Hi folks. I take ascorbic acid (main component of vitamin C complex) daily, and in high doses with acute symptoms (I also take multiminerals so perhaps I'm ok with regards to copper levels etc). By high doses I mean anything up to 16 grams a day, with a minimum of about 3g daily. It seems to reduce the severity and duration of my acute symptoms, which are commonly severe migraine-like headaches, neck, muscle and joint pain. My reading suggests that ascorbic acid is eliminated by the body very quickly and that a general rule of thumb is that the more unwell you are the more vitamin C you can take before reaching bowel intolerance level. I don't know if that is factually accurate but it seems to be the case for me.
Interestingly, I read that Japanese scientists post-Hiroshima and Nagasaki found that vitamin C helps protect us from radiation. And I know some studies were treating cancer and AIDS patients with doses up to 160 grams per day with positive results.