After adjusting for other potential stone risk factors the relative risks did not change significantly. These data do not support an association between a high daily intake of vitamin C or vitamin B6 and the risk of stone formation, even when consumed in large doses. It would appear that the theory of increased risk of kidney stones from high-dose vitamin C is not substantiated in the real world. I have several comments to add to this. The most important is that vitamin C is inestimably safer than ANY drug.
C does seem to play a role in absorbing iron.
Perhaps there is a link between chronic vitamin C deficiency and anemia. It seems to me that the first thing someone with low iron levels should do is increase their vitamin C supplementation. Chronic vitamin C deficiency leads to a low state of health, no question. To consider that taking supplementation should be avoided because it may make things worse if you stop is ridiculous. Posting that details this issue more.