Vitamin B12 deficiency happens when your body isn’t getting or absorbing enough of a specific B vitamin (B12) from diet alone. This then causes the body not to have enough red blood cells to carry oxygen around the body, keeping us well, functioning and healthy.
Usually found in animal produce (dairy, eggs, meat), vegetarians and vegans are particularly prone to B12 deficiency but it can affect anyone, causing tiredness, fatigue and even cognitive changes in some cases.
Luckily, it is easily treated with dietary changes, supplements and even injections, depending on the cause and severity of your condition.
From the B12 deficiency symptoms to look out for to what type of treatment could benefit you, here’s everything you need to know.
What Is Vitamin B12?
Vitamin B12 is important for the function of your nerves and for the production of the DNA and RNA in your cells.
Vitamin B12 is one of eight B vitamins. It is responsible for neurological function, producing DNA, maintaining a healthy nervous system and generating red blood cells, which carry oxygen around your body. It helps reduce tiredness and fatigue.
Vitamin B12 is naturally produced when the body breaks down food sources and, via enzyme activity, takes it up into the bloodstream.
It can exist in several different forms including:
- Methylcobalamin – an active form ready to be absorbed by the body.
- Hydroxocobalamin – a manufactured form of B12 often used in prescription injections because it stays in the body longer.
- Cyanocobalamin – a manufactured form usually used for dietary supplements.
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Signs and Symptoms of Vitamin B12 Deficiency
Vitamin B12 deficiency anaemia occurs when a lack of vitamin B12 or folate causes the body to produce abnormally large red blood cells that can’t function properly.
When you’re B12 deficient you may experience physical symptoms, neurological symptoms and more.
From tiredness to here’s what to look out for and to see your doctor about if they get worse or are affecting day to day life.
Physical symptoms of vitamin B12 deficiency
According to the NHS, symptoms of B12 deficiency may include:
- rapid breathing
- shortness of breath
- headaches
- indigestion
- loss of appetite
- palpitations
- vision problems
- feeling weak or tired
- diarrhoea
- a sore or red tongue, sometimes with mouth ulcers
- problems with memory, understanding and judgement (cognitive changes).
Neurological symptoms of vitamin B12 deficiency
Other symptoms may include: strange sensations, numbness, or tingling in the hands, legs, or feet. difficulty walking.
Neurological symptoms affecting your brain and nervous system can include:
- numbness
- muscle weakness
- problems with balance and coordination
- pins and needles
- incontinence. (Source: NHS)
Potential other symptoms of vitamin B12 deficiency
Other symptoms can include psychological problems such as:
- mild depression
- feeling irritable
- anxiety
- confusion and dementia.
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Vitamin B12 Deficiency Treatments
There are two common ways to treat B12 deficiency; B12 injections and B12 supplements. Which you will need will depend on what’s causing your deficiency and how bad your symptoms are as a result.
If your symptoms are mild and your deficiency is diet-related you could try supplements. However, if your body does not absorb B12 for some reason then you will need injections.
If your doctor recommends a particular treatment you may need follow-up blood tests to check your B12 levels are responding and improving.
Vitamin B12 Injections
Vitamin B12 supplements are usually given by injection at first.
B12 via injection will contain hydroxocobalamin, a manufactured form of the vitamin, which will be administered by a doctor or nurse directly into the muscle (usually your arm). They may be free or require a prescription charge depending on where you live.
How often you’ll need the injections will depend on blood test results and how well your B12 levels recover.
You may begin by needing them a few times a week but this could reduce to every few months.
If you are having injections to treat pernicious anaemia then you will need these injections for life.
There is no benefit to having B12 injections if your levels are already normal.
Vitamin B12 Supplements
One of the most common ways to try and top up vitamin B12 levels is by taking supplements, explains ZoomDoc GP, Dr Michael Prudden.
‘If you don’t eat much meat or animal produce it’s sensible to take vitamin B12 tablets daily, particularly if you are vegan,’ he says.
‘However, if you have B12 deficiency symptoms it is worth talking to your doctor and getting properly tested so that the cause of your condition is properly diagnosed and treated.
‘Simply taking a daily supplement may not be the right course of treatment for you.’
Causes of Vitamin B12 Deficiency
Identifying the cause of vitamin B12 deficiency is key to being able to treat it with the right approach – as well as ruling out anything else that may be causing it.
Common causes are either diet-related, for example, not eating or liking meat or following a vegetarian, vegan or other restrictive diet or caused by lifestyle choices or circumstances, such as:
- medication (such as diabetes medicine)
- alcohol consumption
- pregnancy.
Or it can be caused by illnesses or conditions such as:
- pernicious anaemia
- immune system disorders.
Here’s a look into some of the key causes.
Low Vitamin B12 due to Medication
Certain medicines can reduce the amount of vitamin B12 in your body. This can include:
- Proton pump inhibitors (PPIs) – to treat stomach acid or reflux.
