Stockholm, Sweden (4E) – Swedish researchers have found that men taking high doses of Vitamin C supplements have higher risk of developing kidney stones.
The study by Stockholm’s Karolinska Institue and published in the JAMA Internal Medicine scientific periodical recommends that men who suffered kidney stones before stop taking the vitamin. However, their findings need to be corroborated by other studies, according to study leader Agneta Åkesson, a professor at the Karolinska Institute’s Institute of Environmental Medicine.
The study covered more than 23,000 Swedish men who were observed over a period of 11 years. Of the number, 436 men with an average age of 59 developed new kidney stones. Vitamin C users, especially those taking more than seven tablets per week, were found to have twice the risk of developing kidney stones than non-users.
Each vitamin C supplement tablet in Sweden contains 1,000 milligrams (mgs) of ascorbic acid.
The researchers attributed the formation of kidney stones to the excretion of vitamin C in the form of oxalate, which is also an indicator of calcium oxalate kidney stone formation.
xalate is a salt formed during normal metabolism processes that’s excreted by the kidneys through the urine, according to Livestrong.com. High concentrations of oxalate combine with calcium to form crystals causing kidney stones.
Dr. Robert H. Fletcher of Harvard Medical School, commenting on the study, said the researchers failed to determine the dosages used. Fletcher said the recommended minimal daily intake of vitamin C supplement in the U.S. is 40 to 90 mgs. for adults and 2,000 mgs. per day is not harmful.