vitamin B12 deficiency

Vitamin B12 deficiency occurs when your body does not have enough vitamin B12 to support essential functions such as red blood cell production, normal nerve function, and DNA formation. It can develop because you do not consume enough vitamin B12, your body cannot absorb it properly, or both.

Early signs may be subtle. You might feel unusually tired, weak, or lightheaded. As the deficiency progresses, symptoms can include numbness, tingling in the hands or feet, balance problems, or changes in memory and concentration. Importantly, neurological problems can occur even without anemia.

Vitamin B12 is naturally present in foods such as fish, shellfish, meat, eggs, and dairy products. Fortified cereals, nutritional yeast products, and some plant-based milk alternatives can also provide it. However, changing your diet may not be enough if an underlying medical condition prevents proper absorption.

This guide explains the common signs of vitamin B12 deficiency, what causes it, which foods can help you get enough vitamin B12, and when to seek medical advice.

Key Takeaways

Vitamin B12 deficiency can affect red blood cells, the nervous system, and normal cellular functions.
Common symptoms include fatigue, weakness, pale skin, a sore tongue, numbness, tingling, and balance difficulties.
Causes include low dietary intake, impaired absorption, pernicious anemia, certain digestive conditions, and some medications.
Fish, shellfish, meat, eggs, dairy products, and appropriately fortified foods are reliable dietary sources.
People following vegan diets and those with absorption problems may need supplements or medical treatment.
A blood test and clinical assessment can help identify a deficiency.
Early diagnosis matters because prolonged vitamin B12 deficiency can cause neurological damage that may not fully reverse.

What Is Vitamin B12 Deficiency?

Vitamin B12, also called cobalamin, is a water-soluble vitamin that your body needs for several important processes.

It helps your body:

Produce healthy red blood cells.
Maintain normal nerve function.
Make DNA, the genetic material in cells.
Support normal metabolism and cellular activity.

Your body cannot make enough vitamin B12 on its own, so you need to obtain it from your diet or suitable supplements.

When your vitamin B12 level becomes too low, your body may struggle to produce healthy blood cells and maintain normal neurological function. One possible consequence is megaloblastic anemia, a condition in which red blood cells become unusually large and do not develop normally.

Vitamin B12 deficiency can also affect the nervous system without causing anemia. That is one reason symptoms such as tingling, numbness, or balance problems should not be ignored. <Cite refs={[“turn315549search1″,”turn315549search0”]}/>

What Are the Signs and Symptoms of Vitamin B12 Deficiency?

Vitamin B12 deficiency symptoms vary from person to person. Some people develop noticeable problems, while others may have few symptoms initially.

Because the body stores vitamin B12, symptoms can take years to appear after intake or absorption becomes inadequate.

1. Persistent fatigue and weakness

Unusual tiredness is one of the common signs of vitamin B12 deficiency.

When deficiency affects red blood cell production, your body may have difficulty delivering enough oxygen to its tissues. You might feel exhausted, weak, or less able to complete your usual activities.

However, fatigue has many possible causes, including poor sleep, iron deficiency, thyroid disorders, and other medical conditions. It should not automatically be attributed to low vitamin B12.

2. Pale skin or changes in complexion

Some people with vitamin B12 deficiency develop pale skin because of anemia.

In certain cases, the skin may also appear slightly yellowish. This can occur when abnormal red blood cells break down more rapidly than usual.

Skin color changes alone cannot confirm a vitamin deficiency. If you notice persistent pallor or yellowing, arrange a medical assessment.

3. Numbness or tingling in the hands and feet

Vitamin B12 is essential for normal nerve function. A deficiency can damage nerves and cause sensations such as:

Pins and needles
Tingling in the fingers or toes
Reduced sensation
Burning or unusual nerve sensations
Numbness in the hands or feet

These symptoms deserve particular attention because neurological problems can develop even when a person does not have anemia.

4. Balance problems or difficulty walking

As deficiency-related nerve problems progress, some people develop unsteadiness, reduced coordination, or difficulty walking.

These changes may increase the risk of falls, especially in older adults. New or worsening balance problems should be evaluated promptly rather than treated only with dietary changes.

5. A sore, red, or smooth tongue

Vitamin B12 deficiency can cause glossitis, which is inflammation of the tongue.

The tongue may look unusually smooth, red, or swollen. Some people also experience soreness in the mouth or discomfort when eating.

These symptoms can occur for other reasons, so medical assessment is useful if they persist.

6. Memory or concentration changes

Vitamin B12 supports normal nervous system function. Deficiency may be associated with confusion, slower thinking, difficulty concentrating, or memory changes.

These symptoms are not specific to vitamin B12 deficiency, and supplements are not a proven way to prevent or treat memory problems in people whose B12 status is already adequate.

If you notice significant or progressive changes in thinking or memory, seek medical advice.

7. Shortness of breath, dizziness, or a racing heartbeat

When vitamin B12 deficiency causes anemia, you may experience:

Breathlessness during activity
Dizziness or lightheadedness
Headaches
Heart palpitations
Reduced exercise tolerance

These symptoms can indicate anemia or another health issue. Severe breathlessness, chest pain, fainting, or a very rapid heartbeat requires urgent medical assessment.

8. Digestive symptoms and appetite changes

Some people experience a reduced appetite, unexplained weight loss, diarrhea, constipation, or other digestive symptoms.

These symptoms are nonspecific. If digestive problems persist, a healthcare professional can investigate possible causes rather than assuming vitamin B12 deficiency is responsible.

Important: This list is not a diagnostic checklist. A healthcare professional can assess your symptoms and decide whether blood tests or further investigations are needed. <Cite refs={[“turn315549search0″,”turn315549search1″,”turn315549search2”]}/>

Vitamin B12 deficiency awareness with a person experiencing tiredness and foods that provide vitamin B12.

What Causes Vitamin B12 Deficiency?

There are two major reasons vitamin B12 deficiency develops: inadequate intake and poor absorption.

Some people do not consume enough vitamin B12, while others eat B12-containing foods but cannot absorb sufficient amounts. Understanding the underlying cause is important because treatment depends on why the deficiency occurred.

1. Not eating enough vitamin B12-rich foods

Vitamin B12 occurs naturally in animal-derived foods. People who avoid these foods and do not use reliable fortified products may not get enough.

Dietary risk may be higher for people who:

Follow a vegan diet without fortified foods or supplements.
Eat very few animal products.
Have a highly restricted diet.
Have difficulty obtaining or preparing varied meals.

A vegetarian diet does not automatically cause vitamin B12 deficiency. People who regularly consume sufficient dairy products, eggs, or suitable fortified foods may meet their needs.

2. Pernicious anemia

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

Normally, a stomach protein called intrinsic factor helps vitamin B12 get absorbed in the small intestine. In pernicious anemia, the body cannot produce enough functional intrinsic factor because of damage to the cells involved in its production or related autoimmune processes.

As a result, simply eating more vitamin B12-rich foods may not solve the problem. Medical treatment is often necessary.

3. Digestive conditions that affect absorption

Several gastrointestinal conditions can interfere with vitamin B12 absorption, including:

Crohn’s disease
Celiac disease
Certain disorders affecting the stomach lining
Some conditions affecting the pancreas
Disorders involving the small intestine

The effect depends on the condition and its severity. If you have a digestive disorder and develop possible deficiency symptoms, ask your healthcare professional whether testing is appropriate.

4. Stomach or intestinal surgery

Some procedures can reduce the body’s ability to absorb vitamin B12.

Examples include certain weight-loss surgeries and operations that remove parts of the stomach or small intestine involved in absorption.

People who have had these procedures may need ongoing monitoring and, in some cases, long-term supplementation.

5. Certain medications

Some medicines can affect vitamin B12 absorption over time.

Examples include:

Metformin, commonly used to treat type 2 diabetes.
Proton pump inhibitors, such as omeprazole, which reduce stomach acid.
H2-receptor blockers, another type of acid-reducing medication.

Taking these medicines does not mean you will definitely develop a deficiency. Do not stop prescribed medication on your own. Discuss your risk and whether monitoring is appropriate with your healthcare professional.

6. Older age

Some older adults produce less stomach acid, which can make it harder to release vitamin B12 from food proteins. This may reduce absorption of naturally occurring B12 from foods.

However, vitamin B12 deficiency is not an inevitable part of aging. Fortified foods, supplements, and appropriate medical treatment can help address individual needs.

7. Nitrous oxide exposure

Nitrous oxide, sometimes called laughing gas, can inactivate vitamin B12 and interfere with its normal function in the body.

Repeated or heavy exposure can cause neurological problems, particularly in people who already have low B12 stores. If you have used nitrous oxide and develop numbness, weakness, or difficulty walking, seek urgent medical advice.

These causes are well documented in clinical guidance from the NIH and MedlinePlus. <Cite refs={[“turn315549search1″,”turn315549search2″,”turn315549search0”]}/>

Who Is at Higher Risk of Vitamin B12 Deficiency?

You may be more likely to develop vitamin B12 deficiency if you:

Follow a vegan diet without a dependable source of vitamin B12.
Are an older adult with reduced absorption from food.
Have pernicious anemia.
Have celiac disease, Crohn’s disease, or another condition affecting absorption.
Have undergone certain stomach or intestinal operations.
Use metformin or long-term acid-reducing medication.
Have a persistently limited diet or difficulty accessing varied foods.
Have a medical history that affects nutrient absorption.

Pregnant and breastfeeding people who follow restrictive diets should pay particular attention to vitamin B12 intake because adequate status is important for both parent and infant.

Having one risk factor does not prove that you have a deficiency. It means you may benefit from discussing your intake, symptoms, and testing needs with a healthcare professional.

Which Foods Help Prevent Vitamin B12 Deficiency?

A varied diet that includes dependable vitamin B12 sources can help prevent deficiency caused by low intake.

The following foods provide naturally occurring or added vitamin B12.

Animal-based foods

Shellfish: Clams and oysters can contain very high amounts of vitamin B12.

Fish: Salmon, trout, sardines, and tuna can contribute meaningful amounts.

Meat: Beef and other meats are useful sources.

Eggs: Eggs provide vitamin B12, although the amount in one egg is relatively modest.

Dairy products: Milk, yogurt, and cheese can contribute to daily intake.

Fortified foods

Some foods contain vitamin B12 added during manufacturing, including:

Fortified breakfast cereals
Fortified plant-based milk alternatives
Fortified nutritional yeast products
Selected fortified meat alternatives

Not every product in these categories contains vitamin B12. Check the nutrition label to confirm the amount per serving.

Unfortified fruits, vegetables, grains, nuts, beans, and seeds are not reliable sources of vitamin B12. Certain fermented foods or algae products are sometimes promoted as B12 sources, but they should not be relied on to prevent deficiency unless their bioavailable B12 content is established and dependable. <Cite refs={[“turn315549search3″,”turn315549search6”]}/>

Vitamin B12-rich foods including salmon, shellfish, beef, eggs, dairy products, and fortified foods.

Vitamin B12 Food Sources: A Quick Reference Chart

The table below provides approximate amounts for selected foods using reference values from the NIH Office of Dietary Supplements. Actual values vary by serving size, preparation, species, and brand.

Food	Example serving	Approximate vitamin B12
Beef liver, cooked	3 oz	70.7 mcg
Clams, cooked	3 oz	17 mcg
Oysters, cooked	3 oz	14.9 mcg
Salmon, cooked	3 oz	2.6 mcg
Canned light tuna	3 oz	2.5 mcg
Ground beef, cooked	3 oz	2.4 mcg
Cow’s milk	1 cup	1.3 mcg
Plain yogurt	6 oz	1.0 mcg
Fortified breakfast cereal	1 serving	Varies by brand
Fortified plant-based milk	1 cup	Varies by brand
Large egg	1 egg	0.5 mcg
Cheddar cheese	1½ oz	0.5 mcg

Values are approximate examples, not guarantees for every product. Fortified foods vary substantially, so check the label.

How to use this food chart

If you eat animal products, you can combine several sources throughout the day. For example, milk at breakfast, a suitable fish meal at lunch or dinner, and yogurt or eggs as part of another meal can contribute to your overall intake.

If you follow a vegan diet, choose products specifically fortified with vitamin B12 or discuss a suitable supplement with a healthcare professional. Do not assume a plant-based product contains B12 just because it is marketed as healthy.

Best Sources of Vitamin B12: Natural and Fortified Options

How Is Vitamin B12 Deficiency Diagnosed?

Symptoms alone cannot establish whether you have vitamin B12 deficiency. A healthcare professional will consider your symptoms, diet, medical history, medications, and possible absorption problems.

1. Blood tests

A clinician may order a blood test to measure your vitamin B12 level. A complete blood count may also be used to look for anemia or changes in red blood cells.

A low vitamin B12 result can support the diagnosis, but results sometimes need further interpretation.

2. Additional tests when needed

If the result is borderline or does not match the symptoms, your healthcare professional may consider additional tests, such as methylmalonic acid (MMA), which can help assess whether vitamin B12 is functionally insufficient.

Depending on the suspected cause, further investigations may include tests for pernicious anemia or conditions that interfere with absorption.

3. Review of symptoms and risk factors

Tell your healthcare professional if you:

Follow a vegan or highly restricted diet.
Have persistent tingling or numbness.
Have digestive conditions or a history of gastrointestinal surgery.
Take metformin or long-term acid-reducing medication.
Have a family or personal history of relevant autoimmune conditions.

Do not delay medical assessment if you have progressive neurological symptoms. A deficiency can affect the nervous system even when anemia is absent. <Cite refs={[“turn315549search1″,”turn315549search2”]}/>

Vitamin B12 Health Professional Fact Sheet

How Is Vitamin B12 Deficiency Treated?

Treatment depends on the severity of the deficiency and the underlying cause.

Dietary changes

If low intake is the main reason, a healthcare professional or registered dietitian may recommend increasing reliable vitamin B12 sources or adding fortified foods.

For people who follow vegan diets, a dependable supplement plan may be needed because unfortified plant foods are not reliable sources.

Oral vitamin B12 supplements

Oral supplements may be suitable for many people. The required dose depends on the individual’s situation, including whether the deficiency is due to low intake or an absorption problem.

Some treatment regimens use doses much higher than the routine daily requirement because only a portion of a large oral dose is absorbed.

Vitamin B12 injections

Injections may be recommended for some people, particularly when deficiency is severe, neurological symptoms are present, or absorption is significantly impaired.

Some underlying conditions require ongoing or lifelong treatment. Your healthcare professional can determine which option is appropriate.

Treating the underlying cause

If a medication, digestive condition, or autoimmune disorder contributes to deficiency, the treatment plan may also need to address that issue.

Do not begin high-dose treatment or stop prescribed medication without appropriate guidance. Early diagnosis and treatment can improve outcomes, although some long-standing nerve damage may not fully reverse. <Cite refs={[“turn315549search0″,”turn315549search2”]}/>

Balanced meal with salmon, egg, dairy, whole grains, and vegetables alongside foods that provide vitamin B12.

Can Vitamin B12 Deficiency Be Prevented?

In many cases, deficiency caused by low dietary intake can be prevented by including reliable vitamin B12 sources in your eating pattern.

Try these practical steps:

Include vitamin B12-rich foods. Choose suitable fish, meat, eggs, dairy products, or fortified alternatives.
Check fortified-food labels. Confirm that vitamin B12 is listed and check the amount per serving.
Plan a vegan diet carefully. Use reliable fortified products or an appropriate supplement plan rather than relying on unfortified plant foods.
Discuss risk factors with a clinician. Digestive conditions, surgery, certain medicines, and pernicious anemia may require monitoring or treatment.
Do not ignore persistent symptoms. Fatigue, tingling, weakness, and balance problems deserve assessment if they are unexplained or ongoing.
Follow through with treatment. If you have been diagnosed with deficiency, follow your prescribed plan and any recommended monitoring.

A healthy diet is valuable, but it cannot prevent every case of vitamin B12 deficiency. People with absorption problems may need medical treatment even when their diet contains enough vitamin B12.

Frequently Asked Questions

What are the first signs of vitamin B12 deficiency?

Early signs may include fatigue, weakness, pale skin, a sore tongue, or reduced appetite. Some people develop tingling or numbness in their hands and feet. Symptoms vary, and a blood test may be needed to confirm deficiency.

What is the most common cause of vitamin B12 deficiency?

There is no single cause for everyone. Low dietary intake, impaired absorption, pernicious anemia, digestive conditions, certain medications, and gastrointestinal surgery can all contribute.

Can vitamin B12 deficiency cause tingling in the hands and feet?

Yes. Vitamin B12 is important for normal nerve function, and deficiency can cause tingling, numbness, or other neurological symptoms. Seek medical advice if these symptoms develop, particularly if they worsen or affect walking.

Which foods are best for vitamin B12 deficiency?

Clams, beef liver, fish, meat, eggs, milk, and yogurt are useful sources. Fortified cereals, plant-based milk alternatives, and fortified nutritional yeast can also contribute. If you have a diagnosed deficiency, food changes alone may not be enough.

Can vegetarians or vegans develop vitamin B12 deficiency?

Yes, especially if they do not consume reliable fortified products or supplements. Dairy products and eggs can provide B12 for some vegetarians, while vegans generally need fortified foods or a suitable supplement plan.

How long does it take to recover from vitamin B12 deficiency?

Recovery depends on the cause, severity, and treatment. Blood-related symptoms may begin improving over weeks, while neurological symptoms can take longer and may not fully resolve if nerve damage has been prolonged. Your healthcare professional can monitor your progress.

Is vitamin B12 deficiency serious?

It can be. Untreated deficiency may cause anemia and neurological complications, some of which can become permanent. Early assessment and treatment are important.

Can I treat vitamin B12 deficiency with food alone?

Sometimes dietary changes help when low intake is the cause. However, people with pernicious anemia, significant absorption problems, or severe deficiency may need supplements or injections. Treatment should be based on the underlying cause.

Conclusion: Recognize Vitamin B12 Deficiency Early

Vitamin B12 deficiