You've heard that you can't compare apples to oranges. But a biochemist in the American Journal of Agricultural and Food Chemistry (Vol. 49, No. 11: 5165-5170) compared apples to oregano with some pretty interesting results.

For instance, a tablespoon of fresh oregano packs the same antioxidant punch as an apple, said Shiow Y. Wang, PhD, a researcher at the USDA's Beltsville Agricultural Research Center in Beltsville, Md. In her study, Wang found that some fresh herbs have higher antioxidant activity than fruits, vegetables, and many spices, including garlic.

Antioxidants are often mentioned when talking about diet and health. They are a class of compounds thought to prevent certain types of damage to cells in the body caused by free radicals.

Free radicals are charged molecules that are constantly generated in the body as a result of normal metabolism. Researchers believe destroying free radicals may help prevent cancer, heart disease and stroke.

The herbs in the oregano family had the highest antioxidant activity. In general, oregano had three to 20 times more than the other herbs studied.

Gram for gram, oregano and other fresh herbs ranked even higher than fruits and vegetables that are known to be high in antioxidants. And oregano ranks supreme: it has 42 more times antioxidant activity than apples, 30 times more than potatoes, and 12 times more than oranges.

"People should use more herbs for flavoring instead of salt and artificial chemicals," said Wang.

Adding a moderate amount of fresh herbs may go a long way toward boosting the health value of a meal, the researchers said. And even if oregano is not a favorite, other herbs also have antioxidant effects. Among the more familiar, in order, are dill, garden thyme, rosemary and peppermint.

In general, fresh herbs and spices are healthier and contain a higher level of antioxidant activity than dried or processed counterparts. Garlic is a good example — fresh garlic is one and a half times more powerful than dry garlic powder.

Wang and colleagues looked at 39 herbs grown in the same location, under the same conditions. The study included 27 culinary (used in cooking) and 12 medicinal herbs.

In general, culinary herbs had more antioxidant activity than the medicinal herbs, such as feverfew. The most active ingredient in the herbs with the highest antioxidant activity was rosmarinic acid, a strong antioxidant, said the researchers.

And when Wang compared the antioxidant activity of herbs to spices, including paprika, garlic, curry, chili, and black pepper, the herbs came out on top, she said.

Fruits and vegetables have long been seen as a rich source of antioxidants. While consumers have been urged for years to eat more fruits and vegetables, progress is slow, said the researchers. Westerners still favor diets high in fats and carbohydrates.

Researchers have recently begun formal study of the health benefits of herbs and spices. The difference between herbs and spices is mainly where they come from. Herbs are usually from plant leaves, and spices are usually made from the bark, stem, and seeds.

Now herbs may be emerging as a quick and easy way to get a concentrated source of antioxidants, without all the calories of whole foods, Wang said. But herbs are no substitute for a balanced diet. Just as consuming too much of any food product can carry health risks, herbs should be used in moderation.

Pregnant women in particular should talk with their doctors before taking herbal supplements, said Wang.