Vitamin B12 Deficiency: Symptoms, Testing, and Treatment - A Complete Guide for UK Patients

Vitamin B12 is an essential nutrient that keeps your nervous system healthy, helps your body produce red blood cells, and plays a key role in energy, mood, and cognitive function. Despite its importance, Vitamin B12 deficiency is relatively common in the UK, especially among older adults, people with digestive conditions, and those following plant based diets.

This guide explains what Vitamin B12 does, how deficiency develops, symptoms to look out for, when testing is recommended, and how treatment works based on NHS and NICE CKS guidance (references provided).

What Does Vitamin B12 Do?

Vitamin B12 (cobalamin) supports a range of essential functions:

• Maintaining a healthy nervous system

• Producing red blood cells

• Supporting memory, concentration, and brain function

• Helping form DNA

• Converting food into energy

Because the body cannot make Vitamin B12, we must obtain it from diet or supplements. Good dietary sources include meat, fish, dairy, and eggs, while many plant based foods are fortified with B12.

What Causes Vitamin B12 Deficiency?

NHS guidance identifies the following common causes:

1. Pernicious Anaemia

The most common cause in the UK. This autoimmune condition prevents the body from producing intrinsic factor, a protein needed to absorb B12.Even with a healthy diet, B12 absorption becomes severely impaired. NICE recommends lifelong treatment in these cases.

2. Dietary Deficiency

More common in:

• Vegans

• Some vegetarians

• Individuals with low intake of animal products

NHS advises people on plant-based diets to take B12 supplements or consume fortified foods.

3. Malabsorption Conditions

Digestive conditions that reduce B12 absorption include:

• Coeliac disease

• Crohn’s disease

• Atrophic gastritis

• Stomach or bowel surgery (e.g., bariatric surgery)

These conditions affect the stomach or small intestine, where B12 is absorbed.

4. Medications That Affect Absorption

Certain long-term medications can interfere with B12 levels:

• Metformin

• Proton Pump Inhibitors (PPIs) such as omeprazole, lansoprazole

• H2 receptor blockers

NICE CKS acknowledges the link between long-term use and B12 deficiency risk.

5. Age Related Changes

As we age, our stomach produces less acid and intrinsic factor, making B12 absorption less efficient. Older adults may benefit from periodic testing.

Symptoms of Vitamin B12 Deficiency

Symptoms vary depending on severity and how long the deficiency has been present. According to NHS guidance, symptoms can include:

General Symptoms

• Fatigue or low energy

• Feeling faint

• Breathlessness

• Palpitations

• Pale or yellow tinged skin

• Mouth ulcers

• Reduced appetite

Neurological Symptoms

B12 deficiency can affect the nervous system, leading to:

• Pins and needles (paraesthesia)

• Numbness

• Balance problems

• Memory difficulties

• Confusion

• Mood changes including depression

Untreated deficiency may cause permanent nerve damage, highlighting the importance of early diagnosis.

Other Possible Symptoms

• Sore or red tongue (glossitis)

• Vision problems

• Cognitive decline

Fertility issues or pregnancy complications (less common)

When Should You Consider a Vitamin B12 Blood Test?

Testing is recommended for individuals who:

• Have symptoms of deficiency

• Follow a vegan or vegetarian diet

• Have digestive disorders affecting absorption

• Have had gastric or bowel surgery

• Take longterm metformin or PPIs

• Have family history of pernicious anaemia

• Are older adults with new fatigue or memory issues

A typical test includes:

• Vitamin B12 level

• Folate (B9)

• Full blood count (FBC)

• Intrinsic factor antibodies (if pernicious anaemia is suspected)

How Is Vitamin B12 Deficiency Treated?

Treatment depends on the cause and follows NHS & NICE guidance.

1. Vitamin B12 Injections (Hydroxocobalamin)

First line treatment in the UK for:

• Pernicious anaemia

• Malabsorption issues

• Neurological symptoms

• Severe deficiency

Given intramuscularly, often starting with a loading schedule, then maintenance every 2–3 months.

2. Oral Vitamin B12 Supplements

Suitable for:

• Dietary deficiency

• Individuals able to absorb B12 normally

• Mild deficiency

Daily high dose tablets can be effective.

3. Dietary Changes

Increasing B12 naturally through:

• Meat

• Fish

• Eggs

• Dairy

• Fortified cereals and plant milks

Vegetarians and vegans should take B12 supplements regularly.

4. Lifelong Treatment Where Needed

People with pernicious anaemia or longterm malabsorption will require ongoing treatment and monitoring.

Why Early Detection Matters

Early diagnosis helps prevent:

• Permanent nerve damage

• Cognitive decline

• Mobility problems

• Severe anaemia

• Pregnancy-related complications

Vitamin B12 deficiency is usually easy to treat once identified.

When to Seek Medical Advice

Speak to a healthcare professional if you experience:

• Persistent fatigue

• Tingling or numbness

• Memory changes

• Mood changes

• Digestive conditions

• Long-term use of metformin or PPIs

• High-risk dietary patterns

A simple blood test can provide clarity and guide treatment.

References

NHS

• NHS. Vitamin B12 or folate deficiency anaemia – overview, symptoms, causes, diagnosis, treatment.

• NHS. Pernicious anaemia – causes and treatment.

• NHS. Dietary sources of Vitamin B12.

NICE

• NICE Clinical Knowledge Summaries (CKS). Anaemia – B12 and folate deficiency.

• NICE guidance on the management of malabsorption and autoimmune conditions affecting B12.

Disclaimer

This blog is intended for general patient education only and should not be used as a substitute for personalised medical advice, diagnosis, or treatment. Patients experiencing symptoms or concerns related to Vitamin B12 deficiency should consult their GP, supervising clinician, or a qualified healthcare provider for assessment and personalized guidance.