Can Vitamin-C Supplements Lead to Kidney Stones?
Vitamin-C and Kidney Stones
Vitamin C (ascorbic acid) is a widely used over-the-counter supplement, valued for its role in immune function and antioxidant activity. The recommended dietary allowance (RDA) for vitamin C in adults is 75 mg per day for women and 90 mg per day for men (Institute of Medicine [IOM], 2000). These requirements are typically met through a balanced diet.
Many fruits and vegetables—including oranges, lemons, green peppers, and broccoli—are rich sources of vitamin C and generally provide sufficient intake without the need for supplementation (IOM, 2000).
Despite this, vitamin C supplements are frequently consumed at much higher doses, commonly ranging from 500 to 2,000 mg per day, particularly following increased public interest in immune support during and after the COVID-19 pandemic (Bailey et al., 2013).
In the body, vitamin C is partially metabolized into oxalate, which is excreted in the urine by the kidneys. Controlled metabolic studies have demonstrated that vitamin C supplementation significantly increases urinary oxalate excretion in both healthy individuals and patients with a history of kidney stones (Massey et al., 2005; Thomas et al., 2000; Wandzilak et al., 1994).
Elevated urinary oxalate can bind with calcium to form calcium oxalate crystals, the most common composition of kidney stones. When oxalate concentrations are sufficiently high, these crystals may precipitate from urine and promote stone formation (Worcester & Coe, 2010). Large prospective cohort studies have shown an increased risk of kidney stone development among individuals who regularly consume vitamin C supplements, particularly at higher doses (Curhan et al., 1999; Ferraro et al., 2016).
Importantly, this risk appears to differ between supplemental and dietary sources of vitamin C. Natural food sources—especially citrus fruits—also contain citrate, a well-recognized inhibitor of kidney stone formation. Citrate reduces calcium oxalate crystallization by binding urinary calcium and increasing urinary pH (Kirejczyk et al., 2014; Worcester & Coe, 2010).
For both healthy individuals and patients with a history of kidney stone disease, obtaining vitamin C primarily from whole foods rather than high-dose supplements can provide adequate daily intake while minimizing the potential risk of urinary stone formation or recurrence.
With this principle in mind, Prevastone Inc. has formulated CERO Multi®, a vitamin C-free multivitamin designed by physicians. CERO Multi® provides essential nutrients in appropriate amounts to complement healthy dietary choices while excluding certain components—such as vitamin C—that may pose risks when consumed in excess.
Key Takeaways:
Many people take 500-2000 mg vitamin-C in supplement form daily, the recommended daily allowance is 75-90 mg
Relying on natural sources of can easily provide you with your recommended daily allowance of vitamin-C
References
Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academies Press; 2000.
Bailey RL, et al. Why US adults use dietary supplements. JAMA Internal Medicine. 2013;173(5):355–361.
Thomas LD, et al. Ascorbic acid supplements and urinary oxalate excretion. American Journal of Clinical Nutrition. 2000;72(2):404–409.
Massey LK, et al. Effect of dietary ascorbic acid on urinary oxalate. Journal of Nutrition. 2005;135(7):1673–1677.
Wandzilak TR, et al. Effect of high-dose vitamin C on urinary oxalate levels. Journal of Urology. 1994;151(4):834–837.
Worcester EM, Coe FL. Calcium kidney stones. New England Journal of Medicine. 2010;363(10):954–963.
Curhan GC, et al. Intake of vitamins B6 and C and the risk of kidney stones in women. JAMA. 1999;281(19):1837–1843.
Ferraro PM, et al. Vitamin C intake and the risk of kidney stones. American Journal of Kidney Diseases. 2016;67(3):400–407.
Kirejczyk JK, et al. Citrate and prevention of calcium stones. Urological Research. 2014;42(6):473–478.
