Of course, as with any other form ot alternative medicine, its effectiveness is unknown, and many physicians believe it may lead to an imbalance of salts, which would tend to diffuse out. It may also weaken the colon through eliminating some of the need for a natural bowel movement. The reported usage by Princess Diana does not necessarily imply that the effectiveness and safety of this procedure is a known fact, and people were moving their bowels safely without a dangerous "toxic buildup" for years before it was even invented!