KandyWandy: Vitamin B12 Deficiency: 12 Signs and Symptoms, Causes, Testing and Treatment

Vitamin B12 Deficiency: 12 Signs and Symptoms, Causes, Testing and Treatment

Vitamin B12 is an essential nutrient your body needs to make healthy red blood cells, support the nervous system and produce DNA.

When your body does not get or absorb enough vitamin B12, deficiency can develop. The symptoms may begin gradually and can sometimes be mistaken for stress, ageing or other health problems.

Possible symptoms include extreme tiredness, weakness, numbness or tingling, balance problems, a sore tongue, memory difficulties and changes in mood.

Importantly, vitamin B12 deficiency can affect the nervous system even when obvious anaemia is not present. If deficiency continues untreated, some neurological problems can become difficult to reverse.

Fortunately, vitamin B12 deficiency can usually be identified with appropriate medical assessment and treated once the cause is understood.

Here are 12 possible signs and symptoms, who is most at risk and what you should do if you think your vitamin B12 may be low.

What Is Vitamin B12 Deficiency?

Vitamin B12, also known as cobalamin, is a water-soluble vitamin.

Your body needs it for several important functions, including:

Producing healthy red blood cells
Maintaining normal nerve function
Making DNA
Supporting normal cell metabolism

Unlike many nutrients, vitamin B12 is naturally found mainly in animal-derived foods. Some plant-based foods are fortified with B12.

Your body also stores vitamin B12, particularly in the liver. Because these stores can last for a considerable period, deficiency may take time to develop.

A person can become deficient because they do not consume enough B12, but problems absorbing the vitamin are another important cause.

12 Possible Signs and Symptoms of Vitamin B12 Deficiency

Symptoms vary considerably between individuals.

Some people develop anaemia, neurological symptoms or both. Others may initially experience only vague symptoms such as tiredness.

1. Extreme Tiredness

Persistent fatigue is one of the symptoms associated with vitamin B12 deficiency.

B12 is required for normal red blood cell production. When deficiency contributes to anaemia, the body's tissues may receive less oxygen than they need, which can leave you feeling unusually tired or weak.

However, fatigue has many possible causes.

Poor sleep, iron deficiency, thyroid disorders, infections, depression and numerous medical conditions can produce similar symptoms.

Therefore, tiredness alone cannot diagnose B12 deficiency.

2. Weakness

Some people with vitamin B12 deficiency experience general weakness or reduced energy.

Everyday activities may begin to feel more difficult than usual.

Persistent or worsening weakness deserves medical attention because vitamin deficiencies are only one of many possible explanations.

3. Numbness or Tingling

Vitamin B12 is important for maintaining healthy nerves.

Deficiency can cause neurological symptoms such as numbness, pins and needles or tingling, particularly in the hands, legs or feet.

These symptoms should not automatically be blamed on B12 deficiency because diabetes, trapped nerves and other neurological conditions can produce similar problems.

Persistent numbness or tingling should be professionally assessed.

4. Problems With Balance or Walking

Significant vitamin B12 deficiency can affect the nervous system and potentially interfere with balance, coordination and walking.

Someone may feel unsteady or notice that their movements are less coordinated.

New or worsening problems with walking or balance warrant medical evaluation rather than self-treatment with supplements.

5. Pale Skin

Anaemia associated with vitamin B12 deficiency can sometimes make the skin appear paler than usual.

Skin colour varies considerably between people, so paleness may be more noticeable in areas such as the inside of the lower eyelid, palms or nail beds.

Pale skin alone does not establish the cause of anaemia.

6. Shortness of Breath

Anaemia can sometimes cause breathlessness, particularly during physical activity.

However, unexplained shortness of breath can also be associated with heart, lung and other potentially serious medical conditions.

New, severe or unexplained breathing difficulty requires appropriate medical assessment.

7. A Sore or Red Tongue

Vitamin B12 deficiency can sometimes cause changes to the tongue.

The tongue may become sore, smooth, swollen or unusually red. This is sometimes called glossitis.

Mouth ulcers can also occur in some people.

Many other conditions can cause mouth or tongue problems, so persistent changes should be assessed.

8. Memory or Concentration Problems

Because vitamin B12 is important for neurological function, deficiency can sometimes affect thinking and concentration.

Possible symptoms may include:

Difficulty concentrating
Forgetfulness
Confusion
Problems thinking clearly

These symptoms have numerous possible causes, particularly in older adults.

Vitamin B12 deficiency should therefore be considered as one possibility rather than assuming that memory problems are simply caused by ageing.

9. Mood Changes

Some people with vitamin B12 deficiency experience psychological or mood-related symptoms.

These can include irritability, low mood or other changes in mental wellbeing.

Depression and other mental health conditions are complex and should not automatically be attributed to a vitamin deficiency.

Anyone experiencing persistent or severe changes in mood should seek appropriate professional support.

10. Vision Problems

Severe vitamin B12 deficiency can, in uncommon circumstances, affect the optic nerve and cause visual problems.

Any new or unexplained change in vision deserves medical assessment.

Do not attempt to treat vision changes yourself by simply taking vitamin supplements.

