The addition of pineapple in this smoothie makes it really healthy and nutritious, as pineapple is high in calcium, phosphorus, potassium, vitamin A, and vitamin C, and thus aids in building strong bones and boosts your immune system. To enjoy this healthy smoothie, you just need to take a blender and put 2 to 4 tablespoons of protein powder, 1 cup milk, 1 cup spinach, 1 cup pineapple and 1 tablespoon flax seeds in it. You can add up 1 cup of ice too if desired. Just blend and enjoy!