De-mystifying Antioxidants

We hear a lot about antioxidants and how they are good for us. It seems like every food today contains this mysterious element, even chocolate. But what is an antioxidant and how can all these foods contain this one substance? After all, if you look at a food label you won’t find “antioxidants” listed in the ingredients. That’s because antioxidants come in many different forms as vitamins, minerals, polyphenols and flavonoids.

An antioxidant is a substance that protects cells from free radicals, which are by-products of oxygen metabolism that contribute to tissue damage in the body and may contribute to the development of heart disease, cancer, stroke and other diseases. For example, when low-density lipoprotein (LDL) cholesterol is oxidized, it can become glued to arteries and cause coronary heart disease.

Vitamins and Minerals
Antioxidant substances include beta-carotene; lutein; lycopene; vitamins A, C, and E; selenium; and zinc. These antioxidants are found in many foods which include fruits and vegetables, nuts, grains, and some meats, poultry and fish.

Polyphenols are a chemical that act as antioxidants, protecting cells from tissue damage, but can also block the action of enzymes that cancers need for growth and they can deactivate substances that promote the growth of cancers. The polyphenol most strongly associated with cancer prevention is epigallocatechin-3-gallate, or EGCG, found highest in green tea but also grape seeds and cocoa.

Polyphenols occur in all plant foods and can contribute up to 10 times more antioxidant capacity than that of vitamins. For example, the total intake of polyphenols in a person’s diet could amount to 1 gram a day, whereas combined intakes of beta-carotene, vitamin C, and vitamin E from food is often about 100 mg a day (1/10 that that of polyphenols).

One third of the total intake of polyphenols in our diet comes from phenolic acids and the remaining two thirds comes from flavonoids which are further subdivided into several categories with over 6000 different types.

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