Very harmful.  I remember my sister getting some kind of a rash or
sores
all over her body when she was taking too much vit. c.  this was about
10
years ago, so I cant recall exactly what happen to her..........  but
I
do remember it was caused by vit. c. *and no I cant ask her, she's
passed
on since then* not from vit. c.  =o]