ORAC values refer to the Oxygen Radical Absorbance Capacity of a food, as determined by the U.S. Department of Agriculture and tests the ability of foods and other compounds to subdue oxygen free radicals. But what are free radicals, why do they need to be absorbed—and how do they relate to food?
Typically, stable molecules (in the body) contain pairs of electrons. When a chemical reaction breaks the bonds that hold paired electrons together, free radicals are produced. Free radicals contain an odd number of electrons, which makes them unstable, short-lived, and highly reactive in the body. As they combine with other molecules that contain unpaired electrons, new radicals are created, and an unhealthy chain reaction begins. In the human body, excessive oxidized free radicals cause tissue damage at the cellular level -- harming our DNA, mitochondria, and cell membrane—causing cells to function poorly or die.
To prevent free radical damage the body has a defense system of antioxidants. Antioxidants are molecules that defend the body from cellular damage by “sacrificing” themselves and ending the free radical chain reaction before vital molecules are harmed.
Antioxidants can be molecules our body produces, but also they can derive from the food we eat. You can increase your body’s ability to defend against free radicals by eating a diet high in antioxidants—foods high on the ORAC scale.
High ORAC-scoring Foods and their Effects
Studies have indicated the following benefits high-ORAC foods (on humans and study animals):
• High-ORAC foods raised the antioxidant power of human blood 10 to 25 percent.
• High-ORAC foods prevented some loss of long-term memory and learning ability in middle-aged study animals.
• High-ORAC foods maintained the ability of brain cells in middle-aged study animals to respond to a chemical stimulus--a function that normally decreases with age.
• High-ORAC foods protected study animals' tiny blood vessels--capillaries--against oxygen damage.
High ORAC-value Foods
Some of the highest-scoring ORAC foods include (in this order): Prunes, raisins, blueberries, blackberries, kale, raw spinach, cranberries, strawberries, pomegranates, raspberries, Brussels sprouts, plums, alfalfa sprouts, and broccoli florets.
A Healthy Diet High in Antioxidants
Although there are several enzyme systems within the body that scavenge free radicals, the main micronutrient (vitamin) antioxidants are vitamin E, beta-carotene, and vitamin C. Additionally, selenium, a trace metal that is required for proper function of one of the body's antioxidant enzyme systems, is sometimes included in this category.
The body cannot manufacture these micronutrients so they must be supplied in the diet—and good sources include vegetables, fruits, and certain types of tea. Here are some vital antioxidants and their food sources, to ensure adequate intake in the diet.
• Vitamin A: A study by the University of Arizona found that vitamin A has many protective effects. Vitamin A (retinol) helps bone and teeth development and promotes good vision. As an antioxidant, it protects cell membranes and fatty tissue, helps repair damage caused by air pollutants, and boosts the immune system. A deficiency in vitamin A can result in dry skin, brittle hair, vision problems, blindness, and increased susceptibility to respiratory infections. Foods rich in vitamin A include: liver, eggs, and some dairy products.
• Carotenoids: This class of antioxidants includes beta carotene, lutein, and lycopene. Research evidence indicates that carotenoids lower the risk of heart disease, some types of cancer, and help to strengthen the immune system. They are found in a variety of fruits and vegetables such as carrots, pumpkins, kale, spinach, tomatoes, and pink grapefruit. Some of the carotenoids like beta-carotene are also precursors to vitamin A. Food sources include kale, spinach, carrots, squash, broccoli, yams, tomato, cantaloupe, peaches, and apricots.
• Vitamin C: Vitamin C is a powerful antioxidant which helps strengthen the immune system, helps fight cardiovascular disease by protecting the lining of arteries from oxidative damage, and helps protect the body from smoke and air pollutants. Good sources include citrus fruits and juices, green peppers, cabbage, spinach, broccoli, kale, cantaloupe, kiwi, and strawberries.
• Vitamin E: Vitamin E is a potent antioxidant by itself, but is magnified when it is ingested with other antioxidants such as vitamin C, selenium, and beta carotene. Good sources include nuts, seeds, fish oils, whole grains, and apricots.
• Bioflavonoids: Bioflavonoids are a group of about 5,000 compounds that act as antioxidants. They have been shown to be beneficial for a variety of conditions including allergies, arthritis, diabetes, hypertension, and viral infections. A flavonoid is a pigment in plants and fruits that acts as an antioxidant to protect against damage from free radicals. In the body, flavonoids enhance the beneficial activities of vitamin C and therefore help keep the immune system strong. They occur primarily in vegetables and fruits (like apples) as well as green or black tea—and even dark chocolate.
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