Antioxidants:
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Antioxidants are substances or nutrients in our foods which can prevent or slow the oxidative damage to our body. When our body cells use oxygen, they naturally produce free radicals (by-products) which can cause damage. Antioxidants act as "free radical scavengers" and hence prevent and repair damage done by these free radicals. Health problems such as heart disease, macular degeneration, diabetes, cancer etc are all contributed by oxidative damage. Indeed, a recent study conducted by researchers from London found that 5 servings of fruits and vegetables reduce the risk of stroke by 25 percent. Antioxidants may also enhance immune defence and therefore lower the risk of cancer and infection.
Beta-carotene
Beta-carotene is a substance from plants that the body converts into vitamin A. It also acts as an antioxidant and an immune system booster.
Other members of the antioxidant carotenoid family include cryptoxanthin, alpha-carotene, zeaxanthin, lutein, and lycopene. However, unlike beta-carotene, most of these nutrients are not converted to vitamin A in significant amounts.
Where is it found?
Dark green and orange-yellow vegetables are good sources of beta-carotene. It is also available in supplements.
Who is likely to be deficient?
People who limit their consumption of beta-carotene-containing vegetables could be at higher risk of developing a vitamin A deficiency. However, because beta-carotene is not an essential nutrient, true deficiencies do not occur. Nevertheless, very old persons with type 2 diabetes have shown a significant age-related decline in blood levels of carotenoids, irrespective of their dietary intake.
Alpha lipoic acid
Alpha lipoic acid (ALA) is a vitamin-like antioxidant, sometimes referred to as the “universal antioxidant” because it is soluble in both fat and water.1 ALA is manufactured in the body and is found in some foods, particularly liver and yeast.
ALA is capable of regenerating several other antioxidants back to their active states, including vitamin C, vitamin E, glutathione and coenzyme Q10.
ALA has several potential benefits for people with diabetes. It enhances glucose uptake in type 2 (adult onset or non-insulin-dependent) diabetes, inhibits glycosylation (the abnormal attachment of sugar to protein), and has been used to improve diabetic nerve damage and reduce pain associated with that nerve damage. Most studies have used intravenous alpha lipoic acid, but oral supplementation has nonetheless proved partially helpful in treating at least one form of diabetic neuropathy, using 800 mg per day.
Preliminary evidence indicates that 150 mg of alpha lipoic acid, taken daily for one month, improves visual function in people with glaucoma.
ALA has been shown to inhibit the replication of the HIV virus in the test tube; however, it is not known whether supplementing with ALA would benefit HIV-infected people.
Intravenous administration of ALA has significantly increased the survival rate of people who have eaten poisonous mushrooms. Such a treatment should be prescribed by a doctor and should not be attempted on one’s own.
Where is it found?
The body makes small amounts of alpha lipoic acid. There is only limited knowledge about the food sources of this nutrient. However, foods that contain mitochondria (a specialized component of cells), such as red meats, are believed to provide the most alpha lipoic acid. Supplements are also available.
Lutein
Lutein is an antioxidant in the carotenoid family (a group of naturally occurring fat-soluble pigments found in plants). Lutein is the primary carotenoid present in the central area of the retina called the macula.
Lutein may act as a filter to protect the macula from potentially damaging forms of light. Consequently, lutein appears to be associated with protection from age-related macular degeneration (the leading cause of blindness in older adults).
Where is it found?
Spinach, kale, collard greens, romaine lettuce, leeks, peas, and egg yolks are good sources of lutein.
Who is likely to be deficient?
While a deficiency has not been identified, people who eat more lutein-containing foods appear to be at lower risk of macular degeneration. One study found that adults with the highest dietary intake of lutein had a 57% decreased risk of macular degeneration compared with those people with the lowest intake, and of the carotenoids, lutein and zeaxanthin are most strongly associated with this protection. In a preliminary study, a similar link was suggested between low dietary lutein and increased risk of cataracts.
Vitamin A
Vitamin A is a fat-soluble vitamin with four major functions in the body: It helps cells reproduce normally—a process called differentiation (cells that have not properly differentiated are more likely to undergo pre-cancerous changes). It is required for vision; vitamin A maintains healthy cells in various structures of the eye and is required for the transduction of light into nerve signals in the retina. It is required for normal growth and development of the embryo and foetus, influencing genes that determine the sequential development of organs in embryonic development. It may be required for normal reproductive function, with influences on the function and development of sperm, ovaries and placenta.
For some people, water-soluble forms of vitamin A supplements appear to be better absorbed than fat-soluble vitamin A.
Who is likely to be deficient?
