 Show Some vitamins and minerals — including vitamins C and E and the minerals copper, zinc, and selenium — serve as antioxidants, in addition to other vital roles. "Antioxidant" is a general term for any compound that can counteract unstable molecules called free radicals that damage DNA, cell membranes, and other parts of cells. Because free radicals lack a full complement of electrons, they steal electrons from other molecules and damage those molecules in the process. Antioxidants neutralize free radicals by giving up some of their own electrons. In making this sacrifice, they act as a natural "off" switch for the free radicals. This helps break a chain reaction that can affect other molecules in the cell and other cells in the body. But it is important to recognize that the term "antioxidant" reflects a chemical property rather than a specific nutritional property. While free radicals are damaging by their very nature, they are an inescapable part of life. The body generates free radicals in response to environmental insults, such as tobacco smoke, ultraviolet rays, and air pollution, but they are also a natural byproduct of normal processes in cells. When the immune system musters to fight intruders, for example, the oxygen it uses spins off an army of free radicals that destroy viruses, bacteria, and damaged body cells in an oxidative burst. Some normal production of free radicals also occurs during exercise. This appears to be necessary in order to induce some of the beneficial effects of regular physical activity, such as sensitizing your muscle cells to insulin. Because free radicals are so pervasive, you need an adequate supply of antioxidants to disarm them. Your body's cells naturally produce some powerful antioxidants, such as alpha lipoic acid and glutathione. The foods you eat supply other antioxidants, such as vitamins C and E. Plants are full of compounds known as phytochemicals—literally, "plant chemicals"—many of which seem to have antioxidant properties as well. For example, after vitamin C has "quenched" a free radical by donating electrons to it, a phytochemical called hesperetin (found in oranges and other citrus fruits) restores the vitamin C to its active antioxidant form. Carotenoids (such as lycopene in tomatoes and lutein in kale) and flavonoids (such as flavanols in cocoa, anthocyanins in blueberries, quercetin in apples and onions, and catechins in green tea) are also antioxidants. News articles, advertisements, and food labels often tout antioxidant benefits such as slowing aging, fending off heart disease, improving flagging vision, and curbing cancer. And laboratory studies and many large-scale observational studies (those that query people about their eating habits and supplement use and then track their disease patterns) have noted antioxidant benefits from diets rich in them, particularly those coming from a broad range of colorful vegetables and fruits. But results from randomized controlled trials of antioxidant supplements (in which people are assigned to take specific nutrient supplements or a placebo) have not supported many of these claims. Indeed, too much of these antioxidant supplements won't help you and may even harm you. It is better to supply your antioxidants from a well-rounded diet. To learn more about the vitamins and minerals you need to stay healthy, read Making Sense of Vitamins and Minerals, a Special Health Report from Harvard Medical School. You may have heard a lot of talk about antioxidants. However, few people know what they are or how they work. This article tells you everything you need to know about antioxidants. Antioxidants are molecules that fight free radicals in your body. Free radicals are compounds that can cause harm if their levels become too high in your body. They’re linked to multiple illnesses, including diabetes, heart disease, and cancer. Your body has its own antioxidant defenses to keep free radicals in check. However, antioxidants are also found in food, especially in fruits, vegetables, and other plant-based, whole foods. Several vitamins, such as vitamins E and C, are effective antioxidants. Antioxidant preservatives also play a crucial role in food production by increasing shelf life. SUMMARY Free radicals are constantly being formed in your body. Without antioxidants, free radicals would cause serious harm very quickly, eventually resulting in death. However, free radicals also serve important functions that are essential for health (1). For example, your immune cells use free radicals to fight infections (2). As a result, your body needs to maintain a certain balance of free radicals and antioxidants. When free radicals outnumber antioxidants, it can lead to a state called oxidative stress. Prolonged oxidative stress can damage your DNA and other important molecules in your body. Sometimes it even leads to cell death. Damage to your DNA increases your risk of cancer, and some scientists have theorized that it plays a pivotal role in the aging process (3, 4). Several lifestyle, stress, and environmental factors are known to promote excessive free radical formation and oxidative stress, including:
