A spice is any pungent, aromatic plant substance—whether tree bark (such as cinnamon), fruit (peppercorns), root (turmeric), or seed (nutmeg)—used whole, broken, or ground up to season and color foods. (In contrast, herbs are plant leaves and stems, fresh or dried; they also add flavor.) The average American consumes more than 3½ pounds of spices annually, three times as much as 50 years ago, thanks largely to the growing popularity of spicy ethnic cuisines. About one-third of that is pepper and mustard seed (in prepared mustard).
Though the amounts we consume at a given meal are tiny, spices and herbs add variety and complexity to our diets. Besides small amounts of vitamins and minerals, they contain a range of other potentially healthful compounds.
Don’t rely on spices and herbs for their curative powers, but do use them to make good foods taste even better and possibly to take the place of salt. They play a particularly big role in healthful plant-based cuisines around the world.