High-Dose Vitamin C Linked with Kidney Stones.

High-dose vitamin C supplements (typically 1000 mg per tablet) are linked with a dose-dependent twofold increased risk of kidney stone formation among men, according to an 11-year study of more than 23,000 men. The observed increase in risk did not apply to a normal dietary intake of vitamin C from fruit and vegetables. Because there are no well-documented benefits of high-dose vitamin C supplements, it's wise for individuals with a history of kidney stones to avoid them, the researchers said. The findings are published inJAMA Internal Medicine.