Are you frequently feeling more tired despite getting a full night's sleep? Or maybe you are finding it difficult to concentrate at work? A lack of an essential vitamin could be to blame. Vitamin B12, though small in the daily requirement, can have a big impact on our bodies when it’s lacking. In this guide, we will explore everything you need to know about B12, from what it is and what it does to deficiency symptoms and how you can choose the right supplement for you.
What is Vitamin B12?
Vitamin B12, the unsung hero of the vitamin world. Also known as cobalamin, this water-soluble powerhouse is essential for making healthy red blood cells, supporting your nervous system in staying sharp, and aiding in the production of energy. If you are feeling foggy and tired, you could be low in vitamin B12, and it may be a good time to examine your intake. Whether you’re sitting at a desk all day like a human-shaped potato or running around like you’re training for the Olympics, low energy is a common struggle. Don’t let fatigue cramp your style, keep an eye on vitamin B12 - because nothing says ‘I’ve got my life together’ like prioritising your B12 requirements, instead of justifying another cup of coffee!
What does Vitamin B12 do?
Energy Release
B12 vitamins are one of the key players in your body’s energy release squad. It can support the metabolism of the food you eat into fuel. So, if the fatigue is hitting you hard, perhaps it is time to take on some additional vitamin B12.
Red Blood Cell Formation
Vitamin B12 is a superstar when it comes to supporting red blood cell production - helping your body in making a healthy and efficient oxygen taxi service.
Nervous System Support
B12 vitamins help keep your nervous system and psychological function in check, through supporting the production of myelin (1), which outlines and protects the nerve cells. Plus, evidence suggests that it can help to regenerate nerve fibres and may pitch in to help maintain nerve health (2).
Immune Support
It isn’t just about energy support, vitamin B12 also supports your immune response. T Cells and natural killer (NK) cells are your body’s defensive line, and vitamin B12 helps to make these into elite soldiers. B12 plays a role in supporting the cell cycle and DNA formation of NK cells and is also crucial for cranking out T lymphocytes and keeping the balance between CD4+ and CD8+ T cells in check.
How much Vitamin B12 per day?
So, what contains vitamin B12? Cheese lovers and egg enthusiasts, you are sitting on a B12 goldmine! This nutrient can be found in all the classic favourites: meats, fish, and dairy. The NHS recommends that adults need 1.5 micrograms of vitamin B12 a day, which can be easily obtained from one boiled egg or a 500ml glass of fresh cow’s milk (3). However, many individuals may need a little more B12 than the average person.
Evidence suggests that people following a vegan diet may be obtaining just 0 to 0.25?g of B12 daily (4). If you are embracing a plant-based diet, there’s no need to panic as you can also find this B vitamin in a reliable supplement or in fortified foods.
Let’s not forget some of the other contenders in the B12 lineup (3):
- Chicken: Clucking in at around 49µg per 100g (with one chicken breast usually weighing around 150g), this poultry powerhouse is a delicious way to boost your vitamin B12 levels!
- Cheddar Cheese: With around 1.5µg of vitamin B12 per 100g, this cheesy delight proves that even your favourite snack can contribute to your B12 intake.
- Salmon: Swimming in nutrients, 100g of salmon (aroundwidely one fillet) packs around 5µg of vitamin B12.
- Sardines: At around 28µg of vitamin B12 per 100g (with one serving weighing around 140g), these little guys pack a punch.
What are some symptoms of vitamin B12 deficiency?
Let’s talk about B12 deficiency, shall we?
When your body is low in vitamin B12, problems can start appearing, including the production of abnormally large red blood cells that just can’t do their jobs. Red blood cells are supposed to carry oxygen around the body using a handy substance called haemoglobin, but when they are not up to par, things can get a little chaotic.
Changes in red blood cells, or low red blood cell count, is where the anaemia comes into play. But here’s the kicker: not all B12 deficiencies lead to anaemia – and even without the full-blown diagnosis, you may still feel offish.
Red Flags That Your Body May Need Some B12
Physical symptoms can be your body’s way of giving you a friendly nudge to pay some attention to it... Here are some signs to keep an eye out for, as described on the NHS website (5), which may be signalling that your body is low in vitamin B12:
- Shortness of breath
- Feeling fatigued or having low energy
- Persistent headaches
- Digestive troubles, such as indigestion or diarrhoea
- Vision problems
- Inflamed tongue (red or with ulcers)
- Muscle weakness
- Problems with cognition, such as memory
- Psychological problems, such as anxiety or confusion
Please note: If these symptoms are new or persist, please contact your healthcare provider.
Who is at risk of B12 deficiency?
So, what causes this deficiency? Sure, it could just be that you’re not eating enough B12, but it also could be due to issues relating to absorption. Factors like gut health problems or indulging in a bit too much alcohol can also play a role in this.
