But the scale used in the book to determine antioxidant levels is not perfect, the author admits, and antioxidant research is, relatively speaking, still in its infancy.

We asked the experts to explain antioxidants and how we should approach measuring their health effects.

What are antioxidants?

Antioxidants are compounds that prevent free radicals from damaging the cells of your body. The damage, called oxidative stress, can accumulate and lead to several chronic diseases, including cardiovascular disease and cancer, as well as age-related conditions, such as macular degeneration, said researcher Diane McKay.

RANKING THEM

To rank foods, Glassman used something called the Oxygen Radical Absorbance Capacity (ORAC) scale, which was developed in the early 1990s and refined by the U.S. Department of Agriculture. The ORAC scale is one of several methods used to measure how well a food protects against disease-causing free radicals.

Phytochemicals, which are found in all plant-based foods, including fruits, vegetables, whole grains, beans, legumes, nuts, seeds, cocoa, teas and wine, all have antioxidant activity. Artichokes, for example, score 7,900 ORAC points. A sweet potato provides 2,400 ORAC points, while broccoli adds 600.

THE CATCH

Though berries, nuts and teas often top lists that measure antioxidant activity, "it's very misleading for food/beverage manufacturers to state the ORAC value of their product on the label and in advertisements, as this information has little relevance to the health effects of these products," said McKay, a researcher at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.

The problem, McKay said, is that even if a food or beverage ranks higher than others, it doesn't necessarily mean, for example, that it will increase the antioxidant capacity of your cells.

"Some antioxidant-rich foods will increase the body's antioxidant capacity after you eat them, but others do not," she said.

One reason might be that other compounds in the food can affect how your body absorbs the phytochemicals or other antioxidant micronutrients, McKay said.

Another point to remember: More of a single nutrient is not necessarily better. Some studies have showed negative effects when antioxidants are administered in high amounts, particularly in the presence of certain minerals, said McKay.

THE BOTTOM LINE

"Just because a food or beverage scores well with the ORAC test doesn't guarantee that it can cure, treat or even prevent disease," McKay said. "However, most of the foods or beverages that have been studied for their health effects are those that have high antioxidant activity — teas, wine, cocoa, etc. The data certainly suggest that incorporating these antioxidant-rich foods and beverages into our regular diet, in moderate amounts, may help improve some biomarkers of disease risk."

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(c) 2010, Chicago Tribune.