`Superfoods' for long-term health


Micronutrients: Scientists increasingly believe that certain natural chemicals in foods can combat or prevent disease.

June 11, 1999|By Mark Guidera | Mark Guidera,SUN STAFF

The humble red tomato, that ubiquitous summer obsession of many a backyard gardener, is now the obsession of food and medical researchers.

The reason: It might be a "superfood." That is to say, tomatoes, already delectable summer fare, might offer a powerful health boost as well.

The potential medicinal properties of tomatoes and other possible superfoods are exciting scientists, who are increasingly convinced that the chemicals they naturally contain could combat, or even prevent, chronic and acute conditions ranging from high cholesterol to cancer.

For example, the tomato, fruit of the gangly, water-loving nightshade, contains lycopene, a chemical that experts think might -- emphasize might -- be able to help the body's cells ward off cancer by helping repair DNA damage.

Beverly Clevidence, who heads the new phytochemical research laboratory at the U.S. Department of Agriculture in Beltsville, foresees a time when doctors and health agencies recommend that our diets contain certain amounts of specific "superfoods" each week, if not each day.

"The evidence so far is just so highly suggestive that it's hard to dismiss," says Clevidence. "There is something in fruits and vegetables that seems highly protective."

Along with tomatoes -- "the redder the better" -- the list of edibles with potential superfood status includes: broccoli and broccoli sprouts, which contain sulforaphane, a suspected anti-cancer agent; soy, which packs phytoestrogens that some studies indicate might protect against breast and prostate cancers; and anything containing carotenoids or flavenoids, such as cauliflower, carrots, sweet potatoes and oranges.

These substances -- lycopene, carotenoids, flavenoids and the rest -- are called "phytochemicals," defined as specialized compounds that plants produce for defensive purposes, such as warding off diseases, pests and other environmental stresses.

Caretenoids and flavenoids, for example, appear to act on a molecular level to help DNA in cells repair damage from pollutants and the other routine assaults of daily living.

Dr. Paul Talalay, a professor of pharmacology at the Johns Hopkins University Medical School, has devoted much of his 46-year career to looking for compounds that might protect or reverse the DNA cell damage that he believes is a precursor to cancer.

He has determined that sulforaphane, a compound found in crucifer vegetables such as broccoli and cauliflower, spurs cells to produce cancer-blocking enzymes. The biggest sulforaphane punch, Talalay says, come from broccoli sprouts, and he has co-founded a company, Brassica Protection Products LLC, to market sprouts grown from high sulforaphane-yielding seed varieties.

Talalay's research suggests a strong correlation between diet and prevention of diseases, especially cancer and chronic illnesses. And he suspects that phytochemicals act in concert with one another to trigger the production of disease-fighting enzymes and other natural protectors.

It is well-established that a powerful synergism occurs between cancer-risk factors. For example, people who smoke and are exposed to asbestos have a considerably higher chance of getting lung cancer than people exposed to either risk alone.

It stands to reason, Talalay says, that a similar synergism exists for cancer-preventive compounds. Researchers are only now embarking on figuring out is what those synergistic relationships might be. It will be no easy task. The carrot, and most other "superfoods," contain more than 100 phytochemicals.

Dr. Nilo Carter, an internist and food expert at the Center for Human Nutrition at the University of Texas Southwestern Medical Center, cautions that while phytochemicals appear to offer potential health benefits, it is too soon to say that any one nutrient has a guaranteed positive effect -- and too soon to urge people to add an extra bushel of tomatoes or pound of broccoli to their diets.

Vitamin and nutrition-supplement makers, he notes, have long touted garlic and its organic sulfurs as a remedy for ills from high blood pressure to cholesterol and cancer.

But a study published recently in the Journal of the American Medical Association found "absolutely no benefit" to garlic as a cholesterol remedy, Carter says. "We need more reliable, well-organized studies like that before claims are made about any of these micro-nutrients."

Clevidence at FDA agrees.

"The real bugaboo is how to measure what benefit there is from phytochemicals and what's really causing it," she says.

To establish a reliable way of measuring how the body absorbs and retains phytochemicals, the USDA is planning a study using kale grown with large amounts of a nonradioactive isotope, carbon-13. The researchers plan to feed the kale to human volunteers and then take blood samples to measure carbon-13 levels.

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