Without antioxidants, many of us would be prey to numerous infections and possibly even cancer within a few months. Although our bodies produce their own antioxidants, we also need to boost our defences by eating foods that contain them. Just how important these dietary antioxidants are is a matter of great debate. All too often claims for dietary antioxidants, particularly for supplements, have been exaggerated, but recent research suggests that they may offer protection against certain cancers and heart disease, and may also help to prevent premature ageing.
Antioxidants protect against free radicals, chemicals which are formed in the body as part of its metabolism and defence against bacteria. Certain factors, such as excessive exposure to environmental pollution or ultraviolet light, illness and cigarette smoke, can cause the body to increase its production of free radicals. Left unchecked, these unstable and potentially harmful chemicals create conditions that may precipitate heart disease and cancer. To cope with these free radicals, the body needs more antioxidants than it can produce, particulary during times of illness or when exposed to pollutants. Fortunately, many foods provide antioxidants that help to protect the body against their threat.
Vitamins E and C and beta carotene, the plant form of vitamin A, help to neutralise free radicals, as do minerals such as selenium, (found in shellfish and avocados), copper (in nuts, seeds and shellfish) and zinc (in shellfish). Bioflavonoids, found in some fruit and vegetables, including citrus fruits, and grapes, also have antioxidant properties. Artificial antioxidants are added to margarine and oils to stop them becoming rancid, and to retain the natural colourings of processed foods.
More research is needed into the role of antioxidants in disease prevention. However, it is thought that free radicals may start the damage that causes fatty cholesterol deposits in the arteries, which can eventually lead to heart disease or stroke. High levels of antioxidant vitamins and minerals may help to prevent this harmful process, as well as damage to DNA that could lead to certain cancers.
Supplements of particular antioxidant vitamins or minerals need to be taken in the correct balance and, even then, too many can be harmful. To obtain an adequate intake of antioxidants, it is safer to eat plenty of fresh fruit and vegetables. Citrus fruit provides vitamin C, and brightly coloured fruit and vegetables supply beta carotene. The vitamin E found in nuts, avocados and vegetable oils may also help to protect against disease.