Raisins are dried grapes. There are two main varieties - dark and golden raisins, also called sultanas. Raisins are produced by drying grapes in the sun for around 10 days. Clinical studies show that eating raisins can lower blood pressure and cholesterol, and may benefit heart health and smokers. Raisins contain antioxidants, fiber, potassium, selenium, and vitamins A, B, and iron. They have been consumed since ancient Greece and were an important export product from Greece in the 19th century, particularly Corinthian raisins.