Good question, Tovah. Of course, you can add any greens to the smoothie. The smoothie recipe itself is not the main idea. The key, for me, is to make it a daily anchor meal. The reason I don't include spinach is because I hate it. My mother, with good intenions, forced me as a kid to eat spinach twice a month. The taste is extremely nauseating to me. So, I prefer to get nitrates from beetroot instead.