People who limit their consumption of liver, dairy foods, and beta-carotene-containing vegetables can develop a vitamin A deficiency. Extremely low birth weight babies (2.2 pounds or less) are at high risk of being born with a deficiency, and vitamin A shots given to these infants have been reported in double-blind research to reduce the risk of lung disease. The earliest deficiency sign is poor night vision. Deficiency symptoms can also include dry skin, increased risk of infections, and metaplasia (a precancerous condition). Severe deficiencies causing blindness are extremely rare in Western societies.
Less severe deficiencies are more likely to occur with a variety of conditions causing malabsorption. A high incidence of vitamin A deficiency in people infected with HIV has also been reported. People with hypothyroidism have an impaired ability to convert beta-carotene to vitamin A. For this reason, some doctors suggest taking supplemental vitamin A (perhaps 5,000–10,000 IU per day) if they are not consuming adequate amounts in their diet.
Very old people with type 2 diabetes have shown a significant age-related decline in blood levels of vitamin A, irrespective of their dietary intake.
Vitamin D
The fat-soluble vitamin D’s most important role is maintaining blood levels of calcium, which it accomplishes by increasing absorption of calcium from food and reducing urinary calcium loss. Both effects keep calcium in the body and therefore spare the calcium that is stored in bones. When necessary, vitamin D transfers calcium from the bone into the bloodstream, which does not benefit bones. Although the overall effect of vitamin D on the bones is complicated, some vitamin D is necessary for healthy bones and teeth.
Vitamin D plays a role in immunity and blood cell formation and also helps cells "differentiate"—a process that may reduce the risk of cancer. From animal and human studies, researchers have hypothesized that vitamin D may protect people from multiple sclerosis, auto-immune arthritis, and juvenile diabetes.
Vitamin D is also needed for adequate blood levels of insulin. Vitamin D receptors have been found in the pancreas where insulin is made, and preliminary evidence suggests that supplementation may increase insulin secretion for some people with adult-onset (type 2) diabetes.
Where is it found?
Cod liver oil is an excellent dietary source of vitamin D, as are vitamin D-fortified foods. Traces of vitamin D are found in egg yolks and butter. However, the majority of vitamin D in the body is created during a chemical reaction that starts with sunlight exposure to the skin. Cholecalciferol (vitamin D3) is the animal form of this vitamin.
Pycnogenol®
Pycnogenol® is the patented trade name for a water extract of the bark of the French maritime pine ( Pinus pinaster ssp. atlantica ), which is grown in coastal south-west France. Pycnogenol® contains oligomeric proanthocyanidins (OPCs) as well as several other bioflavonoids: catechin, epicatechin, phenolic fruit acids (such as ferulic acid and caffeic acid), and taxifolin. Procyanidins are oligometric catechins found at high concentrations in red wine, grapes, cocoa, cranberries, apples, and some supplements such as Pycnogenol®.
One of its main ingredients of Pycnogenol® is proanthocyanidin, which has a similar structure to bioflavonoids and is a powerful antioxidant. As such it helps to mop up harmful free radicals in the body. It's an immune-system booster and helps to strengthen blood vessel walls and capillaries. It has an especially beneficial effect on lung tissue.
Therapeutic uses: recommended for people with respiratory problems, such as asthma and bronchitis, poor circulation, menstrual cramps, haemorrhoids and hypertension. As it also protects collagen, it can be used to hinder the onset of wrinkles and maintain skin elasticity.
Grape Seed Extract
Proanthocyanidins—also called "OPCs" for oligomeric procyanidins or "PCOs" for procyanidolic oligomers—are a class of nutrients belonging to the flavonoid family.
Proanthocyanidins have antioxidant activity and they play a role in the stabilization of collagen and maintenance of elastin—two critical proteins in connective tissue that support organs, joints, blood vessels, and muscle.1 2 Possibly because of their effects on blood vessels, proanthocyanidins have been reported in double-blind research to reduce the duration of oedema after face-lift surgery from 15.8 to 11.4 days.3 In preliminary research, proanthocyanidins were reported to have anti-mutagenic activity (i.e., to prevent chromosomal mutations).4
Proanthocyanidins have been shown to strengthen capillaries in double-blind research using as little as 100 mg per day.5 In another double-blind trial, French researchers reported that women with chronic venous insufficiency had reduced symptoms using 150 mg per day.6 In another French double-blind trial, supplementation with 100 mg taken three times per day, resulted in benefits within four weeks.7
Proanthocyanidins (200 mg per day for five weeks) have improved aspects of vision (visual performance in the dark and after exposure to glare) in healthy people.8 9 A product that is high in proanthocyanidins has been shown to prevent and reverse abnormal blood clotting in smokers.10
Where are they found?
Proanthocyanidins can be found in many plants, most notably pine bark, grape seed, and grape skin. However, bilberry, cranberry, black currant, green tea, black tea, and other plants also contain these flavonoids. Nutritional supplements containing proanthocyanidins extracts from various plant sources are available, alone or in combination with other nutrients, in herbal extracts, capsules, and tablets.
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