It's possible to take too much of just about anything, right? How does anybody really know until he notches the amount up and up until he finds his own limit? Doesn't excessive V-C generally just pass?
It passes but too much passing through at the same time can cause diarrhea and GI upset.
and in turn depletes the body of nutrients. knee shot.
If anybody lives on a diet of vitamin C, more than depleted "knee shot"s are going to happen.
Obviously, you had better eat well all around so that the V-C has something to work with.