Correlation is not Causation.
True, but it is unclear which or how many other supplements the researchers controlled for. Of the vitamin C users, 3.4 percent developed kidney stones for the first time during the study, compared to 1.8 percent of non-supplement users.
Obviously the vast majority of men taking it are not coming down with kidney stones. That doesn’t mean the findings are useless. I take 500 mg a day with an iron tablet and am going to ask about continuing at my next visit to the doctor.