ATTRIBUTES: There are many varieties of sweet potatoes — some have yellow flesh, while others are deep orange or even purple. What we call a yam is really a variety of sweet potato. The richer the yellow-orange flesh is in color, the more beta carotene the potato contains. Purple sweet potatoes are an excellent source of antioxidants.
SUPERPOWERS: One yellow-orange sweet potato can contain more than enough beta carotene to satisfy your entire daily requirement of vitamin A. They're also packed with vitamin C and manganese, not to mention 15 percent of your recommended dietary allowance for fiber. And a sweet potato rings in at just about a hundred calories.
WEAKNESS: You'll need to add a little fat to cooked sweet potatoes to aid absorption of the beta carotene.
HOW TO USE THEM: Forget about candied nuts and added sugar. Instead, steam half-inch slices of sweet potatoes for seven minutes to maximize their nutritive properties. Then toss with toasted walnuts and a light vinaigrette for a tasty side dish.