YOU ARE NOW CONNECTED TO THE TOXLINE (1981 FORWARD, NON-ROYALTY) FILE. ==KIDNEY STONES AND VITAMIN C== 1 AUTHOR Gerster H TITLE No contribution of ascorbic acid to renal calcium oxalate stones. SOURCE Ann Nutr Metab; VOL 41, ISS 5, 1997, P269-82 (REF: 68) ABSTRACT Even though a certain part of oxalate in the urine derives from metabolized ascorbic acid (AA), the intake of high doses of vitamin C does not increase the risk of calcium oxalate kidney stones due to physiological regulatory factor: gastrointestinal absorption as well as renal tubular reabsorption of AA are saturable processes, and the metabolic transformation of AA to oxalate is limited as well. Older assays for urinary oxalate favored in vitro conversion of AA to oxalate during storage and processing of the samples. Recurrent stone formers and patients with renal failure who have a defect in AA or oxalate metabolism should restrict daily vitamin C intakes to approximately 100 mg. But in the large-scale Harvard Prospective Health Professional Follow-Up Study, those groups in the highest quintile of vitamin C intake (> 1,500 mg/day) had a lower risk of kidney stones than the groups in the lowest quintiles. 1 AUTHOR Curhan GC AUTHOR Willett WC AUTHOR Rimm EB AUTHOR Stampfer MJ TITLE A prospective study of the intake of vitamins C and B6, and the risk of kidney stones in men. SOURCE J Urol; VOL 155, ISS 6, 1996, P1847-51 ABSTRACT PURPOSE: The association between the intake of vitamins C and B6, and kidney stone formation was examined. MATERIALS AND METHODS: We conducted a prospective study of the relationship between the intake of vitamins C and B6 and the risk of symptomatic kidney stones in a cohort of 45,251 men 40 to 75 years old with no history of kidney calculi. Vitamin intake from foods and supplements was assessed using a semiquantitative food frequency questionnaire completed in 1986. RESULTS: During 6 years of followup 751 incident cases of kidney stones were documented. Neither vitamin C nor vitamin B6 intake was significantly associated with the risk of stone formation. For vitamin C the age-adjusted relative risk for men consuming 1,500 mg. daily or more compared to less than 250 mg. daily was 0.78 (95% confidence interval 0.54 to 1.11). For vitamin B6 the age-adjusted relative risk for men consuming 40 mg. daily or more compared to less than 3 mg. daily was 0.91 (95% confidence interval 0.64 to 1.31). After adjusting for other potential stone risk factors the relative risks did not change significantly. CONCLUSIONS: These data do not support an association between a high daily intake of vitamin C or vitamin B6 and the risk of stone formation, even when consumed in large doses. 4 AUTHOR Singh PP AUTHOR Kiran R AUTHOR Pendse AK AUTHOR Gosh R AUTHOR Surana SS TITLE Ascorbic acid is an abettor in calcium urolithiasis: an experimental study. SOURCE Scanning Microsc; VOL 7, ISS 3, 1993, P1041-7; discussion 1047-8 ABSTRACT Two sets of animal experiments using guinea pigs were planned to evaluate the effect of ascorbic acid supplementation on the lithogenic process. In the first set of experiments, 10, 40, and 60 mg doses of ascorbic acid/100g body weight/day were given for 105 days. Neither of the ascorbic acid doses given induced crystalluria, calcification or stone formation, thereby confirming our previous findings that ascorbic acid in the doses used by clinicians does not cause urolith formation. In the second set of experiments, ascorbic acid was supplemented in hypercalciuric (induced by calcium carbonate feeding) and hyperoxaluric (induced by sodium oxalate feeding) animals for 45 days. The results indicated that it exacerbated the calcification process in renal and bladder tissue. 9 AUTHOR Singh PP AUTHOR Sharma DC AUTHOR Rathore V AUTHOR Surana SS TITLE An investigation into the role of ascorbic acid in renal calculogenesis in albino rats. SOURCE J Urol; VOL 139, ISS 1, 1988, P156-7 ABSTRACT Neither stone nor calcium oxalate crystal deposition was observed in the kidneys of rats after oral ingestion of 60 mg. L-ascorbic acid daily for three months, although urinary excretion of stone inhibitors (magnesium and citrate) was decreased and oxalate increased. The highly acidic pH of urine and reduced calcium excretion might have prevented their deposition.