I wonder if the magic bullet (!) in apples is the pectin? Pectin absorbs water and becomes really slippery, if you've ever had a chance to play with pure pectin powder. Seems like something that could only be helpful to the innards. Good ole black coffee has never failed me in my time of need.
One friend with totally intractable (pun intended?) constipation absolutely swears by EXACTLY seven fat-free Pringles, y'know, with the Olestra. Picture the Monty Python bit - "The count shall be exactly SEVEN. It shall not be six, nor shall it be eight. If the count is six, count one more..." Her tale of how she arrived at seven is beyond hilarious, and should be written up for comedy competition.