Scientists not yet sold on 'super vitamins,' but are intrigued by early research


September 13, 1994|By Dr. Genevieve Matanoski | Dr. Genevieve Matanoski,Medical Tribune News Service

From a health and nutrition standpoint, the singular role of vitamins has been recognized for several generations. Through the pioneering work of Dr. E.V. McCollum of the Johns Hopkins School of Public Health, discoverer of vitamins A and D, the relationship between nutritional deficiencies and clinical symptoms of disease was demonstrated. Largely as a result of his untiring efforts, profound positive changes occurred in the American diet.

Recently, a particular group of vitamins called antioxidants has gained widespread attention. Looked upon as "super vitamins" in some circles, antioxidants have been credited with preventing everything from cataracts to cancer.

Unfortunately, inaccurate and trumped-up claims have produced misleading information and misunderstandings concerning an intriguing subject that scientists continue to explore.

For the latest information on antioxidants, I consulted Dr. Benjamin Caballero, director of the Center of Human Nutrition at the Johns Hopkins School of Public Health.

Q: What are antioxidants?

A: Antioxidants are nutrients -- particularly vitamins C, E and beta carotene -- that combat the toxic forms of oxygen that normally attack cells.

The problem originates with unstable oxygen molecules, known as free radicals, that are routinely produced by the human body. The molecules can kill dangerous microbes, but they also react with protein, DNA or the fatty parts of cell membranes to produce additional, destructive free radicals.

Over time, disease can result. Free-radical damage has been linked to cancer, heart disease, Parkinson's disease, cataracts and now, with the harmful effects of aging.

The damaging process is called oxidation. When cells, composed of fat and protein, come into contact with oxygen, they are quickly oxidized, or chemically altered, and damage results. The human body protects itself by using antioxidants and other mechanisms to correct damage done by free radicals and tohelp avoid further oxidation.

Q: How may antioxidants function in preventing disease?

A: Antioxidants neutralize or "sponge up" free radicals through an active "scavenge" or search. Scientists now suspect that complex antioxidant mechanisms can prevent some chronic diseases.

Under investigation is vitamin E's relationship to heart disease. Some studies have suggested that this antioxidant makes circulating low-density lipoproteins (LDL) less prone to oxidation, thereby preventing LDL buildup in arteries and consequent atherosclerosis. Antioxidants also may block the chain reaction that occurs when free radicals attack DNA, the genetic material of cells, resulting in mutations and possible cancer.

Research continues to try to determine whether antioxidants may help prevent cataracts, a condition where proteins in the lens of the eye are oxidized by free radicals, producing clouding. Perhaps most intriguing is the possible role antioxidants may play in the aging process, where tissue deterioration is linked to oxidation. Antioxidants may not make you live longer, but they may give you a healthier, more enjoyable life.

With research just beginning to yield more answers to these issues, the potential health benefits of antioxidants continue to expand. Significant work remains to be done to achieve a fuller understanding of the antioxidant impact on health.

Q: What are some sources of antioxidant-rich food?

A: Look for antioxidants in leafy green, yellow, orange and red vegetables (such as sweet potatoes, carrots and spinach); various fruits (fresh or frozen, not canned); and nuts and berries (such as strawberries, sunflower seeds and walnuts). Using established dietary guidelines of at least two servings of fruit and three servings of vegetables daily, people can derive an adequate amount of most antioxidants from food.

Dr. Matanoski is a physician and epidemiologist at the Johns Hopkins School of Hygiene and Public Health. She is founding director of its Institute for Women's Health Research and Policy.

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