Vitamin B12 Benefits – and Symptoms of Deficiency

Vitamin B12 Symptoms of Deficiency

What do you know about Vitamin B12?

I didn’t know much about it before I studied nutrition. I knew B12 was something you got from animal foods, so vegetarians and vegans might be deficient, but not much else.

And it seems Vitamin B12 often gets ignored in the medical world too. 

My grandma was in and out of psychiatric hospitals for years. She used to go a bit ‘crazy’ they said once in a while and spend a few months in an institution. Until they discovered years later that she was B12 deficient. Imagine her life had they discovered this earlier?

And my mum also has Pernicious Anaemia, so I get tested every year to make sure I’m OK, as it's clearly in the family.

What does Vitamin B12 do?

  • Produces healthy red blood cells that transport oxygen and nutrients around the body
  • Helps make DNA
  • Vital for heart health
  • Vital for brain function and nervous system – it helps make myelin, the protective layer over all our nerves
  • Helps make energy
  • Helps to break down excess hormones like oestrogen

Common symptoms of B12 deficiency

  • Fatigue – Vitamin B12 is needed for the production of red blood cells, if you don’t have enough it can affect oxygen transport to your cells, making you exhausted.
  • Dizziness – if you feel wobbly when you get up too fast or you feel dizzy going upstairs or vertigo/balance problems – it could be your B12 stores are low
  • Brain fog & memory loss – it might not be dementia or Alzheimers, it could be b12 deficiency
  • Pins & needles – or numbness in your hands or feet, is another common symptom.
  • Clumsiness and confusion
  • Mood swings, irritability, frustration
  • Blurred vision – or spots in front of your eyes, light sensitive or shadows
  • Dry skin, brittle nails with ridges
  • Swollen or sore tongue
  • Shortage of breath – sighing regularly (the sighs)

So it's easy to miss, because symptoms are common ones like fatigue, aches and pains, mood issues, depression, anxiety, forgetfulness and brain fog – similar symptoms to getting older!

And if you’re depressed, you may be given anti-depressants rather than your B12 levels tested.

Long term deficiency can damage your nerves, risking paralysis and severe cognitive function.

There is a comprehensive Symptoms Checklist available on the homepage of the Pernicious Anaemia Society that is free to download – it’s part of the Society’s campaign to get these early indicators of B12 deficiency more widely known among patients and medical professionals.

Types of Vitamin B12 Deficiency

  1. Pernicious Anaemia – this is an auto immune condition where you lack a protein called Intrinsic Factor that your body produces to absorb B12 from your food. People with PA don’t produce Intrinsic Factor at all, we don’t know why but they have antibodies against it. Supplements are pretty useless as they cant absorb them, so they generally need injections.
  2. B12 deficiency – this is where you have Intrinsic Factor but you are not getting enough B12 for other reasons including;
    • Diet – Vitamin B12 can only be found in animal foods, so vegans and vegetarians are particularly at risk (studies show that 50% of long term vegetarians, and 80% of vegans could be deficient)
    • Alcohol and medications such as PPI’s, acid suppressors, and Metformin are also risks for deficiency
    • Poor digestion, including;
      • Low stomach acid or gastritis
      • IBS, Crohns, Ulcerative Colitis
      • Leaky gut or inflammation
      • Dysbiosis – underlying infection or imbalance in gut flora

So even if your diet is rich in B12 foods, you may not be absorbing it. We get worse at this as we get older, as our digestive juices get depleted. It’s thought amongst experts that around 40% of those over 60 could have B12 deficiency.


  • As routine testing is not often done, and symptoms can often mimic other conditions like depression or anaemia, diagnosis can be missed.
  • The reference range is very large, meaning that low levels are often classed as normal, whereas many experts believe you can have symptoms at higher levels.
  • The current blood test doesn’t distinguish between the inactive and active forms of B12. It just measures your total levels. So if your blood levels are ‘normal’ there’s no way of knowing if this is active B12.

Treatment Options

If you have Pernicious Anaemia, you will need injections of B12 which you should get on the NHS or your health provider in your country.

If you don’t have PA but are B12 deficient, then eating B12 rich foods (like red meat, liver, fish, dairy, eggs) or supplementation is recommended. Methylcobalamin is the most effective form of supplement, and sublingual tablets have good results. Some clinics offer IV infusions too.

So if you have any of the symptoms I have listed, or you’re over 60, my advice would be to;

  • Get your Active B12 levels tested (holotranscobalamin) – plus folate and ferritin levels
  • If deficient, identify the root cause – is it PA or just deficiency?
  • Then either get injections through your Doctor, or increase levels through diet and/or supplements

If you’d like to talk to us about testing your active B12 or our other health tests, please CONTACT US for more information.

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