Vitamins C and B6 and Kidney Stone Risk in Men

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Vitamins C and B6 and Kidney Stone Risk in Men

Most nutritionally oriented doctors know that limited research links vitamin B6 supplementation with protection from calcium oxalate stone recurrences.(1) The mechanism presumably involves the need for B6 in the processing of oxalate. We also know that theoretical concerns about the ability to biosynthesize oxalate from vitamin C have only rarely and tentatively been linked to cases of kidney stones. In fact, most of the "conversion" of vitamin C to oxalate may well occur after urine has left the body.(2,3)

A recent prospective study finds that people taking at least 1.5 g of vitamin C had a 22% decreased risk of forming kidney stones (nonsignificant) -- a comforting finding for practitioners of natural medicine. However, those supplementing at least 40 mg of vitamin B6 only had a 9% decreased risk of kidney stone formation (also nonsignificant).(4) This disappointing decrease in risk in a population of people who had not previously suffered a kidney stone is much smaller than previous reports looking at secondary prevention (preventing stones in those who had previously had at least one kidney stone).

(1) Piesse JW. Nutritional factors in calcium-containing kidney stones with particular emphasis on vitamin C. Intl Clin Nutr Rev 1985; 5(3):110 [review].

(2) Hoffer A. Ascorbic acid and kidney stones. Can Med Assoc J 1985; 132:32

(3) Wandzilak TR, et al. Effect of high dose vitamin C on urinary oxalate levels. J Urol 1994; 151:834-7.

(4) Curhan GC, Willett WC, Rimm EB, Stampfer MJ. A prospective study of the intake of vitamins C and B6, and the risk of kidney stones in men. J Urol 1996; 155:1847-51.

Natural Product Research Consultants, Inc.

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By Steve Austin

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