High ascorbic acid linked to kidney stones

Researchers in Sweden suggest high-dose ascorbic acid may be associated with the risk of kidney stones. Laura D.K. Thomas and colleagues at the Karolinska Institutet in Stockholm, Sweden, evaluated whether ascorbic acid supplements -- a form of vitamin C of approximately 1,000 milligrams -- were associated with the formation of kidney stones in a group of men in Sweden. The study involved 48,850 men ages 45-79 years at baseline. The study participants were part of a study group who were recruited in 1997 and who provided detailed diet and lifestyle data in a questionnaire. During 11 years of follow-up, there were 436 incident cases of kidney stones. The study, published in the journal Internal Medicine, found ascorbic acid use was associated with a statistically significant two-fold increased risk of kidney stones. However, multivitamin use was not associated with kidney stone risk, the study said.