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What is Vitamin B12 and why is it so important?

woman jumping on her bed full of energy
Vitamin B12 is one of the 8 B vitamins that play a vital role in keeping our bodies in tip-top condition. 
From reducing fatigue and looking after our body’s nervous system and red blood cells, find out more about what vitamin B12 is, and why it is so important for your body.

What is vitamin B12? 

Vitamin B12 is a water-soluble nutrient that has several different roles in keeping your body healthy. All B vitamins, like folic acid and niacin, are important for helping your body convert food into energy, but B12 plays a key role in various other bodily functions too.1

It's a vitamin that is naturally present in a lot of foods as it is bound to protein in many different types of food, but as it is water soluble, it dissolves when in contact with water in your body. So, we need to eat enough every day as your body can’t store or make it.2

You’ll find vitamin B12 as a supplement in various forms too, although it can be labelled with different names. Cyanocobalamin is the man-made form of vitamin B12 and can be listed on B12 supplements.3

Vitamin B12 sources

As your body doesn’t make or store vitamin B12, it’s important to get enough through your diet. Animal products like beef, pork, eggs, milk, cheese, and fish are all great sources of vitamin B12.4

However, if you're vegetarian or vegan, it may be that you aren’t able to get enough vitamin B12 as animal products are excluded from your diet.5

Vitamin B12 can sometimes be found in fortified breakfast cereals and nutritional yeast, but for vegans and vegetarians, this might not be enough. It’s worth speaking to your GP about alternative ways you can get enough vitamin B12 if you’re vegan or vegetarian, to make sure you don’t develop a vitamin B12 deficiency. 

What happens if you don’t get enough vitamin B12?

The NHS recommends adults consume at least 1.5mcg of vitamin B12 a day, which can be easy if you eat enough vitamin B12 rich foods. If you can’t reach these levels, you could be at risk of developing a deficiency.

Low B12 symptoms can include:7
  • Tiredness 
  • Headaches 
  • Palpitations 
  • Loss of appetite 
  • Sore red tongue 

You can check your vitamin B12 levels at home with an at-home testing kit. While at-home tests shouldn’t replace seeing your doctor for any concerns, they can help you better understand your health and get proactive about your well-being. It is essential to note that these home tests can’t give you a diagnosis, so for any concerns, you should always discuss your results with your GP. They can provide you with any help and advice you may need. 

Handpicked content: How to test your B12 levels

Why is vitamin B12 important? 

1. Energy 

One of vitamin B12’s main roles is to help with the production and development of red blood cells that carry oxygen around our bodies.8

Oxygen travels from your lungs into the blood and flows to all your vital organs: the brain, lungs, and muscles.9  If these organs do not receive enough oxygen, they’ll slow down, and you can find yourself feeling fatigued.

Not getting enough B12 can lead to vitamin B12-deficiency anaemia. This is where your body can’t make enough healthy red blood cells due to a lack of vitamin B12.10

 2. Stress 

B vitamins, like B12, are thought to be beneficial when it comes to tackling stress. Vitamin B12 is essential for brain function and development as well as producing melatonin and serotonin, which are important for your mood and sleep.11

Stress can affect your body in many ways, with one being that it can significantly affect your nervous system.12 Your nervous system plays a major role in almost every aspect of your health and well-being, from breathing to thinking, and many other complex processes.13

Some studies suggest that Vitamin B12 contributes to the healthy functioning of the nervous system, and it may aid in reducing the effects of stress and anxiety on the body.14,15

 3. Bone health 

Vitamin B12 is thought to be linked to keeping your bones strong and healthy, too. In some studies, researchers found that older women with low levels of vitamin B12 experienced bone loss faster than those with higher vitamin B12 levels.16

However, the research into vitamin B12 and bone health is limited, so more studies are needed for definitive results.17

 4. Skin, hair & nails 

As vitamin B12 plays an important role in cell production, it has been shown to be an essential vitamin for keeping your hair, skin, and nails healthy.18

Some research shows that a lack of vitamin B12 can cause your hair to change and your nails to become weaker and more brittle.19  But, if you’re not deficient in vitamin B12, there’s not enough research to understand whether taking a B12 supplement will have an effect on your skin, hair and nails. 

The final say

Vitamin B12 is a crucial nutrient that plays a significant role in various processes in your body, like aiding in the production of red blood cells and DNA synthesis.

But, maintaining adequate levels of vitamin B12 can be a struggle as it is mainly found in animal products like meat, cheese, and eggs. So, for those who follow a vegan or vegetarian diet taking a supplement may be necessary.


1.       https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

2.       https://ods.od.nih.gov/factsheets/VitaminB12-Consumer/

3.       https://www.nhs.uk/medicines/cyanocobalamin/

4.       https://journals.sagepub.com/doi/abs/10.3181/0703-MR-67

5.       https://www.cambridge.org/core/journals/proceedings-of-the-nutrition-society/article/health-effects-of-vegetarian-and-vegan-diets/1B1F779BC279BE2F632C48F5BDB4DF64

6.       https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-b/

7.       https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/symptoms/

8.       https://www.sciencedirect.com/science/article/abs/pii/S1359511323000363

9.       https://www.redcrossblood.org/local-homepage/news/article/function-of-blood-cells.html

10.    https://www.nhlbi.nih.gov/health/anemia/vitamin-b12-deficiency-anemia

11.    https://pubmed.ncbi.nlm.nih.gov/8914118/

12.    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579396/

13.    https://www.nichd.nih.gov/health/topics/neuro/conditioninfo/functions

14.    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6491933/

15.    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9190671/

16.    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5734110/

17.    https://pubmed.ncbi.nlm.nih.gov/34116377/

18.    https://pubmed.ncbi.nlm.nih.gov/31144371/

19.    https://pubmed.ncbi.nlm.nih.gov/25559140/

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