Vitamin B12 deficiency living patient overview

Overview

Vitamin B12 deficiency means your body does not have enough vitamin B12. Your body needs this vitamin to make red blood cells and keep your nervous system healthy.

Yes, it is fairly common, especially in older adults and people who follow a vegan or vegetarian diet.

It can affect anyone, but it is more common in people who do not eat enough B12-rich foods (vegans, vegetarians), adults over 60, people with digestive conditions (like Crohn’s disease or coeliac disease), and those who have had stomach surgery or take certain long-term medicines for heartburn or diabetes.

Symptoms

Common symptoms

• Feeling very tired and weak
• Pale or yellowish skin
• Shortness of breath, especially when active
• Pins and needles or numbness in hands and feet
• Poor balance and unsteady walking
• Memory problems or confusion
• A smooth, red tongue

Symptoms in children

• Slow growth and development
• Weakness and tiredness
• Irritability or being very fussy
• Trouble feeding or poor appetite

Symptoms in older adults

• Confusion and memory loss that may look like dementia
• Depression or mood changes
• Weakness and falls
• Numbness or tingling in the limbs

Causes

Main causes

• Not eating enough vitamin B12, especially if you are vegan or vegetarian
• A condition called pernicious anaemia, where the immune system attacks stomach cells that help absorb B12
• Stomach or bowel surgery that removes parts that absorb B12
• Diseases of the gut, such as Crohn’s disease or coeliac disease
• Some medicines used for heartburn or diabetes that can reduce B12 absorption

Risk factors

• Following a vegan or vegetarian diet without taking B12 supplements
• Being over 60 years old
• Having a digestive disorder like Crohn’s, coeliac disease, or atrophic gastritis
• Taking certain medicines long‑term (for example, for heartburn or diabetes)
• Having had stomach weight‑loss surgery or removal of part of the stomach or intestine

When to see a doctor

See a doctor urgently if:

• If you have sudden confusion or trouble walking
• If you feel short of breath or have chest pain
• If you lose strength in an arm or leg without explanation

Book a routine appointment if:

• If you feel very tired, weak, or have skin paleness for no clear reason
• If you have pins and needles or numbness that started recently
• If you are at risk (vegan diet, age over 60, stomach conditions) and want a blood test
• If you have memory problems or depression that isn’t getting better

Diagnosis

Your doctor will talk about your symptoms and diet, and then take a blood sample to check your vitamin B12 level. They may also check for other markers to confirm the cause.

Tests that may be done

• Blood test for vitamin B12 level
• Complete blood count to check for anaemia
• Methylmalonic acid (MMA) test – a more sensitive marker for B12 deficiency
• Homocysteine test – another marker that can be high when B12 is low

What to expect at your appointment

The doctor will likely ask about your eating habits, medicines, and any stomach or bowel conditions. A blood sample is taken from your arm, and results usually come back within a few days. Sometimes a physical exam is done to check nerve function.

Treatment

Treatment depends on the cause and severity of the deficiency. It usually involves replacing the missing vitamin B12. This can be done with high‑dose tablets or with injections. For some people, treatment needs to continue for life.

Self-care at home

• Eat foods rich in B12 – meat, fish, eggs, dairy, and fortified products like breakfast cereals
• If you are vegan or vegetarian, consider taking a B12 supplement after talking to your doctor
• Limit alcohol, as it can affect B12 absorption
• Do not stop any prescribed treatment without consulting your doctor

Medical treatments

Treatment is tailored to each person. It may include B12 injections given into a muscle (often for pernicious anaemia or severe deficiency), or high‑dose B12 tablets taken by mouth. Some people may be advised to use a nasal spray or gel. Your doctor will decide the best option based on the cause of your deficiency. All treatments aim to bring your B12 level back to normal and relieve symptoms.

When is surgery considered?

Surgery is not used to treat vitamin B12 deficiency itself. However, if the deficiency is caused by a condition that requires surgery (such as Crohn’s disease or a stomach tumour), that will be managed separately.

Living with this condition

If you need ongoing treatment, it helps to keep a regular schedule for injections or tablets. Watch for symptoms like tiredness or pins and needles, and let your doctor know if they return. With proper treatment, most people feel much better.

Lifestyle tips

• Follow your treatment plan exactly as prescribed
• Eat a balanced diet that includes B12, or use fortified foods
• Stay active – gentle exercise like walking can boost your energy
• Manage stress with relaxation techniques, hobbies, or talking to friends

Diet and exercise

Eat foods that are naturally high in B12 (meat, fish, eggs, milk, yoghurt, cheese) or choose fortified versions (plant milks, breakfast cereals). If you are vegan, a B12 supplement is very important. Regular physical activity, even light exercise, can help with energy and mood.

Mental health and emotional wellbeing

Low B12 can cause depression, anxiety, or memory problems. Many people notice their mood improves once B12 levels are corrected. If you feel very down or worried, talk to your doctor – they can support you and may suggest mental health resources.

Prevention

In many cases, yes. Eating enough B12‑rich foods or taking a supplement can prevent deficiency, especially if you are at risk. Check with your doctor to know what is right for you.

Screening programmes

If you are at risk – for example, if you are vegan, over 60, or have a stomach condition – ask your doctor about periodic blood tests to check your B12 level. Early detection can prevent symptoms and complications.

Complications

If left untreated

• Permanent nerve damage leading to numbness, weakness, or trouble walking
• Severe anaemia causing extreme tiredness and heart strain
• Memory loss or problems thinking clearly that may not fully reverse
• Increased risk of heart problems because of high homocysteine levels

Long-term outlook

The outlook is very good if treatment is started early. Most people recover completely or improve a great deal. Even people with long‑standing deficiency often feel much better once their B12 level is corrected, though some nerve problems may take time or not fully reverse. With follow‑up care, you can manage the condition and live a full, healthy life.

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