- Our bodies are constantly under attack. The assailants, nasty molecules called free radicals, attack the body’s cells, causing cellular damage that can flourish into chronic diseases and conditions. By knowing how to get the most out of antioxidants — our primary defense against environmental stressors — we can improve our health and maybe even add a few more years to our lives.
Free radicals, unstable molecules that damage the structure of healthy cells, contribute to the aging process and the development of such health conditions as cancer, heart disease, Alzheimer’s disease and arthritis. Although the body creates some free radicals during normal metabolic processes, most are caused by such environmental factors as pollution, radiation, sun exposure, cigarette smoke and herbicide.
Here’s how it works: When a molecule splits in such as way that leaves it with one unpaired electron, it becomes unstable and tries to recapture the electron by stealing it from another molecule. That attacked molecule then becomes an unstable free radical itself, setting off a chain reaction.
Antioxidants — essential nutrients that include vitamins A, C and E, beta-carotene, lycopene and selenium — protect the body from cellular damage by giving electrons to free radicals without becoming free radicals themselves. But if antioxidants are unavailable to stop these attacks or if too many free radicals are produced, cell damage can occur, leading to a multitude of chronic diseases.
Although laboratory evidence suggests that antioxidants may slow or even prevent the development of cancer, large-scale clinical trials have reached inconsistent conclusions.
Here’s a guide to the best-known antioxidants, where to find them and how, in addition to neutralizing free radicals, they can benefit you.
Vitamin A and Beta-Carotene
Vitamin A is a fat-soluble vitamin that helps to form and maintain healthy skin, teeth, bones and soft tissue. Also known as retinol because it produces the pigment in the retina of the eye, Vitamin A promotes good vision, especially in low light. It also plays a role in reproduction, breastfeeding and immune function.
There are two types of vitamin A: preformed vitamin A and provitamin A carotenoids.
Preformed vitamin A (retinol, retinoic acid) can be found in foods from animal sources, such as eggs, whole milk, cheese, meat, liver, fish, cod liver oil, and some fortified foods.
Provitamin A carotenoids, such as beta-carotene, are highly pigmented fat-soluble compounds found in plant food that the body converts into vitamin A. According to the National Institutes of Health, beta-carotene and other carotenoids provide approximately 50 percent of the vitamin A needed in the average American diet.
Beta-carotene can be found in brightly colored fruits and vegetables, including cantaloupe, pink grapefruit, apricots, peaches, carrots, pumpkins, sweet potatoes, winter squash, beets, broccoli, spinach, kale and most leafy, dark green vegetables. The more intense the color, the higher the beta-carotene content.
Vitamin C, also known as ascorbic acid, is a powerful nutrient necessary for the growth and repair of tissues throughout the body. It stimulates the production of collagen — an important protein used to make skin, bones, cartilage, tendons, ligaments and blood vessels — and it helps heal wounds, form scar tissue, and repair and maintain teeth and bones.
As an antioxidant, Vitamin C not only neutralizes free radicals, but also heals wounds and regenerates other antioxidants, such as vitamin E. In fact, a 2006 study found that Vitamin C concentrations regenerated some of the depleted Vitamin E levels in cigarette smokers. And 2009 research from England’s University of Leicester shows that ascorbic acid 2-phosphate, a derivative of vitamin C, can reverse DNA damage.
The human body is unable to make vitamin C on its own, and because it is water-soluble, the body can’t store it. That means you need a continuous supply of vitamin C in your diet. The best sources are raw or lightly cooked fruits and vegetables.
Fruits high in vitamin C include acerola cherries; black currants; cantaloupe; citrus fruits, such as oranges and grapefruits; guavas; kiwis; mangos; papayas; pineapples; strawberries, raspberries, blueberries and cranberries; tomatoes; and watermelon. Vegetables high in vitamin C include bell peppers, yellow, red or green; broccoli; Brussels sprouts; cabbage; cauliflower; leafy greens, including kale, mustard greens, turnip greens, chard, spinach and watercress; potatoes, sweet and white; and winter squash.
Pregnant or breastfeeding women, smokers, burn victims and people recovering from surgery may need extra vitamin C in their diets.
Vitamin E is a fat-soluble vitamin that helps to strengthen the immune system against viruses and bacteria. It aids the formation of red blood cells and helps the body use vitamin K, a fat-soluble vitamin that helps blood clot properly. Its antioxidant properties also help protect the skin from the sun’s damaging rays.
The body cannot produce vitamin E, so it’s important to get it through dietary sources. Vitamin E can be found in nuts, including almonds, peanuts and hazelnuts; seeds, notably sunflower seeds; whole grains; avocados; green leafy vegetables, including spinach and broccoli; vegetable oils, such as corn, safflower, sunflower, soy bean and wheat germ oils; and fortified breakfast cereals, juices, margarines and spreads.
Lycopene is a carotenoid that’s red in color and most notably found in tomatoes. Unlike beta-carotene, a carotenoid that the body converts into vitamin A, lycopene does not have a vitamin A function. But it is considered a more powerful antioxidant than both beta-carotene and vitamin E.
In fact, a 1989 study showed that lycopene was the most efficient biological scavenger of free radicals. And a 2005 study published in the British Journal of Nutrition showed that regular lycopene consumption, particularly from tomato products, helped improve cellular antioxidant protection.
Numerous studies have linked high lycopene intake with reduced incidence of cancer, cardiovascular disease and macular degeneration.
The best sources of lycopene include tomatoes, watermelon, pink grapefruit, guavas and papayas.
Selenium is a mineral found in the soil that naturally occurs in water and some foods. Selenium is incorporated into proteins to make selenoproteins, important antioxidant enzymes that help prevent cellular damage from free radicals, help regulate thyroid function and play a role in immune function. People only need to consume a small amount of this mineral.
Selenium content varies, depending on the content in the soil where the source plants are grown or animals raised. For instance, in the United States, selenium levels are highest in the soils in the high plains of Nebraska and the Dakotas and lowest in the Eastern Coastal Plain and Pacific Northwest.
Good selenium sources include nuts, notably Brazil nuts (which according to the U.S. Department of Agriculture has extremely high selenium levels, so don’t eat too many) and walnuts; fish, such as tuna, cod, halibut, salmon, red snapper and herring; beef; poultry; and grains, such as barley.
Ask your health care provider how antioxidants can help you.