Vitamin B12 for Vegans | What is it & Why do Vegans Need it?

One of the most common arguments against vegan diets is that you might be missing out on key nutritionals. The truth is, it can actually be easier to consume the vitamins and minerals you need due the variety of fruits, vegetables, and grains found in a typical plant-based diet. There is, however, one vitamin which is commonly lacking in a vegan diet which can have significant impact on health – vitamin B12.

What is vitamin B12?

Vitamin B12, also known as cobalamin, is an essential water-soluble vitamin which is important for the normal functioning of the body. Not only is it the largest and most complex vitamin structurally, but it is vital for important processes such as cell metabolism and red blood cell formation.

As an essential vitamin, it must be consumed through the diet; this is where vegans can miss out.

Whilst humans and other animals can produce vitamin B12 through bacteria in the gut, humans cannot absorb it as it is synthesized in the lower portion of the gut (colon), below the small intestine where nutrients are mainly absorbed. This means you have to eat sources of vitamin B12 in order to give the body the essential micronutrient it needs.

Unfortunately for vegans, most natural sources of vitamin B12 come in the form of animal products such as red meat, fish, poultry, and dairy products. If you follow a strict vegan diet, or have even just reduced your consumption of animal products, this could mean you are likely deficient in B12.

vitamin B12 tablets

What are the benefits of vitamin B12?

You may be familiar with vitamin C from oranges helping to boost your immune system, or vitamin D – the “sunshine vitamin” – supporting strong and healthy bones, but what exactly does vitamin B12 do?

Vitamin B12 is responsible for a wide range of important functions in the body including cell division and metabolism.

It can also help to reduce tiredness and fatigue, so if you find you are lacking energy on a vegan diet it might be worth considering whether a lack of dietary B12 is the culprit.

This powerful nutrient is known to support neurological and psychological functions, meaning it helps to make sure your brain can work to its full potential and your mood doesn’t plummet either!

Vitamin B12 is also important for the formation of red blood cells which are used to transport oxygen around the body. If vitamin B12 intake is too low, this can cause a type of anaemia where the red blood cells can no longer work correctly which can have a significant impact on overall health.

Why do vegans need vitamin B12? | What are the best sources?

 Vegans and even vegetarians should definitely check whether they are fuelling their bodies with enough vitamin B12, as this is one of the few nutrients which is unfortunately very difficult to eat naturally through plants alone. Most natural sources of vitamin B12 are animal-based, so if you have cut out or reduced the amount of meat and dairy in your diet, then you will need to consciously add vitamin B12 into it from other sources.

According to The Vegan Society1,

The only reliable vegan sources of B12 are foods fortified with B12 (including some plant milks, some soy products and some breakfast cereals) and B12 supplements.

Many vegan products are fortified with synthetic vitamin B12 as it’s difficult to gain enough of the nutrient naturally in plant-based foods. Foods such as cereals, yeast-based products, and vegan spreads can be a good source of vitamin B12, as well as some fortified plant milks like soy milk.

If yeast-based spread like Marmite aren’t for you, then it’s definitely worth considering the easiest option for vegans to get their vitamin B12 – supplements.

Vitamin B12 supplements remain the easiest and most convenient way of ensuring you are getting enough B12 every day. The recommended dosage of vitamin B12 is actually very small, as it is typically absorbed in small amounts. You only need about 1-3μg every day (although this increases as you get older), which is easily achieved through a daily B12 supplement. There are no significant side effects of taking too much vitamin B12 however if you feel any negative effects after taking a supplement be sure to speak to a doctor.

 Chocolate banana overnight oats

What is vitamin B12 deficiency?

Vitamin B12 deficiency is a health condition caused by low levels of vitamin B12 in the body, and can result in unpleasant symptoms such as weakness, tiredness, heart palpitations, and mood changes. As B12 is involved in a range of important physiological processes, being deficient in this important vitamin can affect many aspects of your health.

One of the most important role vitamin B12 plays in the body is in the formation of red blood cells. If B12 levels are too low, red blood cells can’t form properly and instead become abnormally large, preventing them from carrying out their job as oxygen carriers around the body. This can lead to those with vitamin B12 deficiency to be anaemic.

For vegans, vitamin B12 deficiency can be particularly common as B12 is not naturally found within plant-based diets. It is necessary for vegans to consume fortified foods or a B12 supplement in order to get the recommended daily intake.

Both vegans and non-vegans increase their risk of vitamin B12 deficiency as they age, as the ability to absorb the vitamin slows down.

How can you tell if you might have vitamin B12 deficiency? Here are some of the recognised symptoms to watch out for:

  • Persistent tiredness or fatigue
  • Pale or yellow-tinged skin caused by damaged red blood cells releasing a pigment called bilirubin.
  • Heart palpitations
  • Mood changes
  • Breathlessness and dizziness


It’s easy to overlook the importance of vitamin B12, especially as many of the symptoms, such as tiredness, can develop over a few years and so not be attributed to a lack of certain nutrients. Vitamin B12 is extremely important for vegans to take notice of as it is really hard to consume enough from plant-based sources alone. If you don’t consume enough of the vitamin in your diet, you can quickly become deficient which can cause a whole host of negative side effects and even anaemia. The solution, however, couldn’t be easier; vitamin B12 supplements guarantee that you meet the necessary requirements daily. You can eat as much fruit and veg as you like and know you are still getting all of the essential vitamins and minerals you need to be your happiest and healthiest self.

Arabella Ogilvie

Arabella Ogilvie

Writer and expert

Arabella has a Bachelor of Science degree in Physiology from the University of Glasgow where she covered health topics ranging from the physiological effects of exercise and nutrition, to psychology and neuroscience.

She has a lifelong interest in sport and fitness, including running, swimming, hockey, and especially rowing. At university, Arabella was a keen rower and competed in the first boat at events such as the prestigious Henley Women’s Regatta, The Scottish Boat Race, and British University Championships, and won Novice Rower of the year in her first year.

In her spare time, Arabella loves to train in the gym and practice yoga and meditation. She is passionate about the natural world and will take any opportunity to be outdoors.

Find out more about Arabella’s experience here.