Combine the first 6 ingredients in a blender; process until smooth. Sprinkle with flaxseed, if desired.
Flaxseed boosts heart health and may enhance vision. You can find it in health-food stores already ground. Or grind whole flaxseed in a spice grinder or with a mortar and pestle. Store it in the refrigerator or freezer to keep it fresh. Enjoying this smoothie also helps you meet your daily calcium needs.