Well I was reading some website and it was talking about "5 magic veggies" that you could add to fruit smoothies to enhance the nutritional profile and not change the taste, I only remember two: Spinach (this works extremely well) and romaine lettuce. DO NOT USE ROMAIN LETTUCE IN A SMOOTHIE. It will you up in the sense that you are thinking "Oh a strawberry smoothie" then you drink what can only be described as the contents of the cup featured in two girls one cup, after it has aged for two months.