What are Antioxidants? Antioxidant Definition
It is not possible to give a simple antioxidant definition but it can be explained as below.
What are Antioxidants? | Antioxidant benefits | Antioxidants Foods | Antioxidants In Tea
As free radicals (see below) have deficiency of electrons, compounds are needed which can neutralize free radicals by donating their own electrons to free radicals but they themselves do not become free radicals in the process. This stops the electron-"stealing" chain reaction.
The antioxidants themselves do not become free radicals by donating an electron because they are stable in either form. They convert free radicals to harmless waste products that are eliminated from the body before any damage is done to the body.
Thus the antioxidants act as scavengers, helping to prevent cell and tissue damage.
The antioxidants are very good for prevention of diseases like heart disease and cancers. The vitamin E may protect against cardiovascular disease by defending against plaque formation in the arteries.
The vitamin C defend against cancers of the mouth, larynx and esophagus.
What are Free Radicals?
In a molecule, atoms are bound together by sharing electrons with other atoms. When weak bonds split, free radicals are formed.
A free radical is a molecule with one electron missing. These free radicals are very unstable and attack the nearest stable molecules to get electrons. This results in a chain reaction and new free radicals are formed.
What Produces Free radicals?
Free radicals are formed in the body due to several reasons. Some are given below.
- Burning of oxygen by body's cells to produce energy.
- Environmental factors such as pollution, smoking, cigarette smoke, alcohol, stress, herbicides, radiation and ultraviolet light.
- During metabolism.
- Sometimes the body's immune system create them to neutralize viruses and bacteria.
Free Radical Damage
Normally the body can handle these free radicals, but excessive free radicals can damage cells and are not good for health.
If the free radicals take electrons from important components in the body, like protein, fat or DNA, they create health problems such as cataract, heart disease, arthritis, aging and cancer. Free radicals can also contribute to premature aging.
Natural antioxidant food list include fruits, vegetables, cereals, legumes, nuts and seeds. The best way to ensure adequate intake of the antioxidants is to eat a variety of fruits and vegetables through a diet consisting of 5 to 8 servings of fruits and vegetables per day.
Scientists as reported at the 238th National Meeting of the American Chemical Society in Aug 2009 have found that some vegetables and fruits like berries, grapes, walnuts, olives, and foods like chocolate, wine, coffee, tea and popcorn, and some breakfast cereals contain large amounts of healthful antioxidant substances called polyphenols.
Polyphenols play important role in reducing the risk of heart disease, cancer and other diseases.
FruitsBerries (Cherry, blackberry, strawberry, raspberry, crowberry, blueberry, bilberry/wild blueberry, black currant), mulberry, pomegranate, grape, orange, plum, pineapple, kiwi fruit, grapefruit, guava. The longan fruit is termed as a Superfood due to its antioxidant and other benefits (Health benefits of Longan Fruit)
Antioxidant concentrations in some fruits are: about 500 mg per 100 g in guavas, 330 mg in plums, 170 mg in mangoes, 135 mg in pomegranates, 125mg in apples and 30 mg in bananas. Watermelons and pineapples offer the least protection for the body's fight against free radicals, according to Dr Sreeramulu reported in the Telegraph (2012). The study found that guavas are the ultimate super food with the highest concentration of antioxidants.
VegetablesKale, chili pepper, red cabbage, peppers, parsley, artichoke, Brussels sprouts, spinach, lemon, ginger, red beets are antioxidant rich.
LegumesBroad beans, pinto beans, soybeans are antioxidants sources.
Nuts and seedsPecans, walnuts, hazelnuts, ground nut or peanuts, sunflower seeds contain good amount of antioxidants.
Roasted peanuts are far richer in antioxidants than apples, beets and carrots and comparable to the antioxidant content of strawberries and blackberries.
Peanuts contain high concentrations of antioxidant polyphenols, roasting boosts its overall antioxidant content by as much as 22 per cent. Roasted peanuts are far richer in antioxidants than apples, beets and carrots and comparable to the antioxidant content of strawberries and blackberries.
CerealsBarley, millet, oats, corn are rich in antioxidants.
Spicescloves, cinnamon, oregano
All foods are not equally good if we consider their antioxidant content. Some are better than the others in their antioxidant capability. USDA recommends top 20 best sources of food antioxidants as measured by their total antioxidant capacity per serving size. These foods provide more antioxidant power than antioxidant vitamins and supplement. The antioxidant content of top 20 antioxidant foods are given below.
In the table below, the list is given according to their antioxidant power per their serving sizes.
Scientists at the USDA have developed a rating scale that measures the antioxidant content of various natural plant foods. The scale is called ORAC, which stands for Oxygen Radical Absorbance Capacity.
USDA recommends to eat foods containing at least 3,000 ORAC units a day.
Growing organic blueberries
Antioxidants In Tea
All teas are an extremely rich source of antioxidants. Tea has approximately ten times the amount of antioxidants found in fruits and vegetables. But fruits and vegetables have other important nutrients.
All teas - oolong tea, black tea and green tea all come from antioxidant rich plant called Camellia sinensis. All teas contain the same amount of antioxidants, the main difference lies in the way they are processed. While green tea is wilted and steamed, oolong and black teas are processed by fermenting and crushing.
It should be noted that adding milk to tea does not affect the antioxidant absorption in the body .
- C. Vijayakumar et. al., Addition of Milk Does Not Alter the Antioxidant Activity of Black Tea, Annals of Nutrition and Metabolism, Vol. 49 (2005).
- Benzie, I; Evolution of dietary antioxidants, Comparative Biochemistry and Physiology 136 (1), 113-26 (2003)
- Thomas D, Vitamins in health and aging, Clin Geriatr Med 20 (2), 259-74 (2004)
- Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, 2007, the United States Department of Agriculture, http://www.ars.usda.gov/SP2UserFiles/Place/12354500/Data/ORAC/ORAC07.pdf