I would think so, yes. Eating only apples would not be as successful as eating a diet of, say, pineapple or red grapes, but it would certainly do not harm. It may also work to remove stagnant bile and encourage bowel movements to the necessary (natural) one movement per meal.
Are you fond of cacao? I have read a few comments concerning the natural bowel cleansing action of cacao, especially in large amounts, and am considering eating nothing but cacao for a number of days (three, or multiples thereof) to gauge its merit as a natural colon cleanser. This also may be something for you to consider, if you are game...;)