Methylcobalamin vs Cyanocobalamin: Which B12 for Vegans?

Vitamin B12 is essential for nerve function, red blood cell production, and DNA synthesis. For vegans, getting enough B12 is a challenge because it's naturally found only in animal products. Two common supplemental forms are methylcobalamin and cyanocobalamin. But which one should you choose? Let's look at the science.

Vitamin B12 (cobalamin) is a water-soluble vitamin that plays a key role in the normal functioning of the brain and nervous system, and in the formation of red blood cells. It's also involved in the metabolism of every cell in the body, especially affecting DNA synthesis and regulation, fatty acid synthesis, and energy production. A deficiency can lead to megaloblastic anaemia and neurological issues like numbness, tingling, and memory problems. Since plants don't produce B12, vegans must rely on fortified foods or supplements.

Most B12 supplements come in two forms: cyanocobalamin and methylcobalamin. There's also adenosylcobalamin and hydroxocobalamin, but these are less common in oral supplements.

Cyanocobalamin

Cyanocobalamin is the most common and cheapest form. It's synthetic, made in a lab, and contains a cyanide molecule. Don't worry — the amount is tiny (about 20 micrograms per 1000 mcg tablet) and is safely removed by the body. The body converts cyanocobalamin into the active forms (methylcobalamin and adenosylcobalamin) through enzymatic processes. It's stable and has a long shelf life.

Methylcobalamin

Methylcobalamin is a naturally occurring form found in animal foods. It's already in the active coenzyme form, meaning it doesn't need conversion. Some people believe this makes it superior, especially for neurological health. However, it's less stable and more expensive.

A 2017 review in the journal Nutrients compared the absorption and effectiveness of different B12 forms. The authors concluded that both cyanocobalamin and methylcobalamin are effective at raising B12 levels in the blood, and there's no strong evidence that one is better than the other for the general population. (PubMed link)

But human studies are limited. (PubMed link)

For vegans, the priority is to get enough B12, regardless of form. The NHS says adults need about 1.5 micrograms of vitamin B12 a day.

Both forms are vegan-friendly, but check the label — some supplements contain gelatin or other animal-derived ingredients.

Cyanocobalamin's cyanide content has raised concerns, but the amount is negligible. For most people, this is not a concern.

Methylcobalamin is often touted as 'better' but it's more expensive and less stable. Some people report that methylcobalamin causes acne or anxiety, but evidence is anecdotal.

For most vegans, cyanocobalamin is a perfectly adequate and cost-effective choice. If you have a medical condition, speak to your doctor. The most important thing is to take a reliable B12 supplement consistently. If you're unsure, consult a healthcare professional.