Raisins are dried grapes that have lost most of their water content through sun-drying or dehydrating. They are naturally sweet and high in sugar and calories, but they also contain fiber, antioxidants, and important minerals like iron. Raisins are made from a range of grape varieties, and the most common type of raisin is made from Black Corinth grapes, which are seedless and quite small. They were originally grown in the Mediterranean region and have been used to make raisins for a long time. Today, Greece is the largest producer of currants, and California, Australia, and South Africa also produce currants. Raisins are also a good source of potassium, and studies have found that low potassium levels contribute to high blood pressure, heart disease, and stroke.