulted from the fact that our Dutch collaborators -- and co-authors on the paper -- had a track record in working on flavonoids in petunias, which provided ready access to the gene," says Martine Verhoeyen, a research scientist with Unilever Research in Bedford, England.

"Tomatoes already contain small amounts of flavonols in their skin, therefore we thought it would be a good idea to boost the levels of these very promising compounds."

Tomatos are already high in lycopene, a compound thought to work well in preventing prostate cancer, Verhoeyen says. But a tomato with higher levels of flavonoids could create a plant with triple the health power -- potentially lowering the risk for heart disease and cancer, she adds.

"There is indeed some evidence that flavonols may be protective against cancer," Verhoeyen says. "However, the stronger evidence is for protection against heart disease. So tomatoes with elevated level of flavonols could potentially combat both cancer, through its lycopene, and heart disease, through its flavonols, which are the biggest killers in the Western world."

Most plants have some flavonoids, says Dr. David Ringer, the scientific program director for the American Cancer Society in Atlanta, Ga. "And there has been flavonoids research going on for some time, mostly in Japan and China where there are a lot of tea drinkers." Tea is rich in flavonoids, Ringer points out.

Flavonoids have a "a variety of biological properties," he says. "People need to understand that there are over 4,000 known flavonoids. They are an important source of antioxidants, and they show fairly striking abilities and effects on metabolism, such as stimulating the production of certain enzymes important in processing compounds from our environment."

Flavonoids may have health benefits in lowering the risk of heart disease and cancer, Ringer says. "Flavonoids may be good at free-radical scavenging. Free radicals attack membranes and cause cell damage, and that damage is implicated in processes that are known to be important in heart disease and cancer."

Verhoeyen says it took more than 18 months to breed a tomato with higher flavonoid levels and two more years to complete the research, including growing further generations of plants and making and testing the tomato paste.

"We first established what the bottleneck was in the production of flavonols by the tomato fruit," Verhoeyen explains. "The bottleneck was an enzyme that is responsible for producing one of the building blocks that make up a flavonol molecule." Replacing the bottleneck with the petunia gene, "the bottleneck was resolved, and the tomato started to produce much higher levels of flavonols -- 78 times more in fact," she says.

The research is in this month's edition of Nature Medicine.

But don't rush off to the supermarket just yet, Verhoeyen says.

"We have shown that using modern biotechnology, we can dramatically elevate flavonols in tomatoes, thus increasing the potential nutritional value of this crop," she explains. "Products in the supermarket are still a long way off -- at least five years, if not longer."

"Any product, if ever developed, would have to go through very stringent regulatory and safety procedures," Verhoeyen adds. "And importantly, the consumer would also have to be comfortable with the product and the technology used, and, of course, the benefit of the potential health claims."

What To Do

For more information on flavonoids, visit the Agricultural Research Service. And for more on the health effects of tomatoes, see the California Tomato Growers Association.

And don't forget these HealthScout stories on flavonoids.

SOURCES: Interviews with Martine Verhoeyen, Ph.D., research scientist, Unilever Research, Bedford, England; David Ringer, M.D., scientific program director, American Cancer Society, Atlanta, Ga.; May, 2001 Nature Medicine
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