Preheat the oven to 350°F. Coat a 10 inch tube pan with cooking spray. Set aside.
Use an electric mixer to combine the sugar and butter at medium speed until well blended, about 4 minutes. Add the egg whites and eggs, one at a time, beating well after each addition. Beat in the vanilla.
Combine the flour, baking powder and salt in a bowl, and whisk to blend. Add the flour mixture to the sugar mixture alternately with the buttermilk, beginning and ending with the flour mixture.
Pour the batter into the prepared pan; bake about 50 minutes, or until a toothpick inserted into the center comes out clean. Cool in pan 10 minutes; remove from pan and cool, upright, on a wire rack.
Slice the pound cake and serve with fresh fruit and whipped cream, as desired.