triffid113 I have taken Vit E daily since 2007. It is part of the Cutler Protocol as well. Never really notice much with it but keep taking it because I think that it is important to balance antioxidants. That is interesting about the phenylalanine. I have taken it and tyrosine over the years with varying results. I am off them right now though. I remember that Royal Jelly is supposed to have a form of biopterin as well. I have a hard time breaking down estrogen and apparently I am at risk for male breast cancer. I always wondered whether a higher estrogen played into my getting ME in the first place as this is more often a gal problem ...or the rapid-cycling aspect of Bipolar as this too, is basically a gal thing. The good news is that I have a sauna. And that I can sweat again which makes it doable. Otherwise, it was just a big box that appeared to be designed to kick the crap out of my adrenals I now have a good reason to use it. Another site people there said that BH4 was habit forming....is that true? I have kind of stayed away from it because to the expense, shipping hassles and having to keep it refrigerated. I have thought about it though.