I find the medical abstracts difficult also. Almost as bad as a legal contract. And anytime they try to explain metabolic pathways it's even more difficult. Like you said, even most doctors don't have a good handle on it. It's still a very specialized area of medicine/research that is just now starting to get more attention. I think the genetic testing and the interest in epigentics is shedding more light in this area. Also, so much of this is a result of research on autism and is netting out benefits to other chronic diseases that are on the rise in our modern world. Many kids with autism have metabolic pathway issues as well as digestive problems. Correcting them or managing them can go a long way in reducing or even eliminating the severity of their symptoms.
Regarding the vitamin D. Unless you're getting at least 20 - 30 minutes of sun exposure daily, you're probably low again. Both John and I had low D and we both continue to take it. We took 5000 iu's of vitamin D3 daily for 3 months to get our levels in a normal range and continue to take it to this day but not every day. In the summer, I slack off more because of greater sun exposure. Vitamin D works best when taking Vitamin K2. You can find good formulas that combine the two now. Basically, for every 1000 iu's taken, you can expect to increase your level by 10 point over a three month period. Here's a good site on Vit D that speaks to dosage.
http://www.vitamindcouncil.org/about...my-body-needs/
Make sure you're taking vitamin D3 and not the synthetic D2. Most prescription D is D2 and doesn't work as well.
I'm so glad to hear you're doing better with the copper infusions.
M