Vitamin B12: What is it and what does it do?

When we’re young, we’re told that eating our fruits and veggies is good for us because of vitamin C. Even adverts for juice and squash pride themselves on the vitamin C content of their products. Everyone’s heard of calcium and how it’s beneficial for healthy teeth and bones. Everyone knows we need iron for our blood, and vitamin D from the sun to keep us happy. So how come no one is really talking about Vitamin B12, the unsung hero of our nerves and DNA? 

Unless you’re vegan, of course, in which case, everyone’s suddenly an expert. 

One of the first things that happens when you make a switch to a plant-based diet or vegan lifestyle is that everyone becomes concerned about your levels of vitamin B12, despite the fact they may have never worried about their own. True, vitamin B12 is harder to come by in a plant-based diet, but that shouldn’t put you off. Everyone should be keeping an eye on their B12, as it plays several vital roles in your body.

In this guide, we will explore what vitamin B12 is, what it does, and what happens when you don’t get enough of it:


What is Vitamin B12?

B12 is the most chemically complex of all vitamins, and is essential in making red blood cells, nerves and DNA. It is water soluble, which means it can dissolve in water and travel through the bloodstream. However, as it is not created by the body, it needs to be a consistent part of our diet to make sure we’re getting enough.

It is also known as cobalamin. Fun fact: The word cobalamin is a combination of the words ‘cobalt’ and ‘vitamin’ as B12 contains cobalt, an essential trace element, right in the middle of its structure. That’s not vital information, but it will make you sound knowledgeable at parties!

What does B12 do for the body? 

B12 plays a number of crucial functions in the body: 

  • Supporting metabolism: The metabolism of every cell depends on B12. Take your red blood cells for example. They are vital in transporting oxygen and iron around the body, and we produce millions of them every minute. B12 helps these cells to multiply correctly, and without a sufficient amount, their levels drop, which can cause anaemia. 
  • DNA production: It is also vital in the production of our DNA, and ensures the proper functioning of our nervous system. It does this by maintaining the myelin sheath, a substance which covers the nerves of our central and peripheral nervous systems. 
  • Fuelling the body: B12 helps the body to absorb folic acid, which is needed within the body for energy production and release, supporting healthy energy levels and reducing fatigue. This is extra important for those of us living a very active lifestyle, as I’m sure you can imagine!
  • Boosting immune system: It supports your immune system by playing a role in white blood cell production and contributes to healthy brain function. Age related memory decline has been linked with lower levels of vitamin B12 in the brain. 
  • Fighting disease: B12 also plays a role in regulating the body’s levels of an amino acid called homocysteine. This particular amino acid is associated with Alzheimer’s, Parkinson’s disease and cardiovascular disease, so keeping it well regulated is very important. 
  • Keeping you happy: Finally, because we all love a mood booster – regular B12 supplements have been shown to increase your mood, and reduce the symptoms of anxiety and depression. 


How is B12 created or ingested? 

B12, like a number of other micronutrients, is not made by the human body, and therefore must be ingested. 

There is B12 in certain foods, in multivitamins, and in specific supplements, whether in tablet or liquid form. Liquid forms tend to have a higher efficacy due to the fact that they can enter the bloodstream more quickly – no digestion necessary! This also helps those who have difficulty absorbing B12 to get the most out of their supplement. 

B12 is stored by the body by up to 2000 times the amount your body needs day to day, which means that it may take years of not getting enough for a deficiency to become apparent – that doesn’t mean you shouldn’t look at your diet and make sure you’re keeping those stores filled up though!

What foods provide B12? 

Here’s the thing, and it’s a bit of a kicker, really.  

B12 used to be abundant in our soil, and therefore in our food, which is quite probably why humans evolved to rely on it in their diet. However, mass farming and land management practices have all contributed to a lack of naturally occurring B12. Low B12 in the soil means a lack in our food, so we’re not getting what we need from the ground.  

This is the case for all land creatures, so you’ll often find that animals are supplemented with B12 to ensure that it’s a part of the ‘food’ chain. For those of us who eat a whole food plant based diet, it is important to supplement B12 in order to avoid a deficiency. 

There are foods available which are fortified with B12, such as nutritional yeast, plant milks and Marmite, the spread we either love or hate. (I love it so much I don’t think I could ever develop a B12 deficiency, but that’s not the point.) 

Is B12 the same for vegans and non-vegans? 

Yes, the vitamin is the same. Non-vegans will find it easier to get the recommended levels of B12 as animals are supplemented with B12. In my very humble opinion, it’s probably nicer to cut out the middle cow, and take a plant-based, vegan B12 supplement instead. 

Can you have a B12 deficiency? 

Yes. B12 deficiencies are especially common amongst those who eat a plant based diet without supplements or fortified foods. 

It’s not just following a plant based diet that can put you at risk of developing a B12 deficiency. They become more common as we grow older, and are especially common in those who have autoimmune conditions such as Crohn’s Disease, which limits the body’s ability to absorb and digest certain foods. This is also true of anyone who may have had surgery which removes the part of the bowel responsible for the absorption of B12; the ileum.

As B12 is needed to support vital body functions, it’s important to recognise the symptoms of a B12 deficiency, so that you can adjust your intake if you need to. 

Common symptoms of B12 deficiency include fatigue, weariness, weakness and impaired cognitive function. Memory loss is also common. If you are experiencing tingling or numbness in your extremities, then this might also be a sign of B12 deficiency, which can lead to nerve damage. The more serious symptoms include anaemia, a swollen or inflamed tongue and difficulty walking. As ever, it is recommended that you consult a doctor if you are concerned that you might have a deficiency, as they will be able to advise you on the best course of action. 

How much B12 do you need per day? 

The Recommended Daily Amount of B12 is between 250 – 500 mcg per day for adults. Vivo Life’s liquid B12 supplement contains 500mcg per serving of the three most active forms of B12: Methylcobalamin, Hydroxocobalamin and Adenosylcobalamin. Try saying any of those 10 times fast! 

What happens if you have too much B12? 

Whilst B12 has a very low toxicity, and large amounts are not considered dangerous, a consistently elevated presence of B12 can be an indicator that something in the body isn’t right. This can be an early onset warning of diabetes, liver disease or leukaemia. 

But don’t worry if you accidentally take a supplement twice a day, your body excretes whatever B12 isn’t used or needed -  so there’s nothing to worry about there!

In essence, a regular supplement of B12 is one of the best things we can do for our body, so it’s definitely best to keep on top of it!