Hi, Everyone. A doctor years ago recommended for me to take 1,000 mg Vitamin C in the morning and another 1,000 mg pm. I believe it was to help with my chemical sensitivities and because I live next to busy streets and a freeway. (I'm breathing in lots of black dust, even with a fairly good quality air purifier,) I haven't, and I'm not able to get back to see that Doctor. I need to give samples for a test over several days to rule out something medically. I was reading the instructions and it said not to take over 500 mg of Vitamin C a day for a period of time before and during the sample collection. My question is, I'm not sure if I need to titrate down over a period of time the Vitamin C, or what is the safest and best way to do this. I don't have another Doctor I can see at this time that I think is knowledgeable enough with supplements to advice me. Is anyone knowledgeable about Vitamin C and dosing down after years of using 2,000 mg a day that can help me? Thank you for anything you can share.