Vitamin B12: Are You Getting It? (


The typical non-cyanocobalamin forms of vitamin B12 in supplemental forms are methylcobalamin and adenosylcobalamin (also known as 5′-deoxyadenosylcobalamin, dibencozide, coenzyme B12, cobamamide, and cobinamide). Calling adenosylcobalamin “co-enzyme B12” is somewhat misleading because methylcobalam is also a co-enzyme from of B12. Hydroxocobalamin is the form typically used in B12 injections.

Some researchers question whether these non-cyanocobalamin supplements are stable in their oral form. For this reason, much larger amounts are typically used with hope that at least some are absorbed intact. One study suggests that once absorbed, methylcobalamin may be retained in the body better than cyanocobalamin.30

Notes for Introduction
1. Okuda K, Yashima K, Kitazaki T, Takara I. Intestinal absorption and concurrent chemical changes of methylcobalamin. J Lab Clin Med. 1973 Apr;81(4):557-67

Methylcobalamin in a Small Sample of Vegans

Donaldson1 (2000, USA) studied 3 vegans with elevated uMMA levels who were treated with 1/2 to 1 sublingual methylcobalamin tablet (from Enzymatic Therapy, Green Bay, WI), 2 times/day for 3 weeks. Correspondence with the author (March 21, 2002) verified that these tablets contain 1,000 µg methylcobalamin each.

Two of the subjects’ urinay MMA normalized while the remaining subject’s stayed slightly elevated at 4.1 µg/mg creatinine (normal is < 4.0 µg/mg creatinine). Thus, at a rate of 1-2,000 µg/day, methylcobalamin appears to be absorbed at a high enough rate to improve B12 status in some vegans. Additionally, this indicates that the methylcobalamin was able to improve the MMA pathway which requires adenosylcobalamin (in other words, methylcobalamin was apparently converted into adenosylcobalamin in these people).

Notes for Methylcobalamin in a Small Sample of Vegans
1. Donaldson MS. Metabolic vitamin B12 status on a mostly raw vegan diet with follow-up using tablets, nutritional yeast, or probiotic supplements. Ann Nutr Metab. 2000;44(5-6):229-34.

Therapeutic Use of Coenzyme Forms of B12

The coenzyme forms of B12 appear to be more effective in treating certain conditions than is cyanocobalamin (though they are often injected rather than taken orally). Kelly1 (1997) reviewed the research on supplementing with the coenzyme forms of B12 (methylcobalamin and adenosylcobalamin). Results of studies performed on humans are listed here:

Conditions Reported to Improve by Coenzyme Forms of B12
  Therapeutic dose recommended by Kelly1 Conditions reported to improve from treatment1,A
Methylcobalamin 1500-6000 µg/day Diabetic neuropathy
Hyperhomocysteinemia in diabetes
Sleep disordersB
Bell’s Palsy
Adenosylcobalamin, aka:
5′-deoxyadenosylcobalamin, dibencozide, coenzyme B12, cobamamide, and cobinamide
1000-6000 µg/day Neurological problems secondary to anorexia
Hepatitis A
Viral hepatitisB

A – In many cases, treatment was not compared to cyanocobalamin
B – More effective than cyanocobalamin

Notes for Therapeutic Use of Coenzyme Forms of B12
1. Kelly G. The co-enzyme forms of vitamin B12: Toward an understanding of their therapeutic potential. Alt Med Rev. 1997;2(5):459-471.


Hydroxocobalamin is the form of B12 typically found in food. There are not many oral forms for people to take; it is normally injected. One study suggests that after injections, hydroxocobalamin is retained in the body better than cyanocobalamin.1

Notes for Hydroxocobalamin
1. Tudhope GR, Swan HT, Spray GH. Patient variation in pernicious anaemia, as shown in a clinical trial of cyanocobalamin, hydroxocobalamin and cyanocobalamin-zinc tannate. Br J Haematol. 1967 Mar;13(2):216-28.

Vegan Sources of Methylcobalamin

  • Enzymatic Therapy
  • Wonder Laboratories Please note that their statement “The liver does not convert the cyanocobalamin form of vitamin B-12 into adequate amounts of methylcobalamin,” implies that all vegans need a source of methylcobalamin. In fact, most vegans can rely solely on cyanocobalamin. Their Supplement Facts label (to show it is vegan) is below:

    Wonder Labs Methylcobalamin Supplement Facts Label 

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