Vitamin C supplements linked to stone risk

February 11, 2013

New research from Sweden shows that men who take vitamin C supplements regularly run a higher risk of developing kidney stones.

New research from Sweden shows that men who take vitamin C supplements regularly run a higher risk of developing kidney stones.

In a research letter, which was published online in JAMA Internal Medicine (Feb. 4, 2013), the authors did not, however, find an increased risk between kidney stones and multivitamins.

As reported in the letter, 48,850 men (ages 45 to 79 years at baseline) were part of a study group who were recruited in 1997 and who provided detailed diet and lifestyle data in a questionnaire. A total of 23,355 men were identified who had no history of kidney stones and who took either no dietary supplements or supplements in the form of vitamin C only.

During 11 years of follow-up, there were 436 incident cases of kidney stones. Ascorbic acid use was associated with a statistically significant twofold increased risk. However, multivitamin use was not associated with kidney stone risk (risk ratio, 0.86), according to the results.

The results indicated that men who take vitamin C supplements (typically 1,000 mg per tablet) are twice as likely to develop kidney stones as men who do not take any dietary supplements. The risk was also found to increase with the frequency of vitamin C supplement use.

The authors believe that both the dose and combination of nutrients with which the vitamin C is ingested are important. For this reason, the observed increase in risk does not apply to a normal dietary intake of vitamin C from fruit and vegetables. In Sweden, the recommended daily intake for vitamin C is 75 mg; the vitamin C content of supplements is commonly 1,000 mg per tablet.

"As with all research, the results should be corroborated by other studies for us to be really sure," said senior author Agneta Åkesson, PhD, of Karolinska Institutet's Institute of Environmental Medicine, Stockholm, Sweden. "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 kidney stones previously."

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