ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Tuesday, March 18, 1997 TAG: 9703180008
SECTION: EXTRA PAGE: 3 EDITION: METRO
COLUMN: personal health
SOURCE: JANE BRODY
Move over carrots and make room for tomatoes. They seem destined for center stage in the war against common cancers.
Diets rich in tomatoes and tomato products have been strongly linked to a reduced risk of cancers of the prostate and digestive tract, including colon and rectal cancers, which are among the leading cancer killers of Americans.
For example, in a six-year study of 48,000 male health professionals, Dr. Edward Giovannucci and colleagues at Harvard Medical School found that consuming tomatoes, tomato sauce or pizza more than twice a week, as opposed to never, was associated with a reduced risk of prostate cancer of 21 percent to 34 percent, depending on the food.
And a study in Italy of 2,700 patients with digestive tract cancers and 2,900 comparable but healthy people linked eating lots of raw tomatoes (seven or more servings a week) to a 30 percent to 60 percent lower cancer risk, depending on the cancer.
At a one-day symposium recently in New York sponsored by the American Health Foundation and the Tomato Research Council, an industry consortium, scientists presented these and other studies as part of preliminary but highly promising evidence of the health benefits of tomatoes. But they also demonstrated that for tomatoes to confer their apparent benefits, they must be consumed with a little fat. Yes, fat, as in vegetable oil or cheese, for example, in a pasta sauce or on a pizza or even as ketchup on a burger.
Tomatoes and tomato products are rich in a little known and understood carotenoid called lycopene. Tomatoes are the only major dietary source of lycopene, one of the more than 500 carotenoids found in plants.
Lycopene is the most abundant carotenoid in human blood and tissues, with levels in the body well above those of beta carotene. Lycopene is also a much more potent antioxidant than beta carotene, and thus may be better able to protect tissues and genes from damage by the toxic compounds that harm blood vessels and nerve cells.
So far, beta carotene has been the main focus of research efforts to reduce cancer risk through plant chemicals. But when researchers tried to prevent cancer by administering daily supplements of beta carotene to healthy people, this nutrient fell flat on its face and, in two major studies, even appeared to increase the risk of cancer.
Researchers learned a bitter lesson from the beta carotene fiasco, which they promise not to repeat with lycopene. They learned that just because a diet rich in certain foods, such as fruits and vegetables, is associated with a particular health benefit does not mean that taking one or more substances from those foods, like beta carotene, will confer the same benefit.
Rather, beneficial chemicals in foods appear to work in concert, making the surest route to good health eating the whole foods, not some extract of them.
Lycopene is the chemical that makes tomatoes red.Watermelon and pink grapefruit are the only other commonly eaten foods known to have a significant amount of it, albeit far less than tomatoes.
Other red foods, like strawberries and red peppers, do not have it. Neither do green and yellow tomatoes. Pale tomatoes have less than deep red ones. Tomatoes ripened on the vine are likely to have more than those that ripen after they are picked. Processed tomato products, which are made from specially bred very red tomatoes that are usually vine-ripened, are especially rich sources of lycopene.
But, as Dr. Gary R. Beecher, a research chemist for the U.S. Department of Agriculture, pointed out, tomatoes are not just repositories of lycopene. They also are rich sources of the essential nutrients vitamin C, potassium and folic acid, as well as beta carotene, gamma-carotene, phytoene, flavonoids and other phytonutrients, all of which may be related to the health benefits of tomatoes.
Lycopene is a fat-soluble substance and, Dr. John W. Erdman of the University of Illinois in Chicago said, to be absorbed through the intestines it must be consumed with some fat.
``About 20 percent fat calories, maybe a little less, in a meal should be sufficient,'' he said. ``Drinking tomato juice by itself results in no meaningful absorption of lycopene. The lycopene and beta carotene in the juice are so insoluble in water they will go right through the digestive tract and out the other end.''
Erdman emphasized that to enhance lycopene absorption, the fat must be part of the same meal. Having a salad with tomatoes and a fat-free dressing may not result in any lycopene. ``Stick to low-fat dressings,'' he suggested, or eat the salad with other foods that contain some fat.
Cooking tomatoes also enhances their available lycopene by breaking down fibrous cell walls that inhibit its release from the raw food. Thus, lycopene from processed tomato products - sauce, salsa, paste, ketchup, soup and canned tomatoes - is likely to be better absorbed than that from raw tomatoes.
- NEW YORK TIMES SYNDICATE
LENGTH: Medium: 88 linesby CNB