Vitamin B12 is essential to our wellbeing.

It protects our DNA, nerve and brain cells and supports our energy and immune systems. It stimulates the production of serotonin – the ‘feel-good hormone’ – which, in turn, can help boost our mood.

It’s found naturally in animal products such as meat, oily fish, eggs and dairy products.  As a result, vegetarians and vegans can sometimes fall short of different types of Vitamin B12 if they don’t balance or supplement their diet very carefully.

What Are the Four Types of Vitamin B12?

While known commonly as ‘Vitamin B12’ it does, in fact, exist in four very similar chemical forms, namely:

  • Methylcobalamin
  • Adenosylcobalamin
  • Cyanocobalamin
  • Hydroxocobalamin

Methylcobalamin and Adenosylcobalamin are both naturally occurring co-enzymes that are found in food sources. They work synergistically in slightly different ways to cover most of your Vitamin B12 needs.

Cyanocobalamin is a synthetic form of Vitamin B12 which the body converts into Adenosylcobalamin and Methylcobalamin before it can be used. The most common and cost-effective form of Vitamin B12, Cyanocobalamin is most often found in supplements and some fortified foods.

Hydroxocobalamin is a highly bioavailable form of Vitamin B12 that is used to treat people with serious deficiencies. It’s only available on prescription and is usually administered by intramuscular shot or in an IV drip.

Multiple B12 Supplements

Let’s look at the four types of Vitamin B12 in more detail here


Methylcobalamin is the most bio-available type of Vitamin B12 which means the body absorbs it more easily. Naturally occurring, it is found in animal-based foods such as meat, fish, milk and eggs so Methylcobalamin B12 is readily available in many people’s daily diets.

It is the most active form of Vitamin B12 and is used mainly in the liver, brain and nervous system.


Adenosylcobalamin is also a naturally occurring, co-enzyme form of Vitamin B12. Consider it a ‘partner in crime’ with Methylcobalamin, as they work in synergy to give pretty much 100% ‘B12 cover’ for your body.

Adenosylcobalamin is particularly important to supporting and protecting the mitochondria in your cells (which the Methylcobalamin can’t do). The mitochondria are like ‘powerhouses’ in each cell and Adenosylcobalamin helps them burn food efficiently to produce energy and boost metabolism.

Additionally, Adenosylcobalamin is a key component of the myelin sheath which protects the nerve cells in the body and brain and enables them to respond very quickly to stimuli.


Hydroxocobalamin is naturally produced by bacteria in the digestive tract when food sources are broken down. It can also be developed in a laboratory by extracting it from microorganisms.

In supplement form, it’s only available on prescription and is usually given by injection under the medical supervision of a GP.  This form of Vitamin B12 is readily converted by the body into Adenosylcobalamin and Methylcobalamin ready for the cells to absorb and use it.


Cyanocobalamin is an artificial form of Vitamin B12 which the body converts into the active forms of Methylcobalamin and Adenosylcobalamin, ready for use. Cyanocobalamin B12 contains a cyanide molecule that gives it stability in products and the body.

Cyanide is a poison, of course, but in the minuscule quantities found in Cyanocobalamin, this is of no consequence – it’s perfectly safe to take!  Being man-made, this form of Vitamin B12 isn’t found naturally in food sources: you’ll only find it in Visupplements. It is the cheapest form of Vitamin B12, but once broken into active forms, it is highly effective.

Salmon Being Sold at Fish Market

Methylcobalamin vs Cyanocobalamin

People often ask which is better – the naturally occurring Methylcobalamin or the synthetic Cyanocobalamin? The jury is out, to be honest: the body does indeed absorb Cyanocobalamin very well but Methylcobalamin is considered to be retained better and for longer out of the different types of vitamins.

What is known is that Methylcobalamin should be combined with Adenosylcobalamin for best results.

How to Treat Vitamin B12 Deficiency?

NHS treats Vitamin B12 deficiency with injections of Vitamin B12.

There are 4 types of Vitamin B12 injections we can offer at IV Boost UK:

  • Hydroxocobalamin
  • Cyanocobalamin
  • Methylcobalamin
  • Adenosylcobalamin

If you think you may have a Vitamin B12 deficiency, it’s best to talk to your GP or clinic to establish how much you are lacking in this vitamin. If it’s only a slight deficiency, a good quality Vitamin B12 supplement combined with a healthier diet will do the trick.

If your deficiency is more serious and you have symptoms of ill-health, a stronger dose of Vitamin B12 may be prescribed to be taken orally, in an IV drip or an intramuscular shot.

Beware! Vitamin B12 is a Prescription Only Medicine that can only be administered by a GMC-registered doctor. Check your clinic is fully licenced to administer this treatment before progressing.

IV Boost is licenced to give Vitamin B12 injections or IV drips and we will only do this following a face-to-face consultation which establishes if this is both necessary and suitable.