11. Heart Palpitations

Anaemia can sometimes make the heart beat faster as the body attempts to deliver sufficient oxygen to its tissues.

Some people may therefore notice a rapid or unusually noticeable heartbeat.

Palpitations have many potential causes.

Seek urgent medical attention if palpitations occur with severe chest pain, fainting, significant breathlessness or other concerning symptoms.

12. Loss of Appetite or Unexplained Weight Loss

Vitamin B12 deficiency can sometimes be associated with reduced appetite and weight loss.

Unintentional weight loss should not automatically be attributed to vitamin deficiency because many medical conditions can cause it.

If you are losing weight without trying, discuss this with a healthcare professional.

Can You Have Vitamin B12 Deficiency Without Anaemia?

Yes.

This is an important point.

Vitamin B12 deficiency can cause neurological symptoms even without obvious anaemia.

For example, a person may experience numbness, tingling, balance problems or cognitive changes even when anaemia is not the main presenting problem.

This is one reason persistent neurological symptoms should not be ignored.

Early identification and treatment are important because prolonged neurological damage from severe B12 deficiency may not always be completely reversible.

What Causes Vitamin B12 Deficiency?

There are several possible causes.

Not Getting Enough B12 From Food

Vitamin B12 occurs naturally mainly in animal-derived foods.

People who follow vegan or highly restrictive diets can be at increased risk unless they regularly consume appropriately fortified foods or suitable supplements.

Pernicious Anaemia

Pernicious anaemia is an autoimmune condition that interferes with the body's ability to absorb vitamin B12.

Normally, a protein called intrinsic factor helps the body absorb B12 in the intestine.

When this process is disrupted, deficiency can develop even if someone's diet contains plenty of vitamin B12.

Stomach or Intestinal Conditions

Certain gastrointestinal conditions can interfere with nutrient absorption.

Examples include conditions affecting the stomach or small intestine.

Previous gastrointestinal surgery can also affect the body's ability to absorb B12.

Certain Medicines

Some medications can reduce vitamin B12 absorption when used for prolonged periods.

Examples can include the diabetes medicine metformin and certain medicines that reduce stomach acid.

This does not mean you should stop these medicines.

If you take them and are concerned about B12 deficiency, discuss the issue with the healthcare professional managing your treatment.

Who Is More Likely to Develop Vitamin B12 Deficiency?

Risk may be higher among:

Older adults
People following vegan diets without adequate fortified foods or supplementation
People following very restrictive diets
People with pernicious anaemia
People with certain gastrointestinal conditions
People who have undergone some types of stomach or intestinal surgery
People taking certain medications for prolonged periods
People with conditions that interfere with nutrient absorption

Having a risk factor does not mean you definitely have a deficiency.

It means your individual circumstances may warrant discussion with a healthcare professional.

Which Foods Contain Vitamin B12?

Natural food sources include:

Fish
Shellfish
Meat
Poultry
Eggs
Milk
Yoghurt
Cheese
Other dairy products

Some foods are fortified with vitamin B12, including certain:

Breakfast cereals
Plant-based milk alternatives
Nutritional yeast products
Meat substitutes

Fortification varies considerably between countries and brands.

Check the nutrition label rather than assuming that every plant-based product contains vitamin B12.

Can Vegans Get Enough Vitamin B12?

Yes, but it requires attention.

Because reliable natural plant sources of vitamin B12 are limited, people following vegan diets generally need dependable sources from fortified foods or supplements.

Someone eating a plant-based diet should not assume that vegetables, fruits and other whole plant foods automatically provide adequate B12.

Appropriate supplementation may be necessary.

How Is Vitamin B12 Deficiency Diagnosed?

Diagnosis generally involves considering your symptoms, medical history, diet and risk factors alongside appropriate blood tests.

Testing may include measurements related to:

Vitamin B12
Red blood cells
Haemoglobin
Folate

In some circumstances, healthcare professionals may use additional tests when the diagnosis is uncertain or when they are investigating the underlying cause.

The interpretation of B12 results is not always as simple as comparing one number with an internet reference range.

Laboratories and clinical guidelines can differ, and borderline results may require further assessment.

What Is the Treatment for Vitamin B12 Deficiency?

Treatment depends on why the deficiency developed.

Some people may be treated with oral vitamin B12 supplements.

Others may require vitamin B12 injections, particularly when absorption is significantly impaired or depending on the severity and cause of the deficiency.

Someone whose deficiency results from inadequate dietary intake may also need help ensuring their long-term diet provides reliable B12.

If an underlying condition prevents normal absorption, treatment may need to continue long term.

The appropriate treatment and dose should therefore be determined according to the individual's circumstances.

How Quickly Can You Feel Better After B12 Treatment?

Recovery varies.

Some symptoms may begin improving relatively quickly once appropriate treatment starts, while neurological symptoms can take considerably longer.

The duration and severity of the deficiency can influence recovery.

This is another reason not to leave significant neurological symptoms untreated for long periods.

Can You Take Too Much Vitamin B12?

Vitamin B12 is water-soluble, and it generally has a relatively low potential for toxicity compared with some fat-soluble vitamins.

