Reading down this post, I had a lot of questions...but this make me reconsider them. Ah, well, TMG is trimethylglycine. A fairly inexpensive supplement that is substrate for the BHMT enzyme. What low-histamine protocol are you using? I bought the low histamine chef cookbook, and it's all too high in histamines for me! Tomatoes??? Are you kidding??? Wasted $15. I have a concise list that works well for me; I will share if you want. If none of the dietary restrictions help, why are you pursuing them? To me, the most severe diet was the low sulfur. If that doesn't help, it's probably not diet-related, in my opinion. At least for my body. BTW, for histamine, you can eat eggs as long as you don't eat the whites raw (like in protein shakes). For your glutathione, I'm not quite remembering it, but there are things that shift production to taurine instead of glutathione or away from it. I'm thinking B6 is a good guy (I need P5P because I'm still deficient with regular B6). I think NAC (N-acetyl cysteine) is a good guy, except if you're histamine intolerant - then it's a very bad guy. Maybe someone can expand on this. I'm a little scattered tonight, myself. Hope some of this is helpful.