Olives are a salty food and many people crave them when the body thinks it needs sodium. Most olives begin life green and then turn black as they age. Olives can be a healthy snack as long as they are consumed in limited quantities. Olives provide fiber, calcium,vitamin E, potassium, magnesium, and antioxidants. They are also good providers of the healthy monounsaturated fats the body needs. A handful of olives a day is a healthy snack.