Methylcobalamin vs cyanocobalamin

At a glance

Methylcobalamin and cyanocobalamin are both vitamin B12 compounds. They differ only in the upper ligand on cobalt: a methyl group or a cyano group. Their molar masses are 1344.4 and 1355.4 g/mol, so equimolar inclusion rates differ by less than 1 %. The practical differences are light sensitivity, processing stability, cost and how each form appears in the EU lists of permitted sources.

Content per gram and label-claim arithmetic

Both materials are the vitamin compound itself, so there is no elemental-content conversion as with mineral salts. The only choice is whether you compare forms by mass or by molar quantity. One microgram of cyanocobalamin is 0.7378 nmol; one microgram of methylcobalamin is 0.7438 nmol.

The table shows two label claims, set as cyanocobalamin, with the equimolar methylcobalamin quantity (ratio 1344.4 ÷ 1355.4 = 0.9919).

In the other direction, 1,000 µg of methylcobalamin is equimolar to 1,008.2 µg of cyanocobalamin. Agree with your regulatory team whether the declared vitamin B12 figure is the mass of the compound added or a molar conversion. The difference between the two approaches is under 1 %.

Because claims are in micrograms, both forms are usually handled as triturations on a carrier such as dicalcium phosphate or mannitol. Powder needed equals the label claim divided by the content stated on the certificate of analysis. As an illustration, if a certificate stated 1.0 %, 1,000 µg would need 100 mg of trituration and 25 µg would need 2.5 mg. Add any overage separately with the overage calculator.

SoleChem sends the specification sheet and certificate of analysis with its quote; state the form and grade you need in the quote form.

Solubility, taste and processing

Both forms dissolve in water, and at microgram inclusion rates solubility rarely limits a formulation. Taste is negligible at these levels. Both are red compounds, so high-potency blends can tint or speck white tablets and powders.

Light is the main processing difference. The cobalt to methyl bond in methylcobalamin is photolabile, and exposure converts it to hydroxocobalamin. Weigh and blend under reduced light, prefer opaque capsule shells and use light-protective packaging. Cyanocobalamin is the most stable of the common cobalamins, which is why many vitamin premixes use it.

Both forms are sensitive to reducing agents, particularly in liquids and moist premixes. Degradation in the presence of ascorbic acid is a well-documented route. Separate the two where the format allows and confirm the choice with stability testing.

Content uniformity needs attention at microgram levels. Use a trituration or geometric dilution, and validate blend uniformity for each batch size.

EU regulatory status

Annex I of Directive 2002/46/EC lists vitamin B12, expressed in µg. Annex II lists the substances that may be used as its source in food supplements, and cyanocobalamin is listed there. Methylcobalamin is also listed, with no condition attached to the entry; the current Annex II text, including this entry, comes from Commission Regulation (EC) No 1170/2009. The permitted forms guide explains how to read Annex II.

Fortified foods follow a separate list in Annex II of Regulation (EC) No 1925/2006. That list includes cyanocobalamin and hydroxocobalamin as vitamin B12 sources but not methylcobalamin, so methylcobalamin cannot be used as a vitamin B12 source in fortified foods.

Maximum amounts of vitamin B12 in food supplements are set nationally and differ by member state. See maximum levels by EU country and the labelling guide for declaration rules.

Descriptors that imply a benefit from choosing one form fall under Regulation (EC) No 1924/2006. Check any such wording against the EU Register of nutrition and health claims and the health-claims guide.

Choosing between them

• Multivitamin tablets and premixes: cyanocobalamin usually costs less per microgram and tolerates compression, heat and storage better.
• Brand specification: choose methylcobalamin when the product brief names it, and budget for light protection in production and packaging.
• Liquids and gummies: both forms need stability testing; cyanocobalamin gives more margin where heat, moisture or reducing agents are present.
• Combinations: products can combine methylcobalamin with cyanocobalamin or other cobalamins. Each form must appear in Annex II, and the label declares total vitamin B12.