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Antioxidants |
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| Antioxidant is substance that prevents or slows the breakdown of another substance by oxygen. Antioxidants are chemical substances that donate an electron to the free radical and convert it to a harmless molecule. Antioxidants are substances used by the body to protect itself from damage caused by oxidation. Oxidation is a process that causes damage in our tissues through the work of free radicals. An antioxidant is a chemical that prevents the oxidation of other chemicals. In the body, nutrient antioxidants such as beta-carotene (a vitamin A precursor), vitamin C, vitamin E, and selenium have been found to act as antioxidants.
Free radical production is actually a normal part of life, part of the equation of simply breathing in oxygen. The process of oxidation in the human body damages cell membranes and other structures including cellular proteins, lipids and DNA. When oxygen is metabolised, it creates 'free radicals' which steal electrons from other molecules, causing damage. The body can cope with some free radicals and needs them to function effectively. However, an overload of free radicals has been linked to certain diseases, including heart disease, liver disease and some cancers. Oxidation can be accelerated by stress, cigarette smoking, alcohol, sunlight, pollution and other factors. Antioxidants counteract these cellular by-products and bind with them before they can cause damage.
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Free radicals |
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| Harmful free radicals are toxic molecules of oxygen that damage every area of our bodies. A free radical is an unstable incomplete molecule because it is missing an electron which exists in pair in stable molecules. Free radicals steal an electron from another molecule, thereby create another free radical. This new free radical then duplicates the process, resulting in a chain reaction of events, which can ultimately damage the body. Free radicals are natural by-products of ongoing biochemical reactions in the body, including ordinary metabolic processes and immune system responses. The common free radicals are oxygen reactive species (ROS), namely, superoxide radical, hydroxyl radical, and peroxyl radical which can be internally produced by cellular metabolism, inflammaiton by immune cells and externally by radiation, pharmaceuticals, hydrogen peroxide, toxic chemicals, smoke, alcohol, oxidized polyunsaturated fats and cooked food. Free radicals can cause damage to parts of cells such as proteins, DNA, and cell membranes by stealing their electrons through a process called oxidation. Free radicals may cause heart damage, cancer, cataracts, and a weak immune system. |
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The health benefits of antioxidants |
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| Antioxidants work by neutralizing highly reactive, destructive compounds called free radicals. In biological systems, the normal processes of oxidation produce highly reactive free radicals. Antioxidants work by binding to the free radicals, they transforms
them into non-damaging compounds or repairscellular damage. Antioxidants are able to easily donate electrons to molecules in need of an electron, such as free radicals, before they steal one from someplace else, thus stabilize and prevent a damaging chain reaction. The antioxidant molecules interact with the oxygen free radicals and halt the spread of cancer causing cells with damaged DNA before other vital molecules are damaged. Antioxidants help neutralize the production of free radicals which are chemical complexes that cause harm to our cells and play a major role in the disease process. Antioxidants serve as a source of electrons that can be provided to free radicals without damaging the cell components. Antioxidants prevent unstable oxygen molecules (made unstable by loss of one electron) from interacting with other molecules (taking one of their electrons) and consequently causing them to become unstable, a process that starts the free-radical chain reaction.
