Scientists have been debating the relationship between vitamin C supplements and kidney stones for decades. In the 1970s the New England Journal of Medicine published heated correspondence about this controversy.
Now Swedish investigators have weighed in with a study of vitamin C supplementation in middle aged and elderly men. Nearly 1000 took large doses of vitamin C regularly. They were matched with about 22,000 men who did not take vitamin C pills. They were followed for more than a decade.
Those who took vitamin C were twice as likely to develop kidney stones than those who did not swallow supplements, but the absolute risk was small. Over the 12 years of the study, roughly 3.4% of vitamin C takers suffered stones whereas 1.8% of the matched controls experienced kidney stones.
In Sweden, the usual dose of vitamin C is around 1,000 mg. This amount could lead to oxalic acid crystals forming in the kidneys. The authors conclude that men should be warned that high-doses of vitamin C may double their risk of kidney stones.
[JAMA Internal Medicine, online, Feb. 4, 2013]

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  1. Yoly

    Correct, what about women? Is ethnicity a variable?
    Yoly from NM
    PEOPLE’S PHARMACY RESPONSE: Kidney stones are more common in men, and the researchers did not study women. Not much ethnic diversity in this Swedish population.

  2. Karen

    The guy in the picture is massaging a muscle, not a kidney. What did he take for the pain?
    Another N=1 study. Would be interested in seeing what other variables were matched, and if the risk was linear with dose.

  3. sonja

    My brother had a terrible kidney stone problem after a heart attack. Operation was impossible so he had to live with heavy bleeding etc. He has never taken any supplements in his life, especially not vitamin C. I know people who take 3-4g a day and have for years and are incredibly healthy. It is rather hard to tell what causes what and what other factors might have been present that could have accounted for the studies 1.6% higher percentage of vitamin C takers.. The thing is we are all different, and what is ok for one person can be wrong for another..

  4. fbl

    Hmmm, I wonder how much water these people drank daily. That should have been a part of the questionnaire.

  5. JKO

    What about women?

  6. Betty F.

    I just cut my prescribed dose in half.

  7. cpmt

    other drugs, some diabetic drugs for example, can cause stones.

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