Healthy Colors in Fruits & Vegetables
~ September 2000 No. 109 ~
It is no surprising news that our mother´s admonishment to eat all our vegetables was good and wise advice. Did we listen? Why did some of us develop temporary "hearing" problems and slipped our broccoli to the dog? Alas, we could not have imagined then just how right she was.
There´s firm evidence that a high intake of fruits and vegetables reduces risk of cancer and heart disease. But the U.S. Department of Agriculture (USDA) Human Nutrition Center on Aging at Tufts University, Boston, Mass., is also doing studies that suggest their consumption can also stave off diminished brain function associated with aging.
Diseases related to the aging process result from the cumulative damage to cells by free radicals. Free radicals are oxygen molecules whose purpose it is to burn harmful bacteria and other refuse matter.
But, over time, their zeal wears the cell out. Because free radicals lose an electron, they become highly reactive and unstable as they search out substitute electrons from surrounding molecules. This activity is what eventually causes problems and can, to a degree, determine whether we´ll be healthy or not in what the French elegantly term Le Troiseme Age (The Third Age).
USDA scientist, Guohua Cao and Ronald L. Prior, developed the Oxygen Radical Absorbance Capacity (ORAC); a method designed to measure the ability of foods, blood plasma, and just about any substance, to subdue oxygen free radicals.
OK, so if free radicals are the culprits and antioxidants such as vitamin E are the rescuers, all we need is a vitamin pill and we´re set, right? Not according to the latest research. USDA scientists are demonstrating through nutritional research with humans and animals that increasing your intake of fruits and vegetables with high ORAC factors is more effective.
Barbara Shukit-Hale, a behavioral psychologist at the Boston center, explains she had a control group on vitamin E, one on nothing, and one on extracts from blueberries, strawberries and spinach. "In most cases," she says, "the fruit and vegetable extract group showed oxidative damage was reduced over the other control groups".
If eating our spinach is all it takes, why don´t we? "I guess because we´re a pill poping culture," says Shukit-Hale. She also points out that herbal medicines have their limitations. "Herbal medicines are not regulated by the Food and Drug Administration," she points out.
Cao found in earlier studies that vitamins C and E can, in the presence of transition metals B such as copper or iron ions B become oxidizing agents themselves. "That did not happen when the whole fruit or vegetable extract was pitted against copper ions," says Cao.
It was found that the antioxidant power in fruits and vegetables might come from more than just its vitamin content. ORAC values are higher in dark colored fruits and vegetables than lighter colored ones suggesting that color may contain essential beneficial compounds. For example, ORAC values are higher in kale than potatoes and higher in blueberries than bananas.
Cao and Prior did a study using 36 men and women ranging in age from 20 to 80. The participants doubled their intake of fruits and vegetables from 5 servings to 10 servings. Before the study, the participants averaged 1,670 ORAC units daily. Increasing the amount raised the ORAC intake to between 3,300 and 3,500 units. Cao and Prior suggest that daily intake be increased to between 3,000 and 5,000 ORAC units to have a significant impact on plasma and tissue antioxidant capacity.
|Plums:||949||Red bell pepper:||710|
|data expressed as ORAC units per 1200 g portion of food|
Franca Hernandez is a freelance writer in Salem, Oregon.