Antioxidants
 
Antioxidants are compounds that help prevent free-radical damage are known as antioxidants or "free-radical scavengers". These protective compounds are common in our foods such as Vitamins A, C, E and Coenzyme Q10. Also carotenes such as beta-carotene, which is high in carrots, and the trace mineral selenium, are well known antioxidants. Lycopene, which gives tomatoes their colour, is a powerful antioxidant. Grape seed, maratime pine bark and green tea extracts contain catechins that have potent antioxidant properties and have become popular natural medicines.Antioxidants have benn shown to play an important role in disease prevention.
Free-radicals: These are highly reactive molecules that contribute to cell damage and disease. Although the body produces free radicals our load is increased with environmental exposure such as chemicals, radiation and X rays and also ingested compounds in our food and drinks. Some sources are air pollution, insecticides, radiation such as from computers, and mobile phones, fried or burnt foods, alcohol and coffee. Cigarette smoke has extremely high levels of free radicals. Free radicals are toxic because they damage the body’s cells and DNA and oxidize vital compounds in the body. A familiar example of oxidation is an apple slice that turns brown--when an apple is cut into slices and left on the counter for 30 minutes, it begins to turn brown. But if the slices are coated with lemon juice immediately after cutting, they will remain their original color. The vitamin C (an antioxidant) in the lemon juice prevents oxidation, or the browning process. In the body, this oxidative damage by free radicals is a major contributor to causing cancer. Free radicals may also play a role in the promotion of heart disease, Alzheimer’s disease, age-related macular degeneration and cataracts, and decreased immune function. To make the situation worse, free radicals accumulate in the body over time and may also convert stable compounds in the body into free radicals. This may be one reason why cancer and these other diseases are more prevalent with age.
As many of these protective compounds are abundant in fresh fruit and vegetables it is wise to make sure we eat plenty of them each day. People with cancer are usually recommended to also have fresh fruit and vegetable juices each day as their body's needs are greater and juicing provides the extra nourishment, including minerals, with minimum energy wasted on digestion. For people that are weak and have a lack of appetite, juicing can provide high quantities of essential antioxidants, vitamins and minerals that are easily absorbed. It is also possible that a supplment may be needed.

Which Antioxidants are needed?

Most scientists agree that vitamins C and E, beta-carotene, and selenium play a role in prevention of various degenerative diseases. However, new research indicates that there may be many other antioxidants that are also important for maintaining good health. Each antioxidant has its own job to do in the body, and some even work together. Lutein and zeaxanthin (found in green leafy and yellow vegetables) are concentrated in the lens and retina of the eye and have been associated with a reduced risk of cataracts and macular degeneration.

Lycopene (found in tomato products) is concentrated in the prostate gland in men and may play a role in prevention of prostate cancer. Vitamin C (found in citrus fruits and some green vegetables) is a water-soluble antioxidant and works in the watery areas of the body. On the other hand, vitamin E (found in vegetable oils, nuts, and seeds) is a fat-soluble antioxidant and works in fat-containing parts of the body, such as the outer lining (membrane) of cells. Vitamin C can also help regenerate the antioxidant activity of vitamin E after vitamin E has been used as an antioxidant in the body. Probably the best prevention plan is a variety of antioxidants from a variety of sources.

Getting a variety of antioxidants is also important because each antioxidant targets certain types of damaging free radicals--getting a variety will help cover all of your health bases.

Vitamin C: Vitamin C is a water-soluble antioxidant nutrient. It has been shown to be a factor in reducing risk of various types of cancer, reducing risk for heart disease, improving immune function (especially in combination with vitamin E), and reducing risk for cataracts.

Vitamin E: Vitamin E is a fat-soluble antioxidant nutrient and is the primary antioxidant found in the lipid-containing tissues of the body (such as cell membranes, or linings). Vitamin E’s antioxidant activity may be protective against atherosclerosis (a condition in which arteries narrow and may lead to heart attack), nervous system disorders, and progression of the human immunodeficiency virus (HIV) that leads to AIDS. The natural form of vitamin E (d-alpha-tocopherol) is at least twice as biologically active as the synthetic form (dl-alpha-tocopherol). Therefore, when using a dietary supplement, the natural form is preferred.

Carotenoids: Carotenoids are the pigments that provide the red, yellow, orange, and green colors of fruits and vegetables--more than 500 carotenoids have been identified! The primary dietary carotenoids include beta-carotene, alpha-carotene, lycopene, lutein, zeaxanthin, and beta-cryptoxanthin. Beta-carotene, alpha-carotene, and beta-cryptoxanthin can be converted into vitamin A in the body, but only in amounts that are required by the body. In other words, there is no risk for vitamin A toxicity by eating too many carrots--only a risk for an orange glow to the skin.

