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United States Department of Agriculture

Agricultural Research Service

A Colorful Plate of Foods Has More Appeal Than You Think!
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Huawei Zeng. Ph.D.

Remember when your mother said "eat your vegetables and you will be healthy"? Well, she was right! Research continues to demonstrate that vegetables and fruits contain disease-fighting nutrients and other components, many of which provide color to our dinner plates.

Humans and other animals use oxygen in the air to make energy to fuel the various functions required for life. Energy formed by using oxygen is needed by our hearts to beat and pump blood to organs, by our lungs to bring in oxygen and release our waste gas into the air, by our intestines to absorb the nutrients that we obtain from food. Thus, we are aerobic creatures because of our dependence on oxygen to function. A natural and key by-product of the use of oxygen is the production of very reactive chemical products called "free radicals". These chemicals are very reactive with adjacent compounds in organs. Generally, free radicals are not a problem because we have the capacity to neutralize them. For example, exercise is a common activity in which the use of oxygen is increased five to ten times above that required to sit still. If we lack the capacity to meet the increased demand to neutralize free radicals formed during exercise, then tissue damage may occur. This condition is called oxidative stress.

When people age or get too much exposure to the sun or encounter air pollution, such as tobacco smoke, the rate of free radical formation and oxidative damage increases with some tissue damage such as sunburn or sore eyes or throat. The link between oxidative stress and susceptibility to some diseases, for example cancer and viral infection, is well documented. Oxidative stress promotes replication of viruses, such as those that cause influenza and human immunovirus (HIV), and cellular DNA mutation in cancer. It also has been linked with aging.

Many foods contain antioxidants that detoxify or neutralize free radicals. Selenium, zinc, copper, manganese, folic acid, vitamins A, C, E and B-6 are key antioxidants. Lean meat, fish, dairy products, cereals and seeds provide selenium, zinc, copper, and manganese which the body incorporates into the active site of neutralizing enzymes. Vitamins C, E and beta-carotene react directly with free radicals and eliminate them. Broccoli, cabbage and other green vegetables are rich in vitamin C. Vegetable oils, whole grains, nuts, seeds, and wheat germ are good sources of selenium and vitamin E. Carrots, sweet potatoes, pumpkin, squash, and spinach supply beta-carotene. Fresh fruits and vegetables also are vitamin-rich foods.

Eating a wide variety of vegetables and fruits in generous quantities each day is a sound strategy to boost your health! In addition to boosting your antioxidant reserves, these foods also are low in fat and high in fiber, two additional factors that are considered to reduce your cancer risk.

Last Modified: 10/23/2006
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