'NATURAL' VITAMINS HAVE MORE ANTIOXIDANTS THAN MAN-MADE

DALLAS-While vitamin supplements are more popular than ever, the public should know that some have more antioxidant properties than others, researchers said here this week at the annual meeting of the American Chemical Society.

In particular, man-made vitamin supplements do not match the complex variety of natural antioxidants present in those derived from plant extracts, according to a report from Amway Corporation's Rehnborg Center for Nutrition and Wellness in Buena Park, Calif.

"While the Food and Drug Administration's definition of antioxidants is limited to vitamins C, E and [the precursor of vitamin A], beta-carotene we take a broader approach to antioxidant research," said Amway biochemist Yong Qian, Ph.D. "Antioxidants from natural products are very diverse."

Qian compared the biochemical "profile" of a plant-derived nutritional supplement under development with that of a typical synthetic multivitamin pill. In addition to vitamins C, E and a single form of beta-carotene found in the multivitamin, the natural product-made from concentrated extracts of alfalfa, carrots and watercress-was found to contain several different antioxidant chemicals including lutein, several different forms of beta-carotene and some as-yet unidentified antioxidant compounds.

Qian and coworkers used a crude test to identify individual antioxidants, chemicals thought to protect cells from the toxic effects of free radicals, which have been implicated in a variety of age-associated disorders and cancer.

Various plant-derived vitamin supplements are currently available in health-food stores.

Natural antioxidants can be divided into three basic types, each of which acts to protect a different part of the cell, Qian explained. Water-soluble compounds such as vitamin C guard cells' interiors, while fat-soluble antioxidants like vitamin E and beta-carotene enter cell membranes. A third class of antioxidants found in plant extracts-but generally not in synthetic vitamins - is located on membrane surfaces.

"We think all three types of antioxidants are important for good health," Qian said. The limited range of antioxidants in synthetic vitamins, "can't cover all the functions that natural antioxidants potentially perform," he added. Thus, he and his coworkers hope to identify and purify a variety of natural antioxidant compounds to enhance the company's nutritional supplements.

The Amway scientists are hardly alone in their search for natural antioxidants. Scientists at several companies, and also in some academic laboratories, are studying a broad spectrum of plant-derived chemicals that may extend the apparent benefits of vitamins A, C and E, said Youling Xiong, an associate professor of food science at the University of Kentucky in Lexington.

"I think this is a valuable area of research," he said. But, he added, screening plant extracts for antioxidant activity as Qian described is only the first step in the process of identifying useful compounds.

"It's a classic test of antioxidant activity, but it doesn't tell you anything about how animals [bodies use] these chemicals," Xiong explained. More sophisticated tests would be required to demonstrate that potential antioxidants would retain their potency after ingestion.

However, the fact that humans have eaten fruits and vegetables for millions of years raises hopes that additional plant-derived compounds will prove beneficial. "We co-evolved with these natural sources of nutrients, so we think we can use them efficiently, " Xiong said.

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