Potatoes have a bad reputation in some circles, but they actually add quite a bit of nutrition to a meal. One medium red spud contains 154 calories, 3 grams of fiber, 36 percent of your daily vitamin C needs, 27 percent of your daily potassium needs (more than bananas!), and a slew of B vitamins. Many of these nutrients, including fiber and some iron, come from the potato skin, so feel free to keep them on.