Preparing for B12

Overview

Vitamin B12 deficiency means you don't have enough vitamin B12 in your body. B12 helps make red blood cells and keeps your nerves healthy. A blood test can check your B12 level. Preparing for the test usually means telling your doctor about any supplements you take – they may ask you to stop taking them a few days before.

Yes, B12 deficiency is common, especially in older adults and people with certain health conditions.

It most often affects people with pernicious anemia (an autoimmune condition), those who follow a strict vegan or vegetarian diet, people who have had stomach surgery, older adults, and people taking long-term acid-reducing medicines.

Symptoms

Common symptoms

• Feeling very tired and weak
• Pale or yellowish skin
• Numbness, tingling, or pins and needles in hands and feet
• Sore, red tongue or mouth ulcers
• Blurred vision
• Mood changes like depression or irritability

Symptoms in children

• Delayed growth and development
• Weakness and irritability
• Poor appetite
• Trouble moving or walking

Symptoms in older adults

• Confusion and memory problems (sometimes mistaken for dementia)
• Shaky movements or trouble with balance
• Tiredness and weakness

Causes

Main causes

• Pernicious anemia – your immune system attacks cells in your stomach that help absorb B12
• Not getting enough B12 from food (common in vegans and strict vegetarians)
• Problems absorbing B12 due to gut conditions like Crohn's disease, coeliac disease, or after stomach or weight-loss surgery
• Long-term use of medicines such as metformin or proton pump inhibitors (acid reducers)

Risk factors

• Being over 60 years old
• Following a vegan or strict vegetarian diet
• Having had stomach or intestinal surgery
• Having an autoimmune disease (like type 1 diabetes or thyroid disease)
• Taking certain medicines long-term

When to see a doctor

See a doctor urgently if:

• If you have sudden confusion, trouble breathing, chest pain, or vision loss, call your local emergency number immediately.
• If you have severe numbness, weakness, or difficulty walking, seek same-day medical advice.

Book a routine appointment if:

• If you have ongoing tiredness, tingling, or other mild symptoms, book a routine appointment with your doctor.

Diagnosis

Your doctor can order a simple blood test to measure your vitamin B12 level. They may also check your full blood count and look for antibodies that point to pernicious anemia.

Tests that may be done

• Vitamin B12 level blood test
• Full blood count (to check for anemia)
• Intrinsic factor antibody test (if pernicious anemia is suspected)

What to expect at your appointment

A blood sample is taken from a vein in your arm. You do not usually need to fast, but your doctor may ask you to stop taking B12 supplements for a few days before the test to get a clear result. The test itself is quick and causes little discomfort.

Treatment

Treatment aims to restore your B12 levels and address the underlying cause. Most people need lifelong B12 replacement if the deficiency is due to an absorption problem.

Self-care at home

• Eat foods rich in B12: meat, fish, eggs, dairy, and fortified cereals or plant milks if you are vegan.
• If advised by your doctor, take a B12 supplement. Never change your dose without speaking to your healthcare provider.
• Keep a record of your symptoms to track improvement.

Medical treatments

B12 replacement is usually given as an injection into a muscle (intramuscular injection) or as high-dose tablets. The choice depends on the cause and severity. Your doctor will explain the plan that is right for you. For pernicious anemia, injections are typically given every few months for life.

When is surgery considered?

Surgery is not used to treat B12 deficiency itself, but surgery can sometimes be a cause of B12 deficiency (for example, after weight-loss surgery).

Living with this condition

Most people manage B12 deficiency very well with regular treatment. You will need to keep up with scheduled injections or tablets. Your doctor will monitor your levels with occasional blood tests.

Lifestyle tips

• Follow a B12-rich diet as recommended by your healthcare team.
• If you take injections, ask your doctor or nurse to show you how to self-inject if that option is available.
• Wear a medical alert bracelet if you have pernicious anemia, so emergency services know your condition.

Diet and exercise

Eat a balanced diet with B12 sources. If you are vegan, include fortified foods like plant milks, breakfast cereals, and nutritional yeast. Gentle exercise like walking can help with energy levels and overall health.

Mental health and emotional wellbeing

Living with a chronic condition can cause anxiety or low mood. Symptoms like fatigue and memory problems can also affect your mental health. Treatment usually improves these symptoms, and talking to your doctor or a counselor can help.

Prevention

For some people, B12 deficiency can be prevented by eating enough B12-rich foods or taking supplements if needed (for example, if you are vegan). If you have pernicious anemia or an absorption problem, it cannot be prevented, but it can be treated effectively.

Screening programmes

Routine B12 screening is not standard, but doctors may check B12 levels in people at high risk (older adults, vegans, those with gut conditions). If you think you are at risk, talk to your doctor.

Complications

If left untreated

• Pernicious anemia (severe anemia that can cause breathlessness, palpitations, and weakness)
• Nerve damage that can lead to numbness, weakness, and trouble walking (may become permanent)
• Heart problems from anemia
• Vision loss
• Depression and cognitive decline (memory loss, confusion)

Long-term outlook

With early treatment, most symptoms of B12 deficiency improve or resolve. Even long-standing nerve damage can often be partly reversed. The condition is highly treatable, and most people lead full, healthy lives.

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