Vitamin C has many functions in the human body. It acts as an antioxidant, it is required for making collagen, L-carnitine, and even neurotransmitters in the brain. Vitamin C also plays a role in the immunity and improves the absorption of iron. Iron absorption is very important because iron is frequently deficient in those with kidney disease. Ongoing research is examining whether vitamin C, by limiting the damaging effects of free radicals through its antioxidant activity, might help prevent or delay the development of certain cancers, cardiovascular disease, and other diseases in which oxidative stress plays a causal role. Oxidative stress is considered harmful because it leads to something called free radicals, which are oxygen-containing molecules with an uneven number of electrons. This uneven number of electrons allows free radicals to react easily with other molecules in the body. Free radicals can cause chemical reactions in the body because they react so easily with other molecules. These reactions are called oxidation and can sometimes be harmful.
As we can see - vitamin C is very important for the body.
Is Vitamin C Good for the Kidneys?
However, kidneys can be quite sensitive to additional substances we introduce into the body, especially if there is already some kidney dysfunction present. For someone with healthy kidneys, vitamin C is likely reasonably safe. However, there are several reports that high doses of vitamin C in those with kidney disease may cause harm. This is because vitamin C is broken down into oxalate in the body. This oxalate eventually has to be removed by the kidneys. If the urine has too much oxalate, it eventually can form oxalate crystals that buildup inside of the kidneys. Research has found that these oxalate crystals cause inflammation, scarring and even renal failure in those with kidney disease.[1]
Reports of Kidney Failure with Vitamin C
A 2015 study reported a case of sudden kidney failure due to oxalate nephropathy in a woman who ingested a high amount of vitamin C.[2] A 2022 study reported kidney failure after high ingestion of vitamin C, and when the kidneys were biopsied they found extensive crystals throughout the tissues of the kidney.[3] A 2023 study again reported a patient with high-dose vitamin C-induced acute oxalate nephropathy (kidney disease).[4]
Is Some Vitamin C Good?
All this being said, research has found that most people with kidney disease are deficient in vitamin C.[5] If someone is deficient, then supplementing vitamin C or changing the diet may make sense. What is most important is the dose. The studies above showed harm with high dose vitamin C. Studies suggest low doses of vitamin C appear to be safe.
Conclusion
Dr. Baker (ND) has a panel of blood testing that checks for dozens of different nutritional, hormonal and metabolic deficiencies that play a role in kidney disease. Reach out if you are interested in learning more.
References
[1] Ermer T, Eckardt KU, Aronson PS, Knauf F. Oxalate, inflammasome, and progression of kidney disease. Curr Opin Nephrol Hypertens. 2016 Jul;25(4):363-71. doi: 10.1097/MNH.0000000000000229. PMID: 27191349; PMCID: PMC4891250.
[2] Sunkara V, Pelkowski TD, Dreyfus D, Satoskar A. Acute Kidney Disease Due to Excessive Vitamin C Ingestion and Remote Roux-en-Y Gastric Bypass Surgery Superimposed on CKD. Am J Kidney Dis. 2015 Oct;66(4):721-4. doi: 10.1053/j.ajkd.2015.06.021. Epub 2015 Aug 10. PMID: 26271145.
[3] Hongsawong N, Chawprang N, Kittisakmontri K, Vittayananan P, Srisuwan K, Chartapisak W. Vitamin C deficiency and impact of vitamin C administration among pediatric patients with advanced chronic kidney disease. Pediatr Nephrol. 2021 Feb;36(2):397-408. doi: 10.1007/s00467-020-04662-9. Epub 2020 Jul 19. PMID: 32683655.
[4] Shen ZY, Chen YR, Wang MC, Chang SS. High-dose vitamin C-induced acute oxalate nephropathy in a renal transplant recipient: A case report and literature review. Asian J Surg. 2023 May;46(5):2223-2224. doi: 10.1016/j.asjsur.2022.11.112. Epub 2022 Dec 5. PMID: 36473810.
[5] Hongsawong N, Chawprang N, Kittisakmontri K, Vittayananan P, Srisuwan K, Chartapisak W. Vitamin C deficiency and impact of vitamin C administration among pediatric patients with advanced chronic kidney disease. Pediatr Nephrol. 2021 Feb;36(2):397-408. doi: 10.1007/s00467-020-04662-9. Epub 2020 Jul 19. PMID: 32683655.