- Metformin – for diabetes and PCOS.
- Nitrous oxide – for sedation or pain relief in labour.
Your doctor will be able to advise the best course of action to increase your B12 levels.
Low Vitamin B12 due to Drinking Too Much Alcohol
Consumption of alcohol affects the level of B12 absorption in the body even if taken in moderate amounts.
Regular alcohol consumption has a number of health drawbacks, including impacting sleep, causing weight gain, affecting mood and there is also evidence it has nutritional disadvantages, too.
‘If you drink regularly, or drink too much regularly, it’s worth talking to your doctor about the impact this is having on your health,’ says Dr Michael.
‘If you suspect it is causing a B12 deficiency your doctor will be able to test for this, but will also recommend you cut down on or stop drinking alcohol in order to benefit from B12 injections, if this is the recommended treatment,’ he says.
Vitamin B12 and Pregnancy
It should be possible to get enough B12 through a balanced and varied diet. However, if you follow a restricted diet or are vegetarian or vegan, talk to your doctor or midwife about your B12 levels.
The only supplements all pregnant women need to take are:
- 400 micrograms of folic acid every day before you’re pregnant and until you’re 12 weeks pregnant. In some instances you may need to take a higher dose but your doctor or midwife will advise.
- 10 micrograms of vitamin D each day between September and March.
Pernicious Anaemia and Vitamin B12
Immune system disorders, such as pernicious anaemia – an autoimmune disease – can make it harder or impossible for your body to absorb vitamin B12, even if you’re eating plenty of B12-rich sources or are taking supplements.
‘If your body cannot absorb B12, no matter how much you eat or take as a supplement will help. This is a common cause of the condition and requires regular injections of a particular form of B12 called hydroxocobalamin,’ says Dr Michael.
Intestinal Malabsorption and Vitamin B12
Other conditions that affect your intestines or stomach lining, such as Crohn’s disease, Celiac disease or gastritis can, in a nutshell, stop your body being able to absorb vitamin B12.
‘As your vitamin B12 deficiency is not caused by a lack of vitamin B12 in your diet, you’ll probably need to have an injection of hydroxocobalamin every 2 to 3 months for the rest of your life,’ says Dr Michael.
A Vegan Diet and Vitamin B12
Individuals who adhere to a vegan and vegetarian diet since birth show higher rates of vitamin B12 deficiency.
As most sources of vitamin B12 can be found in meat, eggs and dairy produce, vegans will struggle to get enough into their diet through plant-based products.
Some fortified foods contain B12, such as plant-based milk drinks, yeast extract (Marmite) but the NHS says ‘sources for vegans are limited and a vitamin B12 supplement may be needed.’
The British Dietetic Association (BDA) recommends the following advice:
‘Long-term vegetarians and vegans should have their vitamin B12 status checked, especially as high folate levels can mask vitamin B12 deficiency, encouraged to consume B12 fortified foods and if required, recommended supplements of around 10 mcg per day to ensure adequate status.’
‘Always check in with your doctor if you are vegan and are concerned about your B12 levels,’ says Dr Michael.
Other reasons for Vitamin B12 Deficiency
Other reasons you may have a vitamin B12 deficiency include:
- Functional vitamin B12 deficiency – a problem with proteins that help transport vitamin B12 from cell to cell.
- Transcobalamin II deficiency – a rare genetic disorder.
- Gastric surgery – such as a gastric bypass can impact vitamin B12 absorption.
How to prevent Vitamin B12 Deficiency
Although eating B12-rich sources of food (red meat, fish, poultry, eggs, milk and dairy produce) can be a simple way to prevent becoming deficient, it may not be enough.
Other ways to prevent B12 deficiency include:
- Finding fortified foods to eat more of – such as breakfast cereals, nutritional yeast, plant milk and bread.
- Taking daily B12 supplements – ask your doctor or even pharmacist to help you choose which supplement is best for you.
- Cut down on alcohol – drinking alcohol can make it harder for your digestive system to absorb vitamin B12.
- Manage your condition – if you have a digestive disease make sure you follow a healthy lifestyle and take medication as guided.
Can you overdose on Vitamin B12?
Vitamin B12 is generally considered to be safe even in larger quantities because your body cannot store excess amounts.
Although it’s hard to take too much via dietary sources alone, it is possible to take an excess through supplements.
NHS guidance on vitamin B12 says ‘there’s not enough evidence to show what the effects may be of taking high doses of vitamin B12 supplements each day,’ and therefore you should not take more than has been advised by your doctor.
NHS advice adds that ‘taking 2mg or less a day of vitamin B12 in supplements is unlikely to cause any harm.’
What are the Benefits of Vitamin B12?
Besides taking care of the body’s growth, it helps a person to stay sharp and fight off diseases.
Vitamin B12 can have many benefits when your levels are normal. However, taking it on top of normal levels won’t benefit you.
The only evidence around B12 shows that vitamin B12 benefits us by:
- making red blood cells
- keeping the nervous system healthy
- releasing energy from food
- working together with folate (vitamin B9).