When it comes to B12 deficiency and anaemia, gut absorption issues are the real troublemakers. You may have come across the term 'pernicious anaemia', the primary condition associated with vitamin B12 deficiency.
Pernicious anaemia is an autoimmune condition, which means your immune system is basically throwing a tantrum and attacking its own cells. This condition targets the stomach cells that produce a protein called intrinsic factor. Without intrinsic factor, your body can’t absorb B12, leaving you in a bit of a pickle when it comes to getting those essential nutrients.
If you find out you have pernicious anaemia, your doctor might prescribe intramuscular injections of B12 to make sure your body gets all the good stuff it needs straight to the source.
What else might put you at a higher risk of B12 deficiency? Let’s break it down:
- Age: As we get older, our bodies can become a bit stubborn and may struggle to absorb B12 due to changes in stomach acid. Reduced hydrochloric acid can keep B12 locked up in food, making it harder to release and absorb (5).
- Medications: Some medications, such as metformin commonly taken for Type 2 diabetes, or medicines for indigestion, can limit the absorption of B12 through a few sneaky ways. This includes possibly inhibiting receptors of B12 in the ileum (6).
- Following a vegan diet: If you’re living a vegan life, you might find it tricky to get enough vitamin B12 from your meals.
- Gut conditions: Conditions like Crohn’s disease (a type of inflammatory bowel disease) can throw a wrench in the works, making it harder for your body to soak up vitamin B12 (6).
But don’t fret, there is plenty of evidence showing that oral B12 supplementation can help tackle these issues and get you back on track (7).
How to choose the right vitamin B12 supplement for you
Choosing the right vitamin B12 supplement is like picking the perfect outfit - you want something that fits just right and makes you feel fabulous! Here are some key points to consider to help you strut your way to the best B12 option:
- Choosing the Dosage: If you have been formally diagnosed with a B12 deficiency, aim for a higher dose, like 1000µg once a day. Or if you are looking for a little extra support, for example you are following a vegan diet, around 50-100µg might just be the ticket. Hint: your multivitamin may provide a good level of vitamin B12 for you already.
- Sometimes Less is More: If you are already taking a multivitamin, or a B complex, you may not need a high dose B12 supplement on top of that. Just aim to keep your total B12 supplement intake under 2000µg - because moderation is key.
- Form Matters: B12 vitamins are often found in two different forms, cyanocobalamin and methylcobalamin. Methylcobalamin is often regarded as the more bioavailable option, making it a better fit for those aiming to address specific issues and deficiencies. If you’re looking to target a particular concern, this is the B12 you want in your toolkit!
Final Thoughts
So, there you have it! Vitamin B12 is a little powerhouse that plays a big role in keeping you energised, your nervous system sharp, and your immune system ready to fight off invaders. Whether you are living that plant-based life, or are a meat lover, it is important to keep those B12 levels in check, as low intake may not be the only thing holding you back. If you suspect you may be running low, don’t hesitate to explore your options - whether that’s through food, supplements, or checking in with a healthcare provider. After all, another cup of coffee may not be the only way forward in supporting your fatigue.
To learn more about how you can support your nutrient intake, why not check out our dedicated health blogs? Alternatively, you can contact our expert Nutrition Advice team who are on hand to provide free and confidential advice.
References
- Green, R., Allen, L., Bjørke-Monsen, A L. et al. (2017) ‘Vitamin B12 Deficiency’, Available at: https://doi.org/10.1038/nrdp.2017.40 (Accessed: 25th March 2025).
- ElSoury, M., Fornasari, B. E., Carta, G., Zen, F., Haastert-Talini, K., Ronchi, G. (2021). ‘The Role of Dietary Nutrients in Peripheral Nerve Regeneration’, International Journal of Molecular Sciences. Available at: https://doi.org/10.3390/ijms22147417 (Accessed: 25th March 2025).
- Paul, A.A & Southgate, D.A.T (1985) The Composition of Foods. New York: Crown Copyright.
- Allen LH. (2008) ‘Causes of Vitamin B12 and Folate Deficiency’, Food and Nutrition Bulletin. Available at: 10.1177/15648265080292S105 (Accessed: 25th March 2025).
- NHS (2023) Vitamin B12 and Folate Deficiency Anaemia: Symptoms. Available at: https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/symptoms/ (Accessed:> 25th March 2025).
- Green, R. & Miller, J. W. (2022) ‘Vitamin B12 Deficiency’, Vitamins and Hormones, vol 119, p.405-439. Available at: https://doi.org/10.1016/bs.vh.2022.02.003 (Accessed: 25th March 2025).
- Guéant, J. L., Guéant-Rodriguez, R. M., & Alpers, D. H. (2022). ‘Vitamin B12 absorption and malabsorption’, Vitamins and hormones, vol 119, p. 241–274. Available at: https://doi.org/10.1016/bs.vh.2022.01.016 (Accessed: 25th March 2025).
