By Eileen Ackerman
RD, Clinical Dietitian, Scripps Memorial Hospital Encinitas
Antioxidants, beta-carotene, vitamin C. All mainstream buzzwords and nutritional components that protect body cells from damage caused by the oxidative effects of free radicals. Free radicals are atoms or groups of atoms with an odd number of electrons. They form when oxygen interacts with certain molecules.
Once formed, these reactive elements can start a chain reaction that can domino into a dangerous reaction with important cellular components such as DNA, or cell membranes. When this happens, cells function poorly or die. To counter these harsh effects, the body has a defense system of antioxidants.
Antioxidants are molecules that interact with free radicals and end their reaction. Although there are several enzyme systems within the body that forage free radicals, the principle micronutrient (vitamin) antioxidants are vitamin E, beta-carotene, and vitamin C. Because the body cannot manufacture these micronutrients, they must come in the form of those supplied by a healthy diet.
We have all heard the statement, “eat your fruits and vegetables,” and there is good reason for it. Fruits, vegetables and whole grains have the potential to delay the onset of many age-related diseases. That’s where antioxidants come into play. Some of the smallest fruits, like the pomegranate seed, have a high concentration of antioxidants in the form of key vitamins and minerals, protein and fiber. Other larger fruits — such as local favorite the avocado — have about the same amount of protein and fiber but a third more potassium and iron, and a little less selenium.
Antioxidants are present in foods as vitamins, minerals, carotenoids, and polyphenols, among others. According to the Unites States Department of Agriculture, many antioxidants are identified in food by their distinctive colors — the deep red of cherries and of tomatoes; the orange of carrots; the yellow of corn, mangos, and saffron; and the blue-purple of blueberries, blackberries, and grapes. The most well-known components of food with antioxidant activities are vitamins A, C, and E; beta-carotene; the mineral selenium; and more recently, the compound lycopene.
Roles of some antioxidants
— Vitamin E d-alpha tocopherol, is a fat soluble vitamin present in nuts, seeds, vegetable and fish oils, whole grains, fortified cereals, and apricots. Current recommended daily allowance (RDA) is 15 IU per day for men and 12 IU per day for women.
— Vitamin C Ascorbic acid is a water soluble vitamin present in citrus fruits and juices, green peppers, cabbage, spinach, broccoli, kale, cantaloupe, kiwi and strawberries. The RDA is 60 mg per day. Intake above 2000 mg may be associated with adverse side effects in some individuals.
— Beta-carotene is a precursor to vitamin A (retinol) and is present in liver, egg yolk, milk, butter, spinach, carrots, squash, broccoli, yams, tomato, cantaloupe, peaches, and grains. Because beta-carotene is converted to vitamin A by the body there is no set requirement. Instead the RDA is expressed as retinol equivalents (RE), to clarify the relationship.
Eating a diet rich in fruits and vegetables as part of an overall healthy diet may reduce your risk for stroke, cardiovascular diseases and diabetes. Fruits and vegetables can also stave off certain cancers, such as mouth, stomach, and colorectal cancer. They are rich in potassium and can also help to reduce the risk of developing kidney stones and bone loss. They are naturally low in fat and calories and they do not contain any cholesterol.
So how much fruit and vegetables do we really need each day? That depends on a lot of factors including age, sex and level of physical activity. As a general rule-of-thumb, young children need between 1 to 1 1/2 cups, and kids and adults require about 1 1/2 to 2 cups of fruit each day. As far as vegetables go, we need even more than what we should consume daily in the fruit category. Young children need about one cup and grown men need about three cups.
US Department of Agriculture (USDA)
Vegetables in the dark green category include bok choy, broccoli, collard greens, dark green leafy lettuce and kale. Orange vegetables include a host of different squash varieties, carrots, pumpkin and sweet potatoes. Dry beans and peas include black, garbanzo and kidney beans, lentils, lima beans and soy beans. Starchy vegetables include corn, peas, lima beans and potatoes and those in the “other” category include asparagus, cabbage, cucumbers, green beans, onions, tomatoes, zucchini and more.
For more ideas and tips for creating a healthy diet for yourself or family, go to www.mypyramid.gov.
By Eileen Ackerman