Is this helpful for my Knee?

Well if you have had a chance to look at my running log then you might have noticed that I have not been running for the past couple of weeks. Based on what I read, I am giving my knee some more time to heal and this time I am trying to take it slow and not run a marathon in first go . I did go ahead and add some diet supplements to my daily routine. As I was wandeing the aisle of the local Costco store I came across this Joint Juice. There was some kind of promotion going on this product and I tried it. It was like Fanta with some citric taste rather than sweet. I kind of liked it. And on top of that a can is 8 Fl oz and just 30 calories. It says that you got to try the product for ~30 days before you would feel any kind of difference. I am giving it a shot to see if it makes any kind of difference. I might wait out this week more before I start my runs again as my knee feels much better after a 3 week rest. What also interested me is that I saw glocosamine tabs, gels, liquid all over the asile. I dont know much about it but is it something that important. I got to read more about it.
Does anyone know the bad part about glucosamine ( I can read good things about it all over the net).?