Thanks for checking in. Same as you mine was limited to the butterfly and not too much else (also ears and scalp).
With foods I found a strategy that kind of worked better than avoiding. At-least I think it did. Basically instead of avoiding I just started to focus on what I should be eating, instead. The simple change from what to avoid, to what to eat was quite helpful in reducing and associated stress from food limitations.
The emotions and stress aspect seem to play into the hormonal aspect of seborrheic dermatitis. And yeah it definitely get's difficult to pin anything down with so many variables at play.
After learing a bit about skin cell microbiology I think a piece of this, which is not often mentioned, is how some of these cells and bacteria work. About 90% of the individual microbial cells found on the skin are actually dormant (metabolically inactive). So some of these treatments that target the reproduction mechanism of the bacteria are really only effective on the active ~10%. Now how much of these 10% might be bad and how much are the good ones that are protecting our skin? So perhaps some of these treatment approaches can seem effective as that 10% is killed off, but what happens? As the inactive cells activate perhaps the ratio of good to bad cells becomes disrupted even further and the SD actually progresses.. This avenue of research is quite interesting and has only been gaining momentum in recent years (due to technological advances).
Yeah, for the ACV and the sea salt I think pin pointing the exact concentration can be of benefit. For the sea salt I would image trying to mimic natural salt water salinity would be the best. In a majority of medical studies a concentration of 5% is used (source). As for ACV, it's hard to imagine what the perfect ratio would be and I wish more research was done in this area.
As for the Restoraderm, I contacted them earlier this week about samples. They said I should tell Canadian readers to contact them at firstname.lastname@example.org and they can send out samples. Hopefully, your in Canada and can benefit from this.
Yeah, I attempted making my own vitamin c serum on a few occasions as I read that it's better made fresh. It didn't really do much for me, except sting the affected areas. Vitamin C seems quite good internally though and I noticed it had an effect of reducing the heat sensation. If I was to go down this route again, I would probably try something like this or this. I've got a gut feeling that arginine has a large role in the effectiveness of the Restoraderm. However, I haven't tried these products myself.
Hope that covers all your questions. Perhaps join the community to discuss things further. Best of luck.