Re: It is in fact rectal absorption which largely makes coffee enemas beneficial

Couple of thoughts:

First, the supplement N-Acetyl Cysteine is a glutathione precursor which might help.

However, coffee enemas result in several times as much glutathione production as normal doses of NAC.

Don't know if you saw this article of mine, but perhaps you can find some other suggestions in it:

Building a Foundation for Better Health and Longevity