The cartridges just have plain old coffee beans or tea leaves/grinded herbs/etc in them. Open one after you use it and you'll see it's exactly the same... The keurig just heats up faster. I make my own tea blends using a reusable k-cup filter. I use L-Theanine, Kava, and Valerian Root for sleep. I make green tea too. I would give you a some links about it, but this is my first post.