Vitamin B12 Deficiency: Symptoms, Causes, Foods & When You Need a Test

Feeling tired all the time? Experiencing tingling in your hands or feet? Having trouble concentrating?

These symptoms can have many different causes, but one nutrient that should not be overlooked is vitamin B12.

Vitamin B12 is essential for healthy red blood cells, nerves and DNA production. A deficiency can develop slowly, and some people may not notice symptoms until the deficiency becomes significant.

It is also particularly relevant for people who eat little or no animal-source food, as well as people who have conditions or take medicines that can interfere with B12 absorption.

So, what are the symptoms of vitamin B12 deficiency? What foods contain B12? Who is at risk? And when should you get a vitamin B12 test?

Let's take a closer look.

🔎 What Is Vitamin B12?

Vitamin B12, also called cobalamin, is a water-soluble vitamin that plays several important roles in the body.

It helps:

🩸 Produce healthy red blood cells
🧠 Maintain normal nerve function
🧬 Make DNA
⚡ Support normal energy metabolism
❤️ Maintain normal neurological function

Adults generally need around 2.4 micrograms (mcg) of vitamin B12 per day, although requirements are higher during pregnancy and breastfeeding.

The body can store a substantial amount of B12, which is why deficiency may take a long time to become noticeable.

⚠️ Vitamin B12 Deficiency Symptoms

Vitamin B12 deficiency can affect different parts of the body, and symptoms vary from person to person.

Common symptoms can include:

😴 Persistent tiredness or weakness
🩸 Pale skin
🧠 Difficulty concentrating or memory problems
🦶 Tingling or numbness in the hands and feet
⚖️ Balance or walking problems
👅 Sore or inflamed tongue
❤️ Heart palpitations
🍽️ Reduced appetite or unexplained weight loss
😟 Changes in mood
🧠 Confusion in more severe cases

One important point: these symptoms do not automatically mean you have B12 deficiency.

Fatigue, brain fog, numbness and many other symptoms can occur with numerous health conditions. NICE specifically notes that symptoms of B12 deficiency are often not exclusive to the condition.

🥗 Who Is More Likely to Develop Vitamin B12 Deficiency?

Some people have a higher risk than others.

🌱 People Following Vegetarian or Vegan Diets

Natural vitamin B12 is mainly found in animal-derived foods.

People who eat little or no meat, fish, eggs or dairy may therefore have difficulty getting enough B12 unless they regularly consume fortified foods or appropriate supplements.

This is particularly relevant in India, where vegetarian diets are common. Studies in Indian populations have reported substantial rates of low B12 status, although prevalence varies considerably depending on the population and definition used.

👴 Older Adults

As people age, changes in the stomach and digestive system can reduce the absorption of B12 from food.

💊 People Taking Certain Medicines

Long-term use of some medicines can be associated with lower B12 levels.

These include:

Metformin
Proton pump inhibitors (PPIs)
Certain other medicines that affect stomach acid or nutrient absorption

This does not mean you should stop prescribed medication. If you take these medicines regularly, discuss B12 testing with your healthcare professional if appropriate. NICE specifically lists metformin and proton pump inhibitors among risk factors.

🏥 People With Digestive Problems

Conditions affecting the stomach or small intestine can interfere with B12 absorption.

Examples include:

Celiac disease
Some gastrointestinal disorders
Autoimmune gastritis
Previous stomach or intestinal surgery

🍳 Which Foods Are High in Vitamin B12?

Vitamin B12 occurs naturally mainly in animal foods.

Good dietary sources include:

Food	Vitamin B12 Source
🐟 Fish	Naturally rich source
🥩 Meat	Naturally rich source
🍗 Chicken and poultry	Source of B12
🥚 Eggs	Provides B12
🥛 Milk	Provides B12
🧀 Dairy products	Provides B12
🥣 Fortified breakfast cereals	B12 may be added
🌱 Fortified nutritional yeast	Some products contain added B12

Not every product in these categories contains the same amount of B12.

Always check the nutrition label, particularly for fortified foods.

Plant foods do not naturally provide reliable amounts of vitamin B12 unless they have been fortified.

🌱 Can Vegetarians Get Enough Vitamin B12?

Yes, but it requires some planning.

Vegetarians who consume milk, dairy products and eggs may obtain B12 from these foods, but intake can still be insufficient depending on the overall diet.

For vegans, reliable sources generally need to come from fortified foods or vitamin B12 supplements.

This is one reason why simply eating a "healthy vegetarian diet" does not automatically guarantee adequate B12.

If you follow a vegetarian or vegan diet for a long period, discussing your B12 intake and whether testing or supplementation is appropriate can be worthwhile.

