Posts Tagged ‘kidney stones’

Vitamin C Supplements: Your Express Lane to Kidney Stones

March 18, 2023

Andrew Siegel MD    3/18/2023

Kidney stones are a common problem that urologists confront on an everyday basis.  The first question I routinely ask patients presenting with a stone is: How well do you hydrate?  The second question is: Do you take Vitamin C supplements?  A surprising – almost shocking – number of patients will answer that they take anywhere from 500-2000 mg Vitamin C daily and have done so for years. 

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Megadosing Vitamin C is associated with acute toxicity that can manifest with diarrhea, nausea, vomiting, heartburn, abdominal cramps, and headache. Furthermore, excessive doses of Vitamin C are clearly and unequivocally contributory to promoting the occurrence of the most common type of kidney stone — calcium oxalate — at least doubling its incidence.

Image created by DALL-E, Open AI: Classic colicky pain of a patient with a kidney stone, with a bottle of Vitamin C at hand.

WTF? Why are Americans so supplement-crazed and specifically Vitamin C-crazed?  Who in America these days worries about developing scurvy?** Why do so many people treat Vitamin C like it is M&M candy, taking 1000-2000 mg or more daily?  Vitamin C is conveniently available in so many formulations: pills, gummies, tablets, softgels, caplets, and powder.

** In all fairness, certain populations are prone to scurvy: the elderly, alcohol and tobacco abusers, cancer patients, anorexic patients, those on fad diets, dialysis patients, etc.

Vitamin C

Vitamin C, aka ascorbic acid, is a water-soluble vitamin, an antioxidant, and an essential micronutrient for numerous biological and biochemical functions.  It acts as an electron donor or reducing agent in many chemical reactions and has vital roles in iron absorption, collagen biosynthesis (important for integrity of skin mucus membranes, blood vessels, and bone and wound healing and tissue repair), catecholamine metabolism, etc.  Humans cannot manufacture Vitamin C, so it must be obtained via diet.  Vitamin C is present in citrus fruit (limes, lemons, oranges, grapefruit), berries, kiwi, green leafy vegetables, broccoli, red and green peppers, tomatoes, and potatoes.  The recommended daily allowance (RDA) is 75-90 mg.  Because it is a water-soluble and not a fat-soluble vitamin, it is not stored in the body, so any excess is excreted in the urine. So, virtually all of that supplement ultimately ends up being flushed down the toilet!


Scurvy is a disease resulting from Vitamin C deficiency, the scourge of sailors for many centuries who suffered with it because of long voyages devoid of access to fresh fruit or vegetables.  Symptoms include soft and swollen gums that bleed easily and can separate from the teeth as well as swelling, bruising, poor healing, and ulcerations of various parts of the body. Progressive hemorrhage, lethargy, fatigue, malaise, and emaciation may ensue.  A Scottish scientist by the name of James Lind discovered that the only effective treatment for scurvy was oranges and lemons.  The Royal Navy thereafter successfully treated its sailors with limes to ward off the disease. The nickname “Limeys” for Royal Navy sailors originated among skeptical American sailors who did not believe or were uninformed concerning the magical property of citrus fruit to ward off scurvy.

Linus Pauling

Linus Pauling, a renowned scientist who won two solo Nobel prizes, was an influential figure in popularizing Vitamin C.  His 1970 book: Vitamin C and the Common Cold encouraged Americans to consume huge doses of Vitamin C daily to ward off the common cold.  He also believed that Vitamin C was a panacea for a variety of other ailments and the key to disease-free living and even increased longevity.  Even though he died almost thirty years ago, his legacy survives as the individual most responsible for creating and perpetuated the “Vitamin C myth.”  Multiple studies have demonstrated that Vitamin C has at most a marginal effect on reducing the duration of the common cold.  

Vitamin C-driven kidney stones

The most common type of kidney stone is composed of two components, calcium and oxalate. Vitamin C is metabolized into oxalate and excreted in the urine, resulting in high urinary levels of oxalate. In fact, 30-50% of urinary oxalate derives from ascorbic acid metabolism. Furthermore, Vitamin C in excess can potentially acidify the urine, further increasing urinary oxalate and urinary uric acid levels (another type of kidney stones). Increased oxalate secretion resulting in increased urinary oxalate clearly increases one’s risk for calcium oxalate kidney stones. 

A scientific study provided patients with 1000 or 2000 mg of Vitamin C supplement daily and then measured oxalate levels in the urine. The study demonstrated that with Vitamin C supplementation there is a dose-proportional increase in urinary oxalate levels, elevating the risk for calcium oxalate crystallization and stone formation.  Those enrolled in the study who had a prior history of calcium stones were found to have significantly higher levels of urinary oxalate than none stone-forming subjects both prior to and following the vitamin C supplementation. The study concluded that patients with a history of kidney stones should be discouraged from using vitamin C supplements.

Bottom Line: It is rare for an American to be Vitamin C deficient because Vitamin C is plentiful in a variety of fruits and vegetables, and it is very easy to meet minimum daily requirements.  Vitamin C supplementation is a common practice, perpetuated by a false belief that it has magical powers.  Truth be told, very few Americans need Vitamin C supplementation and there is a very ugly downside to overdoing it, as there is a clear association between Vitamin C and kidney stones, particularly in those with a prior history of kidney stones.  My advice is to get your Vitamin C naturally through healthy consumption of fruits and veggies and avoid unnecessary supplements that end up being flushed down the toilet and may put you on the fast track to a kidney stone.

Wishing you the best of health,

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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery.  He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro AreaInside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, one of the largest urology practices in the United States.  He is the co-founder of PelvicRx and Private Gym.  His latest book is Prostate Cancer 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families. 

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Video trailer for Prostate Cancer 20/20

Preview of Prostate Cancer 20/20

Andrew Siegel MD Amazon author page

PROSTATE CANCER 20/20 is now available at Audible, iTunes and Amazon as an audiobook read by the author (just over 6 hours). 

Dr. Siegel’s other books:

THE KEGEL FIX: Recharging Female Pelvic, Sexual, and Urinary Health


MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health

PROMISCUOUS EATING— Understanding and Ending Our Self-Destructive Relationship with Food