As we turn our clocks ahead for Daylight Saving Time, we'll get an extra hour of sunlight and more opportunities to catch some rays to make our own vitamin D. But the sun can't be counted on to supply all the vitamin D we need, especially in the winter or if you wear sunscreen. That's part of the reason experts say many Americans are D-ficient in this vital nutrient. More on Vitamin D Day with Food Network Star Ellie Krieger