Sweet potatoes get major points for nutrition (not to mention taste and ease of preparation). They are an excellent source of three major vitamins (Vitamins B6, C, and D) as well as iron, magnesium, and potassium. Their natural sugars release slowly rather than causing blood-sugar spikes. They’re also high in carotenoids like beta carotene, which are important for eye and skin health and associated with lower risk of cancer. (This is where they differ most with yams, which have lower levels of carotenoids.) The dietary fiber provided by one serving is approximately the same as oatmeal. Unless you slather them in marshmallows or too much brown sugar, the more sweet potatoes, the better.