August 29, 1997

Popping vitamins may do more harm than good

You know the saying, too much of a good thing can kill you. In the case of some vitamins, too much can actually speed up the process.

That's the conclusion from the Sixth World Congress on Clinical Nutrition held in Banff this summer, the first time in North America.

More than 150 scientists, health professionals and doctors from around the world focused on anti-oxidants such as vitamins C, E, and beta carotene and their relationship to disease during the three-day conference, July 23-26.

Dr. Tapan Basu, a professor of nutritional biochemistry and chair of the Nutritional Congress, says lectures, symposia and posters revolved around the role of such vitamins in the prevention and treatment of disease, particularly coronary, cancer and cataract disease and rheumatoid arthritis.

Basu says while there is strong evidence linking anti-oxidants with decreasing cancer rates, there is still much to learn.

Too many people take arbitrary doses of vitamins, says Basu, and their effects over the long term are still not well documented. Clinical studies must be designed and proper dose levels have to be ascertained. "Anti-oxidants can actually be pro-oxidants if you don't watch the dosage levels," he says.

In other words, taking some vitamins to slow down the aging process and the breakdown of the body's cells can actually have the reverse effect if you take too many.

Basu says what is lacking is reliable methods to determine anti-oxidant activity levels. In addition, scientists do not know if anti-oxidants work individually or in combination with other food factors.

"In experiments using one anti-oxidant alone, like vitamin E or C, the results are negative. But, when combinations of anti-oxidants were used, the results were positive," says Basu.

Therefore, until scientists can determine healthy dosages and the right combination of anti-oxidants, stick to plenty of fresh fruits and vegetables in your diet, says Basu, and forget about popping mega-doses of vitamins.

U of A professors Dr. Catherine Field and Dr. Linda McCargar also spoke at the Congress. Field discussed the role of nutrition in the development of the immune system. McCargar spoke on the leptin response and body weight regulation in humans.

Basu, who was elected president of the International College of Nutrition, looked at the impact of niacin in humans, specifically niacin-induced hyperhomocysteinemia.

The University of Alberta and the International College of Nutrition, among other research and industry associations, sponsored the Sixth World Congress on Clinical Nutrition.

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