INew research from Karolinska Institutet in Sweden
shows that men who take vitamin C supplements
regularly run a higher risk of developing kidney
stones. The study, which is published in the
scientific periodical JAMA Internal Medicine, did
not however observe an increased risk between kidney
stones and multivitamins – which contain lower
concentrations of vitamin C.
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The research is based on data from a large
population-based study of men from Västmanland and
Örebro counties, who were monitored for 11 years. 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 the study period, 436 of the
participants developed kidney stones that required
medical attention. The researchers then compared the
risk of kidney stones in vitamin C-takers with that
in men who did not take any supplements. The
analysis was then repeated for men who took
multivitamins.
The results of the study indicate that men who take
vitamin C supplements (typically 1000 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 regular use of
multivitamins was not found to be associated with
the risk of kidney stones.
The researchers 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 RDI for vitamin C is 75
mg; the vitamin C content of supplements is commonly
1,000 mg per tablet, which is a considerably higher
dose than which is obtained through food.
"As with all research, the results should be
corroborated by other studies for us to be really
sure," says study leader Agneta Åkesson, Associate
Professor at Karolinska Institutet's Institute of
Environmental Medicine. "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."
The study was carried out in association with
urologists and nephrologists at Karolinska
Institutet and Karolinska University Hospital, and
was made possible with a grant from the Swedish
Research Council and with Karolinska Institutet's
KID funding for doctoral education.
For more information
Publication: 'Ascorbic acid supplements and kidney
stone incidence among men: A prospective study',
Laura D K Thomas, Carl-Gustaf Elinder, Hans-Göran
Tiselius, Alicja Wolk, Agneta Åkesson, JAMA Internal
Medicine, online first publication, 4 January 2013.
http://archinte.jamanetwork.com/article.aspx?articleid=1568519
(MDN)
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