London, Feb 6 (IANS) Daily intake of vitamin C supplements doubles men's risk of suffering from kidney stones, suggests a new research.
"It has long been suspected that high doses of vitamin C may increase the risk of kidney stones," said Laura Thomas, from the Karolinska Institutet in Stockholm, Sweden, who led the study.
This is because some of the vitamin C absorbed by the body is excreted in urine as oxalate, one of the key components of kidney stones. They are made up of tiny crystals, which can be formed by calcium combining with oxalate, the journal JAMA Internal Medicine reports.
"Vitamin C is an important part of a healthy diet," Thomas said. "Any effect of vitamin C on kidney stone risk is likely to depend both on the dose and on the combination of nutrients with which it is ingested."
The study tracked more than 22,000 middle-aged and elderly for 11 years. The current analysis included 907 men who said they took regular vitamin C tablets and more than 22,000 who didn't use any supplements, according to the Daily Mail.
Swedish supplements, like those the study participants would have taken, typically contain about 1,000 milligrams (mg) of vitamin C per tablet. Most vitamin C supplements sold in the UK contain either 500 or 1,000 mg.
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.
The researchers said that because there are no clear benefits tied to taking high-dose vitamin C, people who have had stones in the past might want to think before taking extra supplements.
But the findings do not mean people shouldn't get plenty of vitamin C through fruits and vegetables, since the antioxidant is important for bone and muscle health - and severe deficiency can cause scurvy.