BOSTON—As most of us learned in school, fruit is delicious because it evolved to be eaten—if plants can entice animals to eat their seeds, they'll be spread far and wide in handy packets of fertilizer. But spices are different. Spices and herbs such as thyme, oregano, turmeric and cinnamon get their singular flavors from compounds that are actually toxic in concentrated doses—and plants probably evolved to express these toxins so their leaves and berries would not be eaten. So why do we humans cultivate them and put them all over our food? Nobody knows for sure, but as explained today in a presentation here at the annual meeting of the Association for Psychological Science, scientists are starting to discover a whole host of health benefits from common herbs and spices—and it's possible that we humans evolved a taste for these toxic compounds because they help our bodies function better.

Spices top the list of foods rich in antioxidants, explained Marianne Gillette, a vice president at McCormick & Company, whose background is in experimental taste research. One half teaspoon of ground cinnamon has as many antioxidants as a half cup of blueberries; a half teaspoon of dried oregano rivals three cups of raw spinach.

And the health benefits go far beyond antioxidants. A U.C.L.A. paper published May 9 in the American Journal of Clinical Nutrition found that adding a mixture of herbs and spices to hamburgers reduced the level of carcinogenic compounds created by grilling—such as the dangerous malondialdehyde that forms when beef fat oxidizes. Malondialdehyde damages DNA in cells, which is thought to lead to replication errors and possibly cancer. Not only did the burgers with the spice mixture—a palatable blend of oregano, rosemary, ginger, black pepper and others—have lower levels of malondialdehyde when tested in the lab, but subjects who ate the spiced burgers had fewer DNA breaks in their cells afterwards.

Of course, the healthfulness of spices and herbs is nothing new to some—traditional medicine all over the world has been using them in remedies for millennia. Although many such uses have yet to be validated by experimental studies, new benefits are being suggested by studies all the time. Take ginger—three University of Georgia pilot studies (not yet published) suggest that eating a small amount of ginger daily for 11 days or more can reduce muscle pain and inflammation after exercise.

The U.C.L.A. and Georgia studies were funded by the McCormick Science Institute, the spice company's research arm dedicated to performing and funding studies on the biophysiological effects of the spices it sells. Obviously McCormick hopes to benefit if people start eating more spices in the interest of health. But the work they fund represents only a small fraction of the dozens of studies appearing independently from research institutions around the world—Italian researchers found that saffron improves vision in the elderly; Thai scientists showed that ginger aids digestion—adding to a growing body of work suggesting that spicing things up a little adds more than just flavor.