From my experience the cranberry juice in the grocery stores etc. has too much Sugar in them to really work well. The concentrates in the health food store is the way to go if you are going to use cranberry juice. I wouldn't say cranberry juice is a "kidney cleanse" however it does help your kidneys. If you are looking for a "kidney cleanse" then I recommend the one Andreas Moritz recommends by Present Moments. They will ship it to your house. 1 bag is probably 2-3 20day cleanses.