I am very familiar with juicing and other methods of detoxing the body, and I believe that juicing and fasting is a very powerful tool to help rebuild and repair damage to the body. Although, you may feel like your dying after a certain period of time during a fast,(and in some cases you actually can)> This is why your fast should be medically supervised if you expect to do an extensive cleanse.
The last point I want to make is that a Traditional AMA Doctor probably will not agree to the validity of juicing and fasting or agree to take legal responsibility for supervising your fast. It has to be an MD who is also thoroughly versed in Natural and Alternative Medicine.
In the final analysis juice fasting and other forms of detoxing can provide tremendous health benefits for the body, mind and soul.