About 6 weeks after my son started taking methylfolate (which helped his symptoms considerably) he started having a symptom that we now know is caused by lower zinc - a loss of motivation. Every time he loses motivation I give him some extra zinc and the next day he is back to normal - it appears something happens to the regulation of dopamine during the sleeping hours and you have to have enough zinc. I have a feeling that the increased methylation was and is draining his zinc stores out of his body. 15 mg of zinc isn't enough now, but it was before. Another symptom that he gets is every time this happens he also gets signs of a leaky gut but with sufficient zinc the leaky gut goes away after a few days. I know that methionine synthase, which is produced by MTR, uses zinc and I am trying to find out if there is any other way that having the methylation cycle running at top speed drains zinc. Has anyone else had problems with zinc issues relating to methylation?