The antioxidant vitamins are vitamin E, vitamin C, and the beta carotene form of vitamin A. Minerals such as selenium, copper, manganese and zinc also have antioxidant properties when combined with certain enzymes. There are many other antioxidant compounds in food, such as bioflavonoids found in fruit and vegetables; coenzyme Q10 found in fish, nuts and lean meats; and sulfur-containing amino acids.

Antioxidants and disease prevention

An antioxidant is a substance which gives up electrons easily so it can neutralize oxidants, including free radicals. Unfortunately, these protective systems may not always be adequate when the system becomes overloaded with free radicals.

When the antioxidant systems of the body are overwhelmed, free radicals stabilize themselves by stealing electrons from chemically stable compounds, often causing the generation of more free radicals which react further with other compounds, causing yet more damage. These split second chain reactions spread throughout the body, attacking vulnerable sites in the cells and causing damage that can result in chronic disease.

Free radicals can be produced in dangerous amounts by irritants such as cigarette smoke, pesticides, air pollution, ultraviolet light and radiation which are all too common in the environments in which most of us live. Stress and excessive exercise can also produce large amounts of free radicals.

Vitamins may exert their antioxidant effects by acting as circuit breakers. They insert themselves into the free radical chain reaction and are altered without generating further free radicals. Antioxidants interact to protect each other. Vitamin C can react with a damaged vitamin E molecule and convert it back to its antioxidant form. Vitamin C is then returned to its original form by another antioxidant known as glutathione. This may explain the result of studies which show that vitamin C enhances the protective effects of vitamin E.

Growing evidence strongly suggests that they have the power to prevent diseases such as cancer, coronary heart disease and cataracts. Studies show that diets high in antioxidants or antioxidant supplements reduce cancer death rates, cold and flu infections and protect against atherosclerosis, heart disease and cataracts. These vitamins may improve immune system function and may even delay some of the effects of aging. This is probably due to their ability to intercept and extinguish free radicals.

Free radicals

Oxygen, the most critical nutrient for life, is the main source of free radicals, which could be the fundamental cause of many chronic diseases and even of the aging process. Free radicals are highly reactive oxygen fragments which are created by normal chemical processes in the cells. They lack electrons and try to steal them from other molecules to regain balance, a process known as oxidation. Free radicals include the superoxide radical, the hydroxyl radical and hydrogen peroxide.

A certain level of free radicals is essential for good health as they are involved in fighting infection and in the contraction of smooth muscles in the blood vessels. Cells have a number of ways of dealing with excess free radicals including the use of enzyme systems and specific antioxidants.