Beta-carotene is a fat-soluble antioxidant that is a member of the carotenoid family and may play a role in reducing risk for heart disease and prostate cancer. Observational research has associated beta-carotene with a decreased risk of various types of cancer; however, two studies indicated that smokers who supplemented with beta-carotene had an increased risk for lung cancer versus smokers who did not supplement. Research has not yet discovered why beta-carotene supplementation produced these unexpected results, but scientists have proposed several possible explanations: that beta-carotene may act negatively in the lungs when a carcinogen (tobacco smoke) is present, and/or that beta-carotene may have an anti-cancer effect only when consumed with other carotenoids or other antioxidants. More research is needed to determine the cause of these research results. Until those answers are available, it’s recommended that smokers avoid supplementing with high amounts of isolated beta-carotene. For more information on beta-carotene, see the Health Data Bank paper “Beta-carotene.”

Lycopene: Lycopene, a member of the carotenoid family, is a fat-soluble pigment responsible for the red color of certain fruits and vegetables. Its pigment protects the plant from damage by oxygen and light. Lycopene’s antioxidant activity may play a role in protection against prostate cancer and heart disease.

Lutein and zeaxanthin: Lutein and zeaxanthin, members of the carotenoid family, are fat-soluble pigments responsible for the yellow or green color of certain fruits and vegetables. Their pigment protects the plant from damage by oxygen and light. They are found in the lens and macula of the eye and thought to be protective against age-related macular degeneration (ARMD) and age-related cataracts.

Selenium: Selenium is an essential trace mineral, which means that it must be consumed in the diet for good health. Selenium is also an antioxidant and may play a role in reducing risk for heart disease and cancer, including prostate, colorectal, lung, and possibly other types of cancer. Selenium works with vitamin E in fighting free radicals and is also required for the function of an important antioxidant enzyme (glutathione peroxidase) in the immune system. It may even be involved in slowing the progression of the human immunodeficiency virus (HIV), which leads to AIDS.

Coenzyme Q10 (CoQ10): CoQ10 is a member of the ubiquinone family. This fat-soluble antioxidant also takes part in energy production in the body’s cells. The body produces CoQ10, but production decreases with age. Research indicates that supplementation with CoQ10 may be beneficial for heart health problems including recovery after congestive heart failure or heart attack. It may also play a role in reducing the effects of periodontal disease.

Alpha-lipoic acid: Alpha-lipoic acid is produced in the body and found in animal and plant sources. It’s a highly potent antioxidant that may help protect against atherosclerosis and may help slow progression of diabetic neuropathy and HIV. Alpha-lipoic acid has a double benefit by recycling other important antioxidants, such as vitamin C, vitamin E, coenzyme Q10, and glutathione.

Grape seed extract: Grape seed extract contains compounds called oligomeric proanthocyanidins (OPCs), or sometimes called procyanidolic oligomers (PCOs). These compounds are potent antioxidants that may protect against heart disease and cancer. OPCs have also been shown to have an anti-inflammatory effect.

Pine bark extract: Pine bark extract contains compounds called flavonoids. More than 4,000 flavonoids have been identified in plants and many are antioxidants. Pine bark extract may be heart protective and beneficial in some vascular disorders (circulation problems). It may also have anti-inflammatory benefits.

Green tea: Green tea contains compounds called catechins that have antioxidant activity. The most potent green tea catechin is called epigallocatechin gallate (EGCG). Catechins may protect against cancer and atherosclerosis and may have anti-inflammatory benefits.

Quercetin: Quercetin is a member of a group of compounds called flavonoids. Its antioxidant activity may play a role in protection against cancer. Preliminary research indicates it may have beneficial effects on immune function, allergies, capillary health, stomach health, and diabetic complications such as cataracts and neuropathy. It has also been shown to have anti-inflammatory properties.

N-acetyl cysteine: N-acetyl cysteine (NAC) is a derivative of the protein amino acid L-cysteine. NAC has antioxidant activity and also may be converted to L-cysteine in the body, which in turn may be used to form the antioxidant glutathione. Glutathione is a potent antioxidant and important for healthy immune function. NAC may play a role in benefiting liver and heart health, immune function, and pulmonary and respiratory problems.
 

Turmeric: Turmeric contains compounds called curcuminoids, which are antioxidants. Curcuminoids may have anti-cancer and anti-inflammatory benefits. Preliminary research indicates it may also have antiviral and antifungal benefits and possibly protect against atherosclerosis.