There is no evidence to suggest vitamin B12 can affect skin, hair or nails.
How Vitamin B12 can affect energy
If you are deficient in vitamin B12 you may feel tired or even exhausted a lot of the time.
Once this is replenished, in a way that your body can absorb it, you should notice better energy levels.
It is inaccurate to say that vitamin B12 gives you energy, but it does help to reduce tiredness and fatigue.
How Vitamin B12 can affect vision
B12 deficiency can cause vision problems such as blurriness, loss of vision and blind spots.
This happens when the optic nerve gets damaged but is a rare symptom of the condition.
How Vitamin B12 can affect Memory
More research is required in terms of exactly how vitamin B12 affects memory.
Some evidence suggests B12 can improve cognitive problems (thought process, learning etc) but there is also evidence to suggest it makes no impact.
How Vitamin B12 can affect Red Blood Cells
B12 aids in the production and regeneration of red blood cells, a key reaction in the body.
Without B12 we can become deficient and even anaemic causing long-term health complications.
How Vitamin B12 can affect Depression
Although there are links between low levels of B12 and depression, this does not mean that B12 can treat or cure depression.
Vitamin B12 Dosages – how much should you get?
In terms of recommended daily amounts, the NHS recommends adults ‘need about 1.5 micrograms a day.’
This should be achievable through diet alone if you eat meat, fish and dairy foods.
If you require a supplement, the amount you should take will depend on whether it is a diet-related deficiency or not.
The NHS recommends the following:
- For diet-related deficiency – 50 micrograms to 150 micrograms, taken once a day
- For B12 deficiency not caused by your diet – 1-2 1,000 microgram tablets, taken once or twice a day (unless you are prescribed vitamin B12 injections.)
What are good sources of Vitamin B12?
Good sources of vitamin B12. Good sources include: meat; fish; milk; cheese; eggs; some fortified breakfast cereals.
Good sources of B12 include:
- red meat and poultry
- shellfish (oysters)
- salmon and cod
- milk and other dairy products
- eggs
- fortified foods (yeast extracts, breakfast cereals, bread).
When to see a GP for a B12 Deficiency – getting diagnosed
If you are concerned about your B12 levels or are affected by any B12 deficiency symptoms, talk to your doctor about getting tested, diagnosed and treated.
Your GP will be able to diagnose you based on symptoms, although a blood test may be required.
Or you can do an at-home test. ZoomDoc finger prick blood tests are as accurate as tests you would normally take via a normal regular blood test at hospital or in a GP setting.
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Frequently Asked Questions
Which food is highest in B12?
Pan-fried beef liver gets you about 70mcg per serving, followed by clams (17mcg) and oysters (15mcg)
What is the fastest way to fix B12 deficiency?
Either by adjusting your diet to include more animal produce – or by taking B12 supplements or getting injections.
What are the four stages of B12 deficiency?
Stage 1: lower levels of vitamin B12 in your blood.
Stage 2: low levels of vitamin B12 in your cells along with metabolic abnormalities.
Stage 3: neurological and psychological symptoms such as anxiety, confusion, problems with balance may appear.
Stage 4: macrocytic anaemia – very large red blood cells.
Should I be worried if my B12 is low?
Vitamin B12 deficiency can cause complications if it is not treated. There is no need to be worried as long as you see a doctor and start treatment.
Why isn’t my body absorbing B12?
Lifestyle habits (drinking alcohol or taking certain medication) or digestive issues can make it harder for your body to absorb vitamin B12 over time.
Can low B12 cause weight gain?
Weight gain is unlikely to be a direct symptom of low B12. However, if you have low energy or mood and stop exercising or start binge eating you will be more likely to put on weight.
What organ is affected by B12 deficiency?
Once you become anaemic (low on red blood cells) your tissues and main organs won’t get enough oxygen.
What are the facial signs of B12 deficiency?
You may notice pale or yellowing skin if you are low in B12.
What happens if your B12 stays low?
If a B12 deficiency is left untreated or does not respond to treatment, it can cause physical, neurological and psychological symptoms and even heart failure.
What causes B12 deficiency in adults?
Regularly not eating a diet rich in vitamin B12 (via dairy, meat and eggs) will cause a deficiency. Some conditions that affect the body being able to absorb vitamin B12 will also cause this.
What foods should be avoided if you have B12 deficiency?
It can be a good idea to limit or avoid alcohol.
How long does it take to recover from vitamin B12 deficiency?
Once you begin treatment for vitamin B12 deficiency, it can take 6-12 months to recover. You may not notice any improvement for at least a few months of starting B12 injections.
How common is vitamin B12 deficiency?
Quite common. Vitamin B12 deficiency affects around 12.5% of all adults. In the UK, the NHS says it is more common in older people, ‘affecting around 1 in 10 people aged 75 or over and 1 in 20 people aged 65 to 74.’
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