However, that does not mean everyone needs high-dose B12 supplements.

Taking a supplement unnecessarily may also distract from finding the true cause of symptoms.

For example, persistent fatigue could result from anaemia, thyroid disease, sleep apnoea or another condition requiring different treatment.

Supplements should not replace appropriate investigation of unexplained symptoms.

Vitamin B12 vs Vitamin D Deficiency

Vitamin B12 and vitamin D are completely different nutrients, although deficiencies can sometimes produce overlapping symptoms such as fatigue or muscle-related complaints.

Vitamin B12 is particularly important for:

Red blood cell formation
DNA production
Normal nerve function

Vitamin D is particularly important for:

Calcium absorption
Bone health
Muscle function

You cannot determine which vitamin is low simply from feeling tired.

Blood testing may be appropriate when a healthcare professional suspects deficiency.

Vitamin B12 vs Iron Deficiency

Vitamin B12 deficiency and iron deficiency can both contribute to anaemia, but they have different causes and require different treatments.

Iron deficiency may occur because of:

Inadequate dietary iron
Blood loss
Pregnancy
Problems absorbing iron

Vitamin B12 deficiency can result from inadequate intake or impaired absorption.

Taking iron will not correct a vitamin B12 deficiency, and taking B12 will not correct iron deficiency.

Identifying the actual cause of anaemia is therefore important.

When Should You See a Doctor?

Speak with a healthcare professional if you experience persistent symptoms that could indicate vitamin B12 deficiency, particularly if you have known risk factors.

Seek assessment if you develop:

Persistent extreme fatigue
Unexplained weakness
Numbness or tingling
Problems with balance or walking
Persistent memory or concentration problems
A persistently sore or unusually smooth tongue
Unexplained weight loss
Symptoms of anaemia

Neurological symptoms deserve particular attention because prolonged severe B12 deficiency can potentially cause lasting nerve damage.

Seek urgent medical care for symptoms such as severe breathing difficulty, fainting, sudden neurological changes, severe chest pain or other symptoms suggesting a medical emergency.

Frequently Asked Questions

What Is Usually the First Sign of Vitamin B12 Deficiency?

There is no single first symptom.

Some people notice fatigue or weakness, while others develop neurological symptoms such as tingling or numbness. Some people initially have few noticeable symptoms.

Can Low B12 Make You Extremely Tired?

Yes, vitamin B12 deficiency can contribute to fatigue, particularly when it causes anaemia.

However, extreme tiredness has many possible causes, so testing may be necessary rather than assuming B12 is responsible.

Can Vitamin B12 Deficiency Cause Pins and Needles?

Yes.

Vitamin B12 deficiency can affect nerves and cause tingling, numbness or pins-and-needles sensations.

Persistent neurological symptoms should be medically assessed.

Can Vitamin B12 Deficiency Affect Memory?

Severe deficiency can cause neurological and cognitive symptoms, including problems with memory or concentration.

However, many other conditions can produce these symptoms.

Does B12 Give You Energy?

Vitamin B12 is necessary for normal metabolism and healthy red blood cells, but taking extra B12 does not act like a stimulant.

If you already have adequate B12 levels, taking more does not necessarily provide an energy boost.

Can Vitamin B12 Help With Weight Loss?

Vitamin B12 is not an established weight-loss treatment.

Correcting a genuine deficiency is important for health, but B12 injections or supplements should not be marketed as a shortcut for losing body fat.

Who Should Consider B12 Testing?

Testing may be appropriate for people with suggestive symptoms or important risk factors, including certain restrictive diets, gastrointestinal conditions, previous gastrointestinal surgery, pernicious anaemia or use of medications that can affect absorption.

A healthcare professional can determine whether testing is appropriate.

The Bottom Line

Vitamin B12 deficiency can affect much more than your energy levels.

Because B12 is essential for healthy red blood cells and normal nerve function, deficiency can cause symptoms ranging from fatigue and weakness to numbness, tingling, balance difficulties and cognitive changes.

Some people are at greater risk because of their diet, age, medications or problems absorbing nutrients.

The most important message is not to diagnose yourself from a symptom checklist or assume that every episode of tiredness means you need B12 supplements.

If you have persistent symptoms or significant risk factors, speak with an appropriate healthcare professional about testing.

Early diagnosis is particularly important when neurological symptoms are present because prolonged severe deficiency can potentially result in nerve damage that may not be completely reversible.

Sources and Further Reading

National Institutes of Health Office of Dietary Supplements — Vitamin B12 Fact Sheet for Health Professionals

https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

National Institutes of Health Office of Dietary Supplements — Vitamin B12 Consumer Information

https://ods.od.nih.gov/factsheets/VitaminB12-Consumer/

MedlinePlus — Vitamin B12 Deficiency Anemia

https://medlineplus.gov/ency/article/000574.htm

Cleveland Clinic — Vitamin B12 Deficiency

https://my.clevelandclinic.org/health/diseases/22831-vitamin-b12-deficiency

Medical Disclaimer

This article is for general educational and informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Speak with an appropriate healthcare professional about persistent symptoms, testing and the appropriate use of vitamin B12 supplements or injections.