Apr. 19, 2002
     General Cancer

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Cooking red tomatoes boosts disease-fighting power

ITHACA, N.Y. -- April 19, 2002 (Cancer Digest) -- Cooking tomatoes for spaghetti or pizza sauce actually makes them healthier and boosts their cancer-fighting ability say nutrition researchers.

Despite a loss of vitamin C during the cooking process, Cornell University food scientists have found that cooking tomatoes substantially raises the levels of beneficial compounds called phytochemicals, which are powerful antioxidants that can rid the body of harmful free radicals that have been linked to cancer and other diseases.

Writing in the April 17 issue of the Journal of Agriculture and Food Chemistry, Dr. Rui Hai Liu, Cornell assistant professor of food science, says the findings run counter to the popular belief that cooking diminishes the nutritional benefits of some foods.

"This research demonstrated that heat processing actually enhanced the nutritional value of tomatoes by increasing the lycopene content that can be absorbed by the body, and boosts the total antioxidant activity. The research dispels the popular notion that processed fruits and vegetables have lower nutritional value than fresh produce," Liu said in a press release.

Liu's research team heated tomato samples to 88 degrees Celsius (190.4 degrees F) for two minutes, 15, minutes, and 30 minutes. Consistent with previous studies, vitamin C content decreased by 10 percent after two minutes of cooking, 15 percent after 15 minutes and 29 percent after cooking 30 minutes, when compared to raw, uncooked tomatoes.

The research revealed however, that the beneficial trans-lycopene content of the cooked tomatoes increased by 54 percent in the first two minutes of cooking, 171 percent after 15 minutes and 164 percent after 30 minutes of cooking. Levels of cis -lycopene (which the body easily absorbs) rose by 6 percent after two minutes of cooking, 17 percent after 15 minutes and 35 percent after 30 minutes of cooking.

The antioxidant levels in the heated tomatoes increased by 28 percent, 34 percent and 62 percent, respectively. Antioxidants protect the human body from cell and tissue damage, which occurs when harmful molecules called free radicals, released as oxygen, are metabolized by the body.

Lycopene, a carotenoid responsible for the red color in tomatoes and other fruits, has long been known as a powerful antioxidant that decreases cancer and heart-disease risk. Carotenoids, along with phenolic acids and flavonoids, are all phytochemicals, the nutritionally beneficial active compounds found in every fruit and vegetable.

.Lycopene is the most efficient single oxygen quencher, and devours more than 10 times more oxygenated free radicals than vitamin E. "This makes lycopene's presence in the diet important," says Liu.