Place flaxseed in a clean coffee grinder or blender; process until coarsely ground. Lightly spoon flour into dry measuring cups; level with a knife. Combine flaxseed, flour, baking powder, baking soda, and salt in a large bowl; make a well in center of mixture. Beat cream cheese and the next 5 ingredients (cream cheese through egg white); stir in sweet potato. Add to the flour mixture, stirring just until moist.
Spoon batter into an 8 x 4-inch loaf pan coated with cooking spray. Bake at 350° for 50 minutes or until a wooden pick inserted in center comes out clean. Cool 10 minutes in pan on a wire rack; remove from pan. Cool completely on wire rack.
Note: To freeze bread for up to 1 month, place in an airtight container, or wrap in heavy-duty plastic wrap or foil. Thaw at room temperature.