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Is Too Much Vitamin B12 Hard on Your Kidneys?

Updated: May 2

There are several different forms of vitamin B12 that exist. The two most commonly supplemented forms are methylcobalamin and cyanocobalamin. Cyanocobalamin is an inactive synthetic form that generally does not occur in nature. Methylcobalamin is natural and is considered the active form of vitamin B12.

Do Certain Forms of Vitamin B12 Contain Cyanide?

As a matter of fact, cyanocobalamin does contain a small amount of cyanide. However, a 1000 microgram dose of this form of vitamin B12 has about 1/10th the amount of cyanide that is recommended as the maximum water level by health Canada (200 micrograms cyanide per litre). In other words, some people likely get much more cyanide from drinking water - and this level is still considered safe by Health Canada.

Is Cyanocobalamin Safe in Kidney Disease?

However, while data suggests this amount of cyanide is not a problem for most people, some researchers suggest that people with kidney impairment may have difficulty removing it from the body easily and cyanide can build up.

A 2013 study assessed several studies examining the impact of B12 on longevity in patients with kidney disease, and all six studies yielded the same result: there were more surviving patients in the groups that did not supplement B12, and fewer in those who did supplement.[1] Whereas, in people with healthy kidneys, this trend is either not seen at all or found to be the opposite in research.

A 2010 study also found kidney function declined much quicker in one form of kidney disease in those who supplemented B12 compared to no supplementation.[2]

It is difficult to 100% confirm all forms used in these studies were cyanocobalamin, but the ones that did mention the type of B12, did use cyanocobalamin and this is often the most commonly supplemented form.

What Form of Vitamin B12 is Best for Kidneys?

Vitamin B12 is still crucial, and deficiencies can lead to serious complications, warranting prompt treatment. Theoretically however, choosing a natural form such as methylcobalamin, may be more helpful for those with kidney disease who have a confirmed deficiency as it is a natural form of vitamin B12 that does not contain cyanide.

What Dose of Vitamin B12 is Safe in Kidney Disease?

The dose of vitamin B12 should be based on a person’s blood work. The right dose should help an individual reach a healthy blood level of vitamin B12 without going too high.

Why Is Vitamin B12 Important in Kidney Disease?

Vitamin B12 is important in those with kidney disease who have a deficiency because some studies have suggested that it can help prevent some of the common complications seen in kidney disease: cardiovascular problems, cognitive decline and anemia.

Can Vitamin B12 Levels be Tested?

Yes, at our clinic we test vitamin B12 levels to screen for deficiencies and treat accordingly.

Related Topics: Treatments Dialysis Hyperparathyroidism Supplements Bad For Kidney Vitamin B12 Natural Therapies Solitary Kidney


[1] Effect of Folic Acid, Vitamin B6 and Vitamin B12. Supplementation on Mortality and Cardiovascular. Complication among Patients with Chronic Kidney Disease: an Evidence-based Case Report Alvin Nursalim1 , Parlindungan Siregar2 , Indah S. Widyahening3

1  Faculty of Medicine, University of Indonesia, Jakarta, Indonesia. 2  Department of Internal Medicine, Faculty of Medicine, Universitas Indonesia-Cipto Mangunkusumo Hospital, Jakarta, Indonesia. 3  Department of CommunityMedicine, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia. Correspondence mail: Green Mansion, Jl. Green Diamond 3 no. 36, Daan Mogot, Jakarta. email: Link

[2] House AA, Eliasziw M, Cattran DC, Churchill DN, Oliver MJ, Fine A, Dresser GK, Spence JD. Effect of B-vitamin therapy on progression of diabetic nephropathy: a randomized controlled trial. JAMA. 2010 Apr 28;303(16):1603-9. doi: 10.1001/jama.2010.490. PMID: 20424250.



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