TUESDAY, Feb. 5 (HealthDay News) -- Men who take high doses of vitamin C may face double the risk of kidney stones than men who do not, new research says.
Although the finding doesn't directly prove that vitamin C is at fault, and the actual occurrence of kidney stones -- the tiny mass of crystals that can painfully clog the urinary tract -- remained fairly rare, the findings raise questions about whether large doses of the vitamin are dangerous to the body.
"It is important that the public is aware that there may be risks associated with taking high doses of vitamin C," said study co-author Agneta Akesson, an associate professor with the Karolinska Institute in Stockholm, Sweden. "Those with a history of kidney stones should consult their doctor before taking high-dose vitamin C supplements."
Researchers have suspected that large amounts of vitamin C may increase the risk of kidney stones because the body breaks down the vitamin into a substance called oxelate, a component of the stones, Akesson said.
In the new study, which was published online Feb. 4 in the journal JAMA Internal Medicine, researchers tracked more than 23,000 Swedish men who were between 45 and 79 years old in 1997. The researchers followed the men, who hadn't previously been diagnosed with kidney stones, until 2009.
About 900 of the men regularly took 1,000-milligram doses of vitamin C, and 31 of them (3 percent) developed kidney stones. Of the rest of the larger group, fewer than 2 percent developed kidney stones.
After the researchers adjusted their statistics so they wouldn't be skewed by factors such as high or low numbers of men of certain ages, education levels and body weights, the researchers found that those who took the high-dose supplements had an increased kidney stone risk of between 1.7 and 2.2 times.
It's easy to find vitamin C tablets in the 1,000-milligram siz
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