Re: why can't I

Bottled lemon juices have been heated to high temperatures to kill the enzymes and preserve the freshness of the juice. However, it is the live active enzymes that are an essential element in the cleansing aspect of the Master Cleanse. The enzymes help digest and loosen the mucoidal mass lining the intestines. (the cayenne pepper does this too, but through a chemical reaction, not enzymatic).
I suppose anyone doing Master Cleanse simply for weight loss could use bottled juice; but since this is intended to be a cleansing protocol live enzymes are absolutely essential for The Master Cleanse to be successful.