What is the difference between hydroxocobalamin (Vitamin B12) and methylcobalamin (Vitamin B12)?

From the Guidelines

Hydroxocobalamin and methylcobalamin are both forms of vitamin B12, but they differ in their chemical structure and some clinical applications, with hydroxocobalamin being the preferred form for treating deficiency due to its longer half-life and better tissue retention, as recommended by the British Obesity and Metabolic Surgery Society guidelines 1. The main difference between hydroxocobalamin and methylcobalamin lies in their chemical structure, with hydroxocobalamin having a hydroxyl group attached to the cobalt atom, while methylcobalamin has a methyl group.

• Hydroxocobalamin is often used as an injectable form of B12 for treating deficiency because it has a longer half-life in the body and is retained better in tissues, making it effective for less frequent dosing, as seen in the treatment guidelines for vitamin B12 deficiency 1.
• Methylcobalamin is the active form of B12 that's directly used in the body for nerve function and DNA synthesis, and it's more readily available for neurological functions and doesn't require conversion like other forms, making it commonly used in oral supplements and potentially beneficial for neurological conditions. Some key points to consider when choosing between hydroxocobalamin and methylcobalamin include:
• The route of administration needed, with hydroxocobalamin being more suitable for injectable forms and methylcobalamin being more suitable for oral supplements.
• The presence of neurological symptoms, with methylcobalamin being potentially more beneficial for these conditions due to its direct availability for nerve function and DNA synthesis.
• The specific clinical situation, with hydroxocobalamin being the preferred form for treating deficiency due to its longer half-life and better tissue retention, as recommended by the British Obesity and Metabolic Surgery Society guidelines 1. It's also worth noting that both forms effectively treat B12 deficiency, but the choice between them depends on the specific clinical situation, route of administration needed, and whether neurological symptoms are present, as highlighted in the guidelines for nutritional recommendations for adult bariatric surgery patients 1 and pregnancy after bariatric surgery 1.

From the FDA Drug Label

Hydroxocobalamin shares the cobalamin molecular structure with cyanocobalamin. The FDA drug label does not answer the question.

From the Research

Difference between Hydroxocobalamin and Methocobalamin

• Hydroxocobalamin and methocobalamin are two different forms of vitamin B12, which is essential for various bodily functions, including the production of red blood cells and the maintenance of the nervous system 2.
• Methocobalamin is one of the two active co-enzyme forms of vitamin B12, primarily involved in hematopoiesis and brain development during childhood, while hydroxocobalamin is another form of vitamin B12 that can be used to treat vitamin B12 deficiency 2.
• Hydroxocobalamin has been shown to be effective in treating vitamin B12 deficiency, and it may be preferable to cyanocobalamin in patients with renal impairment 3, 4.
• Methocobalamin may also be beneficial in patients with renal impairment, as it does not lead to the accumulation of cyanide, which can be harmful in patients with renal failure 3, 4.
• A study comparing the effects of hydroxocobalamin and cyano-B12 supplementation found that both forms of vitamin B12 were effective in improving vitamin B12 status, but hydroxocobalamin may have a slower increase in serum cobalamin levels 5.
• Another study found that all supplemental or food-derived B12 forms, including hydroxocobalamin and methocobalamin, are reduced to a core cobalamin molecule, which converts to the intracellular active forms: methylcobalamin and adenosylcobalamin, in a ratio not influenced by the form of B12 ingested 6.

Bioavailability and Utilization

• The bioavailability of hydroxocobalamin and methocobalamin may be influenced by various factors, such as gastrointestinal pathologies, age, and genetics 6.
• Polymorphisms on B12-related pathways may affect the efficiency of absorption, blood transport, cellular uptake, and intracellular transformations of vitamin B12, and supplementing with a particular form of B12 may be more beneficial for individuals with specific genetic polymorphisms 6.
• However, for the majority of the population, all B12 forms may likely have similar bioavailabilities and physiological effects, and it may make sense to employ the least-expensive form of B12, such as methocobalamin 6.