Does a smoothie need both milk and yogurt?

According to High Planes Journal:

"The USDA MyPyramid recommends 2 cups of milk daily for people consuming 1,000 to 1,400 calories and 3 cups of milk daily for people consuming 1,600 calories a day or more. One serving is equal to 1 cup of milk, 1 cup of yogurt, 1 1/2 ounces of natural cheese or 2 ounces of processed cheese."