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antioxidants

What Is It?
Health Benefits
Forms
Dosage Information
Guidelines for Use
General Interaction
Possible Side Effects
Cautions  
References
Evidence Based Rating Scale


 

What Is It?

Over the last several decades, scientists have discovered that the body's formation of unstable oxygen molecules called Free radicals is unavoidable--every cell produces tens of thousands of them each day. We're also exposed to free radicals in the environment on a daily basis. Cigarette smoke, for instance, is one of the most concentrated sources of free radicals.

Left unchecked, free radicals can cause extensive cell damage and contribute to an extensive list of chronic diseases. Luckily, the body does have a defense system against these rogue "oxidant" compounds: antioxidants. Found in numerous fruits and vegetables, and even produced naturally by the human body, antioxidants literally "mop up" free radicals.

The more familiar antioxidants include vitamins E and C; the carotenoids (such as beta-carotene); selenium; and flavonoids (anthocyanidins, Polyphenols, quercetin). All of these are readily supplied by a varied and well-balanced diet. Probably lesser known are the so-called "factory-installed" antioxidants produced by the body itself; these include glutathione, alpha-lipoic acid, and coenzyme Q10.

Antioxidants in the form of dietary supplements have been available for years, and while they can't substitute for a healthy diet and lifestyle, they can play a role in reinforcing your overall health and resilience. Antioxidant supplements are best taken in the form of combination products because multiple antioxidants appear to work together synergistically far more effectively than a single antioxidant, no matter how high the dose. (1, 2) In addition, some supplements, such as zinc, copper, and selenium, are necessary to actually strengthen the body's own antioxidant protection system.

Most antioxidant combinations contain a standard ingredient base, namely Vitamin C, vitamin E, beta-carotene, and the Mineral selenium. After that, there is a great deal of variation. Some combinations include newly discovered antioxidants, such as proanthocyanidins (flavonoids found in grape seed Extract, pine bark, and red wine), N-acetylcysteine (NAC), alpha-lipoic acid, coenzyme Q10, and zinc. Others feature potent herbal antioxidants such as ginkgo biloba or green tea.

Health Benefits

When you have too few antioxidants to counteract your free radicals, significant damage can occur, leading to a variety of chronic degenerative diseases, ranging from stroke and fibromyalgia, to sinusitis, arthritis, vision problems, and even Parkinson's and Alzheimer's disease. A poor diet, cigarette smoking, environmental pollutants, and ultraviolet (UV) radiation from the sun also increase the free-radical load, creating a situation known as "Oxidative stress."

Ongoing research, however, indicates that a high antioxidant intake really does help stave off some of these illnesses, specifically the risk of various cancers--those of the stomach, prostate, colon, breast, bladder, and pancreas among others--over a person's lifetime. Antioxidants also appear to boost overall health and resilience.

Specifically, antioxidants may help to:

Prevent heart disease. Antioxidants such as vitamin E halt the oxidation of LDL ("bad") cholesterol. (3, 4) This is beneficial because once LDL is oxidized it can become trapped in the artery walls, damaging the lining of the artery and leading to the accumulation of fatty deposits called plaque. Eventually, plaque can build up so much that it narrows the space within the artery. Blood clots may form on the plaque and completely block the flow of blood. In a coronary artery, this will cause a heart attack. In an artery within the brain, the result is a stroke.

However, research has been conflicting in this area. Observational studies have linked increased intake of vitamin E with decreased risk of cardiovascular events in men and women (5, 6, 7), but clinical trials have not supported this epidemiological evidence (8). More research is needed to

Control high blood pressure. By scouring out the free-radical molecules that can cause oxidative damage (to LDL or "bad" cholesterol, specifically), antioxidants help your blood vessels stay flexible and able to dilate, which in turn helps keep your blood pressure from worsening.

In fact, until recently scientists believed that regular intake of vitamin C, a major antioxidant, could help lower blood pressure by widening blood vessels. Several studies seemed to indicate that this was true. However, conflicting trials and meta-analysis found that vitamin C may actually speed up--not slow down--hardening of the arteries. The efficacy of vitamin C in preventing hypertension, therefore, remains controversial. Until more about the surprising conflicting evidence is understood, it's probably best to opt for a mixed combination of antioxidants rather than single, high doses of vitamin C.