Prolonged oxidative stress leads to an increased risk of negative health outcomes, such as cardiovascular disease and certain types of cancer. SUMMARY Antioxidants are essential for the survival of all living things. Your body generates its own antioxidants, such as the cellular antioxidant glutathione. Plants and animals, as well as all other forms of life, have their own defenses against free radicals and oxidative damage. Therefore, antioxidants are found in all whole foods of plant and animal origin. Adequate antioxidant intake is important. In fact, your life depends on the intake of certain antioxidants — namely, vitamins C and E. However, many other non-essential antioxidants occur in food. While they’re unnecessary for your body, they play an important role in general health. The health benefits associated with a diet rich in plants is at least partially due to the variety of antioxidants they provide (11). Berries, green tea, coffee, and dark chocolate are renowned for being good sources of antioxidants (12). According to some studies, coffee is the single biggest source of antioxidants in the Western diet, but this is partly because the average individual doesn’t eat that many antioxidant-rich foods (13, 14). Meat products and fish also contain antioxidants, but to a lesser extent than fruits and vegetables (15, 16). Antioxidants can increase the shelf life of both natural and processed foods. Therefore, they’re frequently used as food additives. For instance, vitamin C is often added to processed foods to act as a preservative (17). SUMMARY Antioxidants can be categorized as either water- or fat-soluble. Water-soluble antioxidants perform their actions in the fluid inside and outside cells, whereas fat-soluble ones act primarily in cell membranes. Important dietary antioxidants include:
Many substances that happen to be antioxidants also have other important functions. Notable examples include curcuminoids in turmeric and oleocanthal in extra virgin olive oil. These substances function as antioxidants but also have potent anti-inflammatory activity (19, 20). SUMMARY Dietary intake of antioxidants is essential for optimal health, but more is not always better. Excessive intake of isolated antioxidants can have toxic effects and may even promote rather than prevent oxidative damage — a phenomenon termed the “antioxidant paradox” (21, 22). Some studies even show that high doses of antioxidants increase your risk of death (23, 24). For this reason, most health professionals advise people to avoid high-dose antioxidant supplements, although further studies are needed before solid conclusions can be reached. Eating plenty of antioxidant-rich whole food is a much better idea. Studies indicate that foods reduce oxidative damage to a greater extent than supplements. For example, one study compared the effects of drinking blood-orange juice and sugar water, both of which contained equal amounts of vitamin C. It found that the juice had significantly greater antioxidant power (25). These results suggest that foods’ compounds work synergistically. Taking just one or two isolated nutrients won’t have the same beneficial effects. The best strategy to ensure adequate antioxidant intake is to follow a diet rich in various vegetables and fruits, alongside other healthy habits (26). However, low-dose supplements, such as multivitamins, may be beneficial if you are deficient in certain nutrients or unable to follow a healthy diet. SUMMARY Adequate antioxidant intake is essential to a healthy diet, although some studies suggest that high-dose supplements may be harmful. The best strategy is to get your daily dose of antioxidants from healthy plant foods, such as fruits and vegetables. Which of the following can neutralize the effects of free radicals before they cause?Antioxidants are found in certain foods and may prevent some of the damage caused by free radicals by neutralising them. These include the nutrient antioxidants, vitamins A, C and E, and the minerals copper, zinc and selenium.
Which of the following can lower the amount of free radicals in the body?Antioxidants are molecules which can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged. Although there are several enzyme systems within the body that disarm free radicals, the principal antioxidants are vitamin E, beta-carotene, vitamin C, and selenium.
Which of the following may protect against free radicals?Antioxidants, such as vitamins C and E and carotenoids, may help protect cells from damage caused by free radicals. Other naturally occurring antioxidants include flavonoids, tannins, phenols and lignans.
Which of the following diseases are linked to free radical damage?Alzheimer's disease. Parkinson's disease. diabetes. cardiovascular conditions such as high blood pressure, atherosclerosis, and stroke.
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Which of the following can neutralize the effects of free radicals before they cause much damage?
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