Q: How do the health benefits of raisins compare to those of grapes?

A: Ounce for ounce, raisins have nearly three times the antioxidant capacity of red and green grapes, as measured by one standard test. In fact, they are one of the richest sources of antioxidants of all foods. That’s not surprising, since when fruits are dried, their compounds are greatly concentrated. (It takes more than six ounces of grapes to make one ounce of raisins.)

Most vitamin C in grapes and some heat-sensitive phytochemicals are destroyed in the drying process, but clearly plenty survive, as seen in antioxidant testing. Raisins generally contain little resveratrol, a much-studied antioxidant found in red grapes and wine, either because the raisins are made from green grapes (naturally low in resveratrol) or because the compound is destroyed during drying.

Golden raisins are particularly high in antioxidants because the sulfites used to preserve their color while drying prevent some of these compounds from oxidizing. People allergic to sulfites need to avoid most golden raisins.

Raisins are also a good source of fiber, potassium, iron, and some other minerals. But remember, the drying process also concentrates the sugars and thus the calories, so a half cup of raisins has about 220 calories (versus 50 in a half cup of grapes).