I disagree that it is a fallacy that toxins from the bowel are not absorbed into the bloodstream. At the very minimum, a colon loaded with toxic waste from years of neglect from less than fully evacuated waste matter interferes with normal absorbtion of wastes from the bloodstream INTO the colon. In other words, the colon operates at less than maximum efficiency.
A professionally administered colonic is an excellent way to cleanse the bowel BEFORE a fast so you are ready to receive the maximum benefits the fast can provide.
Personally, I look forward to a daily enema during either a juice or water fast, especially during the first few days when I tend to get headaches. An enema is the surest way I've found to quickly relieve a headache, and an enema seems to reduce my urge to eat during those first few days.