Be *very* careful about the type of vitamin C you use. There are two kinds that I know of: ascorbic acid and calcium ascorbate (the latter is also known as buffered vitamin C). I once tried using high doses of calcium ascorbate to treat chronic health problems (using bowel tolerance as a guide) and gave myself a calcium kidney stone. It turns out that those of us with medullary sponge kidneys should not use buffered C. Even then, I would check with a doctor to be sure and keep the dose low (well below 4 grams) until/unless you are sure. I'll post a follow up to the original question separately.