This is a wonderfully healing and mineral rich smoothie. Don't be afraid of the comfrey! It is very safe to eat and use every day (yes, internally!). It is one of the best healing herbs that there is, but it has gotten a bad rap. If you are still hesitant, then just leave it out.
Here's a very informative and interesting article on the use of comfrey: http://www.herballegacy.com/ThesisContraIndications.html
i swear by this stuff! this non-alchy elixir gave me more energy throughout the day, than a cup of coffee (and i took one shot!) perfect for a mid-day pick-me-up, a quick burst of energy for a busy night, or whenever you just want to feel good and clean from the inside out!