Maybe the connection lies in that both NAC and Mastic Gum have been known to work on harmful bacteria in the gut, H Pylori for sure, but others as well.
Could be that if shown to work in some way, then start targeting bad bugs in the gut at higher doses, not necessarily of these supplements, but others that can be taken at higher doses safely
The gut bugs are morphing and becoming resistant to everything. So could be you make a dent, then they get strong fast, and the same dose does not work.
I had a similar experience with NAC.
Edit: This is going by my own theory connecting AF to the gut, based on my own experience.