The term 'antioxidants' has become part of modern speech, but it may be a good idea to dwell on what we mean by it, and what antioxidants really do.

Definition
According to Krause' Food, Nutrition & Diet Therapy (2000), antioxidants are "substances that can inhibit reactions of free radicals such as reactive species of oxygen; used to describe vitamins C and E, some carotenoids, ubiquinones and bioflavonoids".

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What this means in everyday languages is that antioxidants are compounds, such as vitamins C and E, that can stop the reactions of dangerous free radicals in the body.

Free radicals are formed both during normal metabolism, and whenever the body is exposed to stresses such as pollutants in the air (cigarette smoke), food (trans-fats), water (heavy metals), and even excessive exercise. Left unchecked, these free radicals cause extensive damage to the cells of the body and are believed to play a role in the development of degenerative diseases such as heart disease, cancer and arthritis.

If you can imagine the cells of the human body being exposed to attack by armies of free radicals that will damage or kill the body cells if they get a chance, then antioxidants are part of an opposing army that comes to the defence of the body, making free radicals harmless and preventing them from attacking our cells.

Example
To illustrate the effect of free radicals and the counter-reaction of antioxidants, we can use heart disease as an example.

Scientists have identified so-called LDL-cholesterol ("bad" cholesterol) as one of the harmful components in blood that promotes the development of heart disease.

The more negative stresses the body is exposed to (cigarette smoking, trans-fatty acids, high-fat diets), the more LDL-cholesterol is formed and the more serious the deterioration of the linings of the blood vessels will become, ultimately leading to heart disease.

Ensuring that our diets are rich in antioxidants (vitamins C and E, beta-carotene and bioflavonoids), is one way in which we counter the negative effects of LDL-cholesterol.

Antioxidants and exercise
Most readers may be surprised to hear that something as beneficial as exercise also increases the quantities of harmful free radicals produced in the body.

If we keep in mind that free radicals are always formed when oxidation occurs in the body, it is understandable that when rapid and wide-spread oxidation occurs during exercise (when muscles are working hard), the body produces more waste products of oxidation, namely free radicals.

These free radicals will also be neutralised by antioxidants, which is why athletes need to ensure that they have adequate intakes of vitamins C and E, carotenoids and other antioxidants.

Taking antioxidants such as vitamins C and E or beta-carotene, probably also improve recovery after exhaustive exercise.

However, more of a good thing is not always better. The National Academy of Sciences in the USA has recommended that athletes do not exceed the RDA for vitamins and minerals, but should rather stick to the daily requirements when planning increased intakes.

Check the vitamin supplements you use and make sure that you are not taking more than 1 x the RDA for each vitamin and mineral.

Dietary sources of antioxidants
While certain individuals who are exposed to stresses of growth, illness or exposure to pollutants, may benefit from taking antioxidant supplements, most people can obtain the antioxidants they require by eating a healthy, balanced diet that emphasises foods which are rich sources of antioxidants.

The following foods are rich in antioxidants:
Vitamin C:
All citrus fruits and citrus juices (oranges, grapefruit, naartjies, lemons, tangerine), cranberries, strawberries and other berry fruits, mango, pawpaw, spanspek, guava, kiwi fruit, all vegetables in the cabbage family (cabbage, kale, broccoli, Brussels sprouts, cauliflower), sweet peppers, chilli peppers, spinach, tomato and all tomato products.

Vitamin E
Wheat germ oil, all commercial oils (vitamin E is added to these oils as an antioxidant), nuts, avocado, mayonnaise, margarine.

Beta-carotene
All dark yellow (pumpkin, butternut, carrots, spanspek, pawpaw, apricot, mango, sweet potato) and dark green (broccoli, spinach, dark lettuce leaves) fruits and vegetables.

Ubiquinones (coenzyme Q)
Fish oil, nuts, fish and lean meat.

Bioflavonoids
All plant foods, wine, green and black tea.

It is evident from the above that eating five-a-day or more of fruits and vegetables is the best way to ensure that you obtain sufficient vitamin C, beta carotene and bioflavonoids. If you add wheat germ oil, other healthy oils such as olive or canola oil, avocado, nuts and fish plus good red wine and tea to your diet, you will also ensure adequate vitamin E and ubiquinone intake.

Stocking up on antioxidants is easy (many fruits and vegetables contain a variety of antioxidants, for example broccoli contains vitamin C, beta-carotene and bioflavonoids) and delicious. If you are exposed to additional stresses that may produce excessive free radicals, consider taking a vitamin and mineral supplement, but don't take more than the RDA for each nutrient.

Good health and protection against the ravages of free radicals are available to all of us, provided we use the bounty of nature on a daily basis. – (Dr Ingrid van Heerden, DietDoc)

Reference:
(Mahan LK, Escott-Stump, S (2000). Krause's Food, Nutrition & Diet Therapy. 10th Ed. WB Saunders Co.)

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