 
Ellagic acid: Ellagic acid is a powerful antioxidant. Preliminary research indicates it may protect against cancer.

 
Hesperidin: Hesperidin is a member of the flavonoid family and has been shown to have antioxidant activity. It may be beneficial for circulatory and heart health.

 
Reishi mushroom: Reishi mushroom extract has been shown to have antioxidant effects. Compounds called triterpenes are thought to be responsible for its antioxidant activity. Reishi mushroom may play a role in immune function and possibly cancer prevention.

Natural Sources of Antioxidants?
Fruits and vegetables are the most abundant sources of antioxidants. Usually the more colorful fruits and vegetables, such as the deep orange, yellow, green, red, and purple varieties, are the richest sources of antioxidants.The problem is that many Americans are not eating enough fruits and vegetables in their diet, they are not eating many of the colorful antioxidant-rich fruits and vegetables, and they are not eating a variety of antioxidant-rich foods. A recent study indicates that 30% of all vegetables consumed by Americans are white potatoes, and one-third of those potatoes are consumed in the form of French fries. Most of the lettuce and tomatoes consumed are consumed as condiments. The most commonly consumed fruits and vegetables in the American diet (iceberg lettuce, French fries, bananas, tomatoes, and orange juice) do not provide a powerful array of antioxidant ammunition for disease prevention. The following table provides food sources of antioxidants:

What About Antioxidant Supplements?

Eating a wide variety of colorful fruits and vegetables, whole grains, nuts, and seeds is the best route to getting antioxidants. This will provide not only a variety of health-protecting antioxidants, but many other nutrients and phytochemicals (plant chemicals) that may benefit health and help prevent disease. The National Cancer Institute recommends at least five or more servings of fruits and vegetables daily. Research indicates that a daily intake of five to ten servings of fruits and vegetables is associated with reduced cancer risk.

Because most Americans are not consuming the amount or quality of fruits and vegetables to obtain potential disease-fighting benefits, supplements may help fill in the gaps. Many nutrition-oriented healthcare professionals recommend starting with a blend of the basic antioxidant vitamins and minerals. This may include a daily intake of vitamin C (250-500 mg), vitamin E (200-400 IU), selenium (100-200 mcg), and beta-carotene (10,000-25,000 IU) taken with other carotenoids such as alpha-carotene, lutein, and zeaxanthin. Supplementation may be beneficial for those antioxidants that are not available in significant amounts in foods (such as vitamin E) or those antioxidants found in foods that may have other negative health effects (high-fat meats or egg yolks may raise cholesterol). And some antioxidants, such as pine bark extract, may only be obtained in supplement form.
 

There is much more to learn and discover about antioxidants, but in the meantime, one message is clear--reduce exposure to free radicals, eat more colorful fruits and vegetables, and supplement when needed.

References:

 
 
 
Antioxidant Food Sources

Vitamin C

Citrus fruits (oranges, grapefruits, tangerines), berries, broccoli, Brussels sprouts, collards, guava, kale, turnip greens, sweet peppers, cabbage, cauliflower, spinach, watercress, melons.
Vitamin E
Unprocessed vegetable oils. Smaller amounts are found in whole grains, dark-green leafy vegetables, nuts, legumes.
Beta-carotene
Yellow-orange or green fruits and vegetables such as carrots, kale, kohlrabi, parsley, spinach, turnip greens, apricots.

Lycopene

Tomatoes and tomato-based products (tomato sauce, etc.), watermelon, papaya, pink grapefruit, and pink guava. Processed tomato products contain more lycopene than fresh tomatoes.

Lutein and zeaxanthin

Corn, egg yolks, and green vegetables and fruits (broccoli, Brussels sprouts, kale, cabbage, green beans, green peas, spinach, kiwi, and honeydew melon).
Selenium
Seafood, meat, and organ meats. Content of selenium in plant sources (whole grains and seeds) depends on selenium content of the soil.
Coenzyme Q10
Organ meats (especially hearts) are the richest sources. Beef and chicken contain smaller amounts.
Alpha-lipoic acid
Red meat, yeast, and liver.
Grape seed extract
(proanthocyanidins)
Grape seeds.
Pine bark extract
No dietary source; available in supplement form.
Green tea
Green tea.
Quercetin
Onions, green tea, and red wine.
N-acetyl cysteine
No dietary source; available in supplement or drug form.
Turmeric
Turmeric is used as a spice.
Ellagic acid
Berries, pecans, walnuts, pomegranates.
Hesperidin
Citrus fruits. Oranges, tangelos, and lemons are the richest sources. Peel and pulp of fruit contain the highest amount.
Reishi mushroom
Reishi mushroom.

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