High-dose ascorbic acid supplements — one of the
most commonly used vitamin preparations — are
associated with a dose-dependent 2-fold increased
risk of kidney stone formation among men.
For this study 48 850 men, aged 45 to 79 years at
baseline, were recruited in 1997 (response rate,
49%). Detailed diet and lifestyle data were
collected at baseline using a self-administered
questionnaire.
During 11 years of follow-up researchers ascertained
436 first incident cases of kidney stones.
Analysis of kidney stone material collected from
3176 men, treated with extracorporeal shockwave
lithotripsy in Stockholm County, found calcium
oxalate to be the dominant component in 92.6% (H.-G.T.,
unpublished data). It could thus be assumed that at
least 90% of the kidney stones in this study
population were composed primarily of calcium
oxalate.
Vitamin C is excreted in urine both in its
unmetabolized form and as oxalate.
The results may not be generalizable to women, who
typically have a much lower kidney stone risk.
Because the risk associated with ascorbic acid may
depend both on the dose and on the combination of
nutrients with which the ascorbic acid is ingested,
these findings should not be translated to dietary
vitamin C.
Data on the brand of supplement used were not
available, and the researchers were not, therefore,
able to fully characterize the dose taken.
However, previous studies have demonstrated that
ascorbic acid preparations available on the Swedish
market typically contain 1000 mg of ascorbic acid
per tablet.
Currently there are no well-documented benefits of
high-dose ascorbic acid supplement use, and
therefore, it seems prudent to advise that high-dose
preparations be avoided, particularly by those with
a history of kidney stones.
For more information
Ascorbic Acid Supplements and Kidney Stone Incidence
Among Men: A Prospective Study
Laura D. K. Thomas, MSc; Carl-Gustaf Elinder, MD;
Hans-Göran Tiselius, MD; Alicja Wolk, DrMedSc;
Agneta Åkesson, PhD
AMA Intern Med. 2013;173(5):386-388.
doi:10.1001/jamainternmed.2013.2296
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