Free radicals (pro-oxidants) are atoms or molecules with unpaired electrons. These highly reactive substances can be formed in a number of ways, and once formed they may use their reactivity to damage important cellular components – such as the cell membrane – or macromolecules like DNA. This damage can lead to mutation, impaired function, and even cell death. To minimize potential damage from free radicals, the body utilizes a defense system of antioxidants.
Antioxidants are molecules that can safely interact with free radicals and terminate their reactivity before vital cellular components are damaged. Although there are several enzyme systems within the body that scavenge free radicals, the principle micronutrient (vitamin/mineral) antioxidants are vitamin E, beta-carotene, vitamin C, and selenium. The body cannot manufacture these micronutrients, so they must be acquired by diet. In addition, there are many plant-derived nutrients (phytonutrients) that can act as powerful antioxidants in the human body.
It is impossible to completely avoid damage from free radicals. Free radicals arise from sources both inside (endogenous) and outside (exogenous) our bodies. Oxidants that develop from processes within our bodies form as a result of normal breathing, metabolism, and inflammation. Exogenous free radicals form from environmental factors such as pollution, sunlight, strenuous exercise, smoking, and alcohol. Unfortunately, no antioxidant system is perfect, so cells and DNA damaged by oxidation accumulate as we age.
Health Benefits of Antioxidants
Antioxidants benefit your health by cleaning free radicals out of your bloodstream. They have a range of health benefits; some studies have shown that antioxdants reduce the signs of aging by minimizing wrinkles and preserving the texture of the skin. They can even protect your skin from sun damage, and reduce the incidence of sunburn.
Although antioxidants aren’t proven to treat any conditions, research has shown that antioxidants have also been implicated in the prevention of a number of degenerative, age-related disease, including:
- Cancer
- Cardiovascular disease
- Cognitive impairment
- Immune dysfunction
- Cataracts
- Macular degeneration
- Alzheimer’s
Different antioxidants benefit different parts of the body. For instance, the beta carotene found in carrots can help maintain eye health. The lycopene found in tomatoes can contribute to prostate health. The flavonoids found in tea, cocoa and chocolate are good for your heart, while the proanthocyanidins found in cranberries and apples can aid in the maintenance of the urinary tract.
In order to ensure that you get plenty of antioxidants in your daily diet, the USDA recommends that you eat a varied diet, with at least five servings of fruits and vegetables per day, and six to eleven servings of grains, including at least three servings of whole grains.
Sources of antioxidants
Plant foods are rich sources of antioxidants. They are most abundant in fruits and vegetables, as well as other foods including nuts, wholegrains and some meats, poultry and fish.
Good sources of specific antioxidants include:
- allium sulphur compounds – leeks, onions and garlic
- anthocyanins – eggplant, grapes and berries
- beta-carotene – pumpkin, mangoes, apricots, carrots, spinach and parsley
- catechins – red wine and tea
- copper – seafood, lean meat, milk and nuts
- cryptoxanthins – red capsicum, pumpkin and mangoes
- flavonoids – tea, green tea, citrus fruits, red wine, onion and apples
- indoles – cruciferous vegetables such as broccoli, cabbage and cauliflower
- isoflavonoids – soybeans, tofu, lentils, peas and milk
- lignans – sesame seeds, bran, whole grains and vegetables
- lutein – green, leafy vegetables like spinach, and corn
- lycopene – tomatoes, pink grapefruit and watermelon
- manganese – seafood, lean meat, milk and nuts
- polyphenols – thyme and oregano
- selenium – seafood, offal, lean meat and whole grains
- vitamin A – liver, sweet potatoes, carrots, milk, and egg yolks
- vitamin C – oranges, blackcurrants, kiwifruit, mangoes, broccoli, spinach, capsicum and strawberries
- vitamin E – vegetable oils (such as wheatgerm oil), avocados, nuts, seeds and whole grains
- zinc – seafood, lean meat, milk and nuts
- zoochemicals – red meat, offal and fish. Also derived from the plants that animals eat.
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