Antioxidants help alleviate the symptoms and side effects of many of these diseases. According to the free radical theory, radicals damage cells in an organism, causing aging. Antioxidants break the free radical chain reaction by sacrificing electrons, and then humbly existing without stealing more. The body naturally circulates many nutrients for their antioxidant properties, and creates antioxidant enzymes just for the purpose of controlling free radicals and their chain reactions. Antioxidants are thought to thwart heart disease by preventing oxidation. Antioxidants combat chronic inflammation. Vitamin E suppresses platelet stickiness, acting as an anticoagulant to discourage the formation of clots that lead to heart attacks. Vitamin C decreases a blood factor needed to build clots. Antioxidants and cancer - Antioxidants fight cancer by neutralizing DNA-damaging free radicals. Antioxidants neutralize free radicals as the natural by-product of normal cell processes. Antioxidants prevent injury to blood vessel membranes, helping to optimize blood flow to the heart and brain, defend against cancer-causing DNA damage, and help lower the risk of cardiovascular disease and dementia, including Alzheimer's disease. |
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Commonly used antioxidant supplements |
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| Antioxidants are found in the nutrient antioxidants, vitamins A, C and E, and the minerals copper, zinc and selenium. Other dietary food compounds, such as the phytochemicals in plants and zoochemicals from animal products, are believed to have greater antioxidant effects than either vitamins or minerals. These are called the non-nutrient antioxidants and include phytochemicals, such as lycopenes in tomatoes, and anthocyanins found in cranberries. Some antioxidants are made in our cells and include
enzymes and the small molecules glutathione, uric acid, coenzyme Q10 and lipoic acid. Antioxidant compounds must be constantly replenished since they are "used up" (converted) in the process of neutralizing free radicals. Repair enzymes that can regenerate some antioxidants are superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), catalase and the other metalloenzymes.
Vitamin C (ascorbic acid) - Vitamin C neutralizes potentially harmful reactions in the watery parts of the body, such as the blood and the fluid inside and surrounding cells. Vitamin C may help decrease total and LDL cholesterol and triglycerides, as well as increase HDL levels. Vitamin C's antioxidant activity may be helpful in the prevention of some cancers and cardiovascular disease. The antioxidant properties of vitamin C are thought to protect smokers, as well as people exposed to secondhand smoke, from the harmful effects of free radicals. As a powerful antioxidant, vitamin C may help to fight cancer by protecting healthy cells from free-radical damage and inhibiting the proliferation of cancerous cells. The body does not produce vitamin C. Foods containing the highest sources of vitamin C include green peppers, citrus fruits and juices, strawberries, tomatoes, broccoli, turnip greens and other leafy greens, sweet and white potatoes, and cantaloupe.
Vitamin E - Vitamin E is the most effective, fat-soluble antioxidant known to occur in the human body. Vitamin E is an antioxidant that prevents free radical damage in biological membranes. Free radicals can cause cell damage that may contribute to the development of cardiovascular disease and cancer. Vitamin E helps protect against heart disease by limiting the oxidation of LDL-cholesterol. Vitamin E helps prevent oxidation of lipoproteins, particularly in smokers, and reduces the stickiness of platelets in the bloodstream. Vitamin E as an antioxidant helps to stabilize cell membranes and protect the tissues of the skin, eyes, liver, breast, and testes, which are more sensitive to oxidation. Vitamin E is found in many common foods, including vegetable oils (such as soybean, corn, cottonseed and safflower) and products made from these oils (such as margarine), wheat germ, nuts and green leafy vegetables, although the researchers evaluated only the pill form of the vitamin.
Beta-carotene - Consuming foods rich in beta-carotene appears to protect the body from damaging molecules called free radicals. Beta-carotene's antioxidant actions make it valuable in protecting against, and in some cases even reversing, precancerous conditions affecting the breast, mucous membranes, throat, mouth, stomach, prostate, colon, cervix, and bladder. Individuals with highest levels of beta-carotene intake have lower risks of lung cancer, coronary artery heart disease, stroke and age-related eye disease than individuals with lowest lvels of beta-carotene intake. The richest sources of beta-carotene are yellow, orange, and green leafy fruits and vegetables (such as carrots, spinach, lettuce, tomatoes, sweet potatoes, broccoli, cantaloupe, and winter squash).
Selenium - Selenium is a nonmetallic chemical element. Selenium is used in free radical elimination and other antioxidant enzymes, and also plays a role in the functioning of the thyroid gland. Selenium is the central element in glutathione peroxidase (GPx), an antioxidant enzyme that protects cells against the oxidative damage caused by peroxides and free radicals. Selenium forms part of the structure of the important antioxidant enzyme glutathione peroxidase, which in turn recycles glutathione. Dietary selenium comes from cereals, meat, fish, and eggs. Brazil nuts are a particularly rich source of selenium. |
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