In addition to vitamin C, coenzyme Q10 has been shown to help lower blood pressure and reduce the dosage or need for conventional medications. (9, 10, 11)

Protect against diabetes-related damage. One of the reasons that diabetes is so important to monitor closely is that it can affect so many organ systems: eyes, blood vessels, heart, kidneys. It's thought that the altered metabolic state brought about by diabetes produces free radicals, which in turn are responsible for these types of damage. That's why it makes so much sense, especially if you have diabetes, to use antioxidants to reinforce your defense system against free-radical damage. A 2002 study found vitamin C supplementation of 500 mg daily – in conjunction with conventional treatments – lowered blood pressure and decreased arterial stiffness in patients with type 2 diabetes. (12) And, vitamin C taken with vitamin E has been shown to reduce the excretion of albumin by about 19 percent when taken by patients with type 2 diabetes for four weeks, possibly reducing the risk of end-stage renal disease in these patients. (13)

Block the development of certain cancers. Stomach, prostate, colon, breast, bladder, esophageal, and pancreatic--these are just a few of the types of cancer that may be prevented by antioxidants. In a comprehensive review of 130 studies examining the connection between diet and cancer, researchers at the University of California at Berkeley found that 92% of the studies showed that taking antioxidant supplements or eating antioxidant-rich foods significantly reduced the risk of cancer. (14) Caution is recommended with use in smokers, some studies have shown a possible increase in lung cancer risks in smokers who take certain anti-oxidants.

Slow the effects of aging. According to one theory, antioxidants such as coenzyme Q10 may impede the excessive formation of free radicals that probably play a part in the wrinkling of skin, loss of muscle elasticity, reduced immunity, and memory failures. (15) So although you can't completely prevent aging, you may be able to minimize some of its effects with antioxidants.

Note: Antioxidants have also been found to be useful for a number of other disorders. For information on these additional ailments, see our Dosage Recommendations Chart for Antioxidants.

Forms

  • tablet
  • softgel
  • capsule

Dosage Information

Special tips:

--Take a high-potency multivitamin/mineral and a well-balanced antioxidant complex every day. It may be necessary to adjust the dosages outlined below to account for your own daily vitamin regimen. All of these supplement recommendations also assume you are eating a healthful diet.

--Opt for an antioxidant combination product rather than a single antioxidant supplement. The latest studies indicate that a single antioxidant at high doses will not provide the same degree of protection as a combination of antioxidants. In fact, a single antioxidant used by itself may be harmful, becoming a free radical itself. When other antioxidants are present, they all help recycle each other. Combination products are also more convenient and less expensive than individual antioxidants.

For general good health: Look for an antioxidant complex that contains at least the nutrients listed here in the recommended dosage. Combination products vary considerably. In general, look for a product that will increase the number of different antioxidants you take each day rather than simply duplicating those already found in your daily multiple vitamin.

Basic antioxidant vitamins:

  • 800-1,000 mg vitamin C
  • 400 IU vitamin E
  • 100-200 mcg selenium
  • 10,000-50,000 IU mixed carotenes
  • 15-30 mg zinc
  • 1-2 mg copper
"Enriching" antioxidants:
  • 50-100 mg proanthocyanidins (including flavonoids, such as grape seed extract, pine bark, and red wine)
  • 50-150 mg NAC (N-acetylcysteine)
  • 50-100 mg alpha-lipoic acid
  • 10-30 mg coenzyme Q10
  • 30 mg ginkgo biloba
  • 25-100 mg green tea extract
Different dosages or other antioxidants may be recommended for specific health conditions. See the individual entries in the WholeHealthMD Reference Library for more information.

Guidelines for Use

  • Take antioxidant supplements with meals. Foods that contain a little bit of fat enhance the absorption of vitamin E and carotenoids.

  • It's best to take antioxidant supplements in two doses during the day. That way, you are constantly providing your body with a fresh supply.

  • Opt for natural vitamin E supplements. Studies show that E derived from natural sources is better absorbed than synthetic forms of the vitamin. But don't rely simply on the word ''natural'' on the label. Check the ingredient list for d-alpha tocopherol (a natural form of vitamin E). Don't buy those that contain dl-alpha tocopherol.

  • In addition to antioxidant supplements, it is important to include plenty of vegetables, fruits, and other plant foods in your diet. Many of the flavonoids are not available in supplement form, and there are probably many undiscovered beneficial compounds in plant foods.

    A number of important antioxidants are found in foods:

    • Vitamin C is plentiful in fruits and vegetables, especially dark leafy greens, citrus fruits, strawberries, red peppers, kiwi, papaya, broccoli, cabbage, and cauliflower. If you eat six servings or more of fruits and vegetables each day, you may not need a vitamin C supplement.

    • Carotenoids are found in orange fruits and vegetables and in red and dark green vegetables. Apricots, carrots, cantaloupe, sweet potatoes, and winter squash are good sources of beta-carotene. Lycopene is found in tomatoes. Lutein is found in dark green leafy vegetables and red peppers. Alpha-carotene is found in pumpkin, carrots, yellow peppers, and winter squash.

    • Vegetable oils, nuts and seeds, wheat germ, and dark leafy greens all contain vitamin E. But it's impossible to get therapeutic amounts of the vitamin from diet alone. For example, you'd need to eat 25 pounds of almonds or consume nearly 9 cups of canola oil to get 400 IU of vitamin E.

    • Flavonoids are found in a wide array of fruits and vegetables. In particular, beets contain anthocyanidins, green tea contains polyphenols, and apples and onions contain quercetin. Other good flavonoid sources include citrus fruits, berries, and red wine.

  • General Interaction

  • People on anticoagulant drugs should talk to their doctor before taking antioxidant complexes containing more than 400 IU of vitamin E. This popular antioxidant can have an anticoagulant effect of its own when taken in higher doses.

  • Cancer patients undergoing chemotherapy should talk to their oncologists about antioxidant supplementation.
  • Possible Side Effects 

    Antioxidant combinations are extremely safe and virtually free from side effects. Some people with sensitive digestive systems get mild nausea or upset stomach with virtually any Nutritional supplement, so your best bet is to take supplements with food and avoid taking them on an empty stomach.

    Cautions

    Antioxidant combinations are safe to use during pregnancy and when breast-feeding.

    References 

    1. May JM, Qu ZC, Whitesell RR, Cobb CE. Ascorbate recycling in human erythrocytes: role GSH in reducing dehydroascorbate. Free Radic Biol Med. 1996;20:543-551.

    2. Chen H, Tappel AL. Protection by vitamin E, selenium, Trolox C, ascorbic acid palmitate, acetylcysteine, coenzyme Q, beta-carotene, canthaxanthin, and (+,–) catechin against oxidative damage to liver slices measured by oxidized heme proteins. Free Radic Biol Med. 1994;16:437-444.

    3. Kagan VE, Serbinova EA, Forte T, et al. Recycling of vitamin E in low density lipoproteins. J Lipid Res. 1992;33:385-397.

    4. Wiklund, O, Mattsson L, Bjornheden T, et al. Uptake and degradation of low density lipoproteins in atherosclerotic rabbit aorta: role of local LDL modification. J Lipid Res. 1991;32:55-62.

    5. Stampfer MJ, Hennekens CH, Manson JE, et al. Vitamin E consumption and the risk of coronary disease in women. N Engl J Med. 1993;328:1444-9.

    6. Rimm EB, Stampfer MJ, Ascherio A, et al. Vitamin E consumption and the risk of coronary heart disease in men. N Engl J Med. 1993;328:1450-6.

    7. Kushi LH, Folsom AR, Prineas RJ, et al. Dietary antioxidant vitamins and death from coronary heart disease in postmenopausal women. N Engl J Med. 1996;334:1156-62.

    8. Vivekananthan DP, Penn MS, Sapp SK, et al. Use of antioxidant vitamins for the prevention of cardiovascular disease: meta-analysis of randomized trials. Lancet. 2003;361:3017-23.

    9. Langsjoen P, Willis R, Folkers K. Treatment of essential hypertension with coenzyme Q10. Mol Aspects Med. 1994;S265-72.

    10. Singh RB, Niaz MA, Rastogi SS, et al. Effect of hydrosoluble coenzyme Q10 on blood pressures and insulin resistance in hypertensive patients with coronary artery disease. J Hum Hypertens. 1999;13:203-8.

    11. Hodgson JM, Watts GF, Playford DA, et al. Coenzyme Q10 improves blood pressure and glycaemic control: a controlled trial in subjects with type 2 diabetes. Eur J Clin Nutr. 2002;56:1137-42.

    12. Mullan BA, Young IS, Fee H, McCance DR. Ascorbic acid reduces blood pressure and arterial stiffness in type 2 diabetes. Hypertension. 2002;40:804-9.

    13. Gaede P, Poulsen HE, Parving HH, Pedersen O. Double-blind, randomized study of the effect of combined treatment with vitamin C and E on aluminuria in Type 2 diabetic patients. Diabet Med. 2001;18:756-60.

    14. Block G. The data support a role for antioxidants in reducing cancer risk. Nutr Rev. 1992 Jul;50(7):207-13.

    15. Hoppe U, Bergemann J, Diembeck W, et al. Coenzyme Q10, a cutaneous antioxidant and energizer. Biofactors. 1999;9:371-8

    16. Moyano D, Sierra C, Brandi N, Artuch R, Mira A, García-Tornel S, Vilaseca MA Antioxidant status in anorexia nervosa. Int J Eat Disord. 1999 Jan;25(1):99-103.

    Evidence Based Rating Scale 

    The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies with what our clinical advisors have found to be efficacious in their personal practice. This tool is meant to simplify which supplements and therapies demonstrate promise in the treatment of certain conditions. This scale does not take into account any possible interactions with any medication/ condition/ or therapy which you may be currently undertaking. It is therefore advisable to ask your doctor before starting any new treatment regimen.

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      Date Published: 01/01/2008

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