Radish, your friend is fortunate to have you. But it sounds to me as if he has an advanced case of orthorexia (inability to see that his extremely restricted diet is bad for him).
However, if he decides he wants to live, I say start him on digestive enzymes, bile salts & HCl, not tom mention good, hearty cooked food. If he is near a practitioner of traditional Chinese medicine, I'd rush him there.
I am hoping for the best and hope you will report back. My own thinking is that when a person is as deficient as he is, it might not be wise to get too hung up on cleansing alone, but sturdy nourishment instead, or in addition to.