Men should be advised that vitamin C supplements in large doses can potentially double their risk of developing kidney stones, according to new research.
Scientists made the discovery after tracking the health of 23,355 men for 11 years.
Compared with men who took no supplements, those regularly taking large-dose vitamin C pills were twice as likely to be treated for kidney stones.
Typical supplement doses were 1,000 milligrams of vitamin C per tablet.
Regular use of multivitamin supplements, containing lower amounts of vitamin C, led to no increase in risk.
No raised risk of kidney stones has been associated with a normal dietary intake of the vitamin from fruits and vegetables.
The risk from supplements also increased with greater frequency of use, the study found.
Lead scientist Dr Agneta Akesson, from the Karolinska Institute in Sweden, said: “As with all research, the results should be corroborated by other studies for us to be really sure. Nor can we say anything about whether women run the same risk as men.
“But given that there are no well-documented benefits of taking high doses of vitamin C in the form of dietary supplements, the wisest thing might be not to take them at all, especially if you have suffered from kidney stones previously.”
The research is published in the journal JAMA Internal Medicine.
In absolute terms, the likelihood of developing kidney stones was still small for men taking vitamin C supplements. Of the total number of men taking part in the study, only 436 required medical attention for the condition.
The recommended daily intake (RDI) for vitamin C in Sweden is 75 milligrams. A one gram supplement contains a much higher dose of the vitamin than is obtained from food.