Methyl vs. Cyano B12
Special note: A study was just released suggesting that the algae chlorella has vitamin B12 activity. I will be reporting on that as soon as I get the paper.
A paper was published in the July edition of Molecular Nutrition and Food Research reviewing the four different forms of vitamin B12 (1). The four forms are cyanocobalamin (CNCbl), hydroxocobalamin (HOCbl), methylcobalamin (MeCbl), and adenosylcobalamin (AdoCbl).
A quick summary is that MeCbl and AdoCbl are the two forms of vitamin B12 that are co-enzymes–the body actually uses these forms and needs both of them. But CNCbl is the form most commonly found in supplements and fortified foods while HOCbl is the form usually contained in B12 shots.
There has been a debate for about the last 10 years as to whether supplementing with the co-enzyme forms is better than supplementing with CNCbl or HOCbl. The paper by Obeid et al. suggests that people do not benefit more from the co-enzyme forms. Even for people with genetic defects of vitamin B12 metabolism, injections with HOCbl are preferable to supplementing with the co-enzyme forms.
Currently, we do not have sufficient evidence to suggest that the benefits of using MeCbl or AdoCbl override that of using CNCbl or HOCbl in terms of bioavailability, biochemical effects, or clinical efficacy. There is uncertainty regarding the claimed superior role of Cbl coenzyme forms for prevention and treatment of Cbl deficiency. However, HOCbl may be an advantageous precursor of the cofactors, particularly in the inherited disorders of metabolic Cbl processing. CNCbl is a more stable and inexpensive form that appears to be best suited for oral supplementation and parenteral [intravenous] treatment as well.
1. Obeid R, Fedosov SN, Nexo E. Cobalamin coenzyme forms are not likely to be superior to cyano- and hydroxyl-cobalamin in prevention or treatment of cobalamin deficiency. Mol Nutr Food Res. 2015 Jul;59(7):1364-72. | link