In Japan it is often referred to as kumara, while in the United States the most common variety is the Murasaki sweet potato. Regardless of the name, they are essentially identical in nutrition, appearance, and taste.
With its dull purple skin and bright white colored flesh, there's no denying it's a delicious treat. Though when it comes to how much antioxidants there are inside, the answer is disappointing.
Its white creamy texture contains a low amount of phenols, subpar beta-carotene content, and no detectable anthocyanins. If you want the healthiest type, choose a purple sweet potato.
Research Support, Non-U.S. Gov't: Food Chemistry. Volume 103, Issue 3, Pages 829-838 USDA 2007