🧪 How Is Vitamin B12 Deficiency Diagnosed?

The most common starting point is a blood test for vitamin B12.

Depending on the situation, a healthcare professional may consider:

Total vitamin B12
Active B12 (holotranscobalamin)
Methylmalonic acid (MMA)
Homocysteine
Complete blood count and other tests to investigate anemia or alternative causes

NICE recommends total B12 or active B12 as initial diagnostic tests in most people with suspected deficiency, while additional testing may be useful when results are unclear.

A single number should not always be interpreted in isolation. Laboratory reference ranges differ, and symptoms, diet, medications and medical history can all matter.

⚠️ Important

Do not start high-dose B12 treatment simply because you feel tired.

If you suspect a deficiency, getting appropriate medical evaluation is a better approach.

💊 Do You Need Vitamin B12 Supplements?

Not everyone needs a B12 supplement.

Supplementation may be appropriate when:

Your diet provides very little B12
A blood test shows deficiency
You have a condition affecting B12 absorption
A healthcare professional recommends supplementation
You take certain medicines associated with B12 deficiency and your clinician recommends monitoring or supplementation

Treatment depends on why the deficiency occurred.

For dietary deficiency, oral B12 may be sufficient in many cases. When absorption is severely impaired, injections may be recommended.

NICE notes that treatment can involve oral replacement or intramuscular injections depending on the cause and individual circumstances. Some causes, such as autoimmune gastritis or certain major gastrointestinal surgeries, may require lifelong replacement.

🧠 Can Vitamin B12 Deficiency Affect the Nervous System?

Yes.

One of the reasons B12 deficiency deserves attention is its effect on the nervous system.

Deficiency can cause:

Tingling
Numbness
Balance problems
Difficulty walking
Memory or concentration problems

Neurological symptoms can sometimes occur even without anemia.

The NIH notes that neurological damage can occur with B12 deficiency and that early treatment is important.

This is one reason persistent unexplained numbness or tingling should not simply be dismissed as a vitamin deficiency—or assumed to be one. It deserves proper medical evaluation.

⚠️ B12 Deficiency vs Low B12 Intake: What's the Difference?

These terms are sometimes used interchangeably, but they aren't exactly the same.

Low dietary intake means you aren't consuming enough B12.

Vitamin B12 deficiency means your body's B12 status is inadequate.

A person can consume B12 but still become deficient if their body cannot absorb it properly.

For example, problems involving intrinsic factor, certain gastrointestinal conditions or some surgeries can interfere with absorption.

This is why simply eating more B12-rich food may not solve every case.

🥛 Is Milk Enough for Vitamin B12?

Milk contains vitamin B12, but whether it provides enough for an individual depends on the total diet and how much is consumed.

The same applies to eggs and other B12-containing foods.

Rather than relying on one food, focus on your overall dietary pattern and consider fortified foods or supplements when appropriate.

🚨 What Happens If B12 Deficiency Is Ignored?

Untreated vitamin B12 deficiency can lead to anemia and neurological problems.

Some neurological effects can become serious, and treatment may not immediately reverse every symptom.

The good news is that vitamin B12 deficiency is generally treatable, and identifying the underlying cause is an important part of management.

📊 Quick Guide: Are You at Higher Risk?

Situation	Possible B12 Risk
🌱 Vegan diet	Higher
🥗 Vegetarian diet	May be higher
👴 Older age	Higher
💊 Long-term metformin use	Higher
💊 Long-term PPI use	Higher
🏥 Gastrointestinal disease	Higher
🏥 Certain stomach/intestinal surgeries	Higher
🥩 Regular B12-rich food intake	Generally lower dietary risk

Having a risk factor doesn't mean you are deficient. It simply means B12 status may deserve more attention.

✅ Key Takeaway

Vitamin B12 is a small nutrient with a big role in your body.

🩸 It helps make healthy red blood cells
🧠 It supports normal nerve function
🧬 It is needed for DNA production
🥩 It is naturally found mainly in animal-source foods
🌱 Vegetarians and vegans need reliable B12 sources
💊 Some medicines and digestive conditions can affect B12 status
🧪 A blood test can help identify deficiency
👨‍⚕️ Treatment depends on the cause

👉 If you have persistent fatigue, unexplained numbness or tingling, balance problems, or other symptoms—especially if you have risk factors for B12 deficiency—talk to a healthcare professional rather than self-diagnosing.

Disclaimer

This article is for general educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Vitamin B12 requirements and treatment vary between individuals. If you have symptoms, risk factors, abnormal blood-test results, or concerns about vitamin B12 deficiency, consult a qualified healthcare professional.