Consuming about one-half teaspoon of cinnamon a day for 40 days reduced blood levels of both glucose and triglycerides, a potentially artery-clogging fat, by about 25 percent in adults with type 2 diabetes, a USDA clinical trial found. Cinnamon also cut "bad" LDL cholesterol by nearly 20 percent. And the benefits persisted for up to three weeks after people stopped taking it.

Read more on disease-fighting spices, and take a look at our Natural Medicine Ratings (subscribers only) for more herbal—and spicy—remedies.