check the ingredients- if there is no added sugar you may be able to have small amounts, but most juices add sugar. even if it doesn't, since juice is so concentrated you generally get more sugar than if you ate the raw fruit- plus you miss out on the fiber and enzymes.
I'm to scared to try it right now LOL I just am starting P3 today & I didn't even try cottage cheese during P2 until yesterday LOL but Jamba will be maybe another week & I might venture in there & read their ingredients to see what would be the best pick :O) I live off Jamba in the summer because where I live it gets HOT!!