Ounce for ounce, many herbs used to flavor foods have more antioxidant power than berries, fruits and vegetables, according to a recent Agricultural Research Service study.
Previous studies of animals and of human blood have shown that foods that score high in antioxidant capacity may protect cells and their components from oxidative damage. The thesis that oxidative damage culminates in many of the maladies of aging is well accepted in the health community.
Herbs are known to be good sources of antioxidants, but their potency can vary depending on species and growing conditions. So, researchers, at the ARS Fruit Laboratory, in Beltsville, MD, evaluated a variety of fresh culinary and medicinal herbs grown under the same environmental conditions at the same location, the ARS National Arboretum, in Washington DC.
ARS plant physiologist Shiow Wang and visiting scientist Wei Zheng, from the Institute of Environmental Science, in Zhejing, China, put 27 culinary herbs and 12 medicinal herbs to the antioxidant test. Known as ORAC for short, the test measures the ability of a sample to disarm oxidizing compounds, which our bodies naturally generate as a byproduct of metabolism.
Three different types of oregano--Mexican, Italian and Greek mountain--scored highest in antioxidant activity. Their activity was stronger than that of vitamin E and comparable to the food preservative BHA against fat oxidation, the researchers reported in the November, 2001, issue of the Journal of Agricultural and Food Chemistry.
Several other culinary herbs--among them rose geranium, sweet bay, dill, purple amaranth and winter savory--also showed strong antioxidant activity. But it was about one-half to one-third as potent as that of the oreganos. The medicinal herbs generally scored lower in antioxidant activity, suggesting that their health benefits mostly stem from other functions in the body.
According to Wang, antioxidant activity of these herbs may vary considerably, depending on where they are grown. But their rankings would tend to hold up in other environments, because of characteristic compounds in each species. The oreganos, for instance, had high levels of the potent antioxidant rosmarinic acid.
The highest scorer in this study, Mexican oregano (Poliomintha longiflora), is used in traditional Mexican and Southwest recipes. Its flavor is a bit stronger than Italian oregano (Origanum x majoricum), used to season meats, egg dishes, soups and vegetables. Greek mountain oregano (Origanum vulgare ssp.hirtum), had the third highest score.
ARS is the chief scientific research agency of the U.S. Department of Agriculture.