by Eileen Swee Lian Goh

Created on: March 08, 2009   Last Updated: October 29, 2010

FREE RADICAL THEORY OF AGING

Free radicals are believed to be the main culprits in the aging process. Antioxidants, by targeting free radicals, act as members of the "police force" charged with eradicating free radicals and maintaining health.

ANTIOXIDANT VALUE OF FOODS

Currently, the ORAC (Oxygen Radical Absorbance Capacity) scale is the gold standard for measuring the antioxidant value of foods, and a daily intake of 3000 to 5000 ORAC units may help to delay aging.

TYPES OF ANTIOXIDANTS

Many substances have been found to possess antioxidant properties, including:-

1. Vitamins -

a) Vitamin A and its precursors (that is, the carotenoids such as lutein, alpha- and beta-carotenes and lycopene);

b) Vitamin C or ascorbic acid; and

c) Vitamin E (tocopherols and tocotrienols).

2. Minerals - copper, zinc, manganese and selenium.

3. Flavonoids and isoflavonoids.

4. Polyphenols.

5. Thiols, in particular, glutathoine.

BEST SOURCES OF ANTIOXIDANTS

High levels of antioxidants can be found in both plant and animal products.

(A) Plant sources.

1. Fruits:-

a) "Berries" - blueberries (both wild and cultivated), blackberries, strawberries, raspberries, cranberries, acai berries, cherries, blackcurrants, grapes (black and red) and grape products (raisins and red wine);

b) Brightly colored fruits - squash, pumpkins, watermelons, oranges, lemons, papaya, apricots, mangoes, plums, pomegranates, pink grapefruit, avocados, nectarines and pineapples;

c) Others - apples (Red Delicious, Granny Smith and Gala) and prunes.

2. Vegetables:-

a) Dark leafy greens, such as spinach, lettuce and chard;

b) Brightly colored vegetables, such as carrots, tomatoes, orange and bell peppers, beets and eggplants;

c) Cruciferous vegetables, such as cabbage, cauliflower, broccoli, kale, turnip, brussels sprouts, alfalfa sprouts, radish and watercress;

d) Starchy vegetables, in particulr, potatoes (Russet and purple);

e) Bulb vegetables, such as leeks, garlic and onions;

f) Herbs, such as ginger, thyme, oregano and parsley.

3. Legumes:-

a) Nuts, especially, walnuts, almonds, pecans, hazelnuts and gingko;

b) Beans, such as red kidney and pinto beans, red and black beans as well as soya beans and soya products such as tofu;

c) Peas and lentils.

4. Seeds, especially, sesame, sunflower and lotus seeds.

5. Cereals:-

a) Wholegrains, such as brown rice, wholemeal bread, barley and oats.

b) Other cereal products - bran and wheat germ.

6. Spices such as cloves and cinnamon.

7. Teas (green, white, black and red).

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