I agree that nutrients per calorie is also part of it, which is an unusual metric as was pointed out. The bioavailability metric is just plain cheating (or poor

I agree that nutrients per calorie is also part of it, which is an unusual metric as was pointed out. The bioavailability metric is just plain cheating (or poor math) though since bioavailability is already factored into percent daily value figures. Also, with the sweet potatoes, their vitamin C levels go up by a factor of 8 when cooked, which would rank them much higher on the list. Not many people eat sweet potatoes raw so whether it's good science to assume that they do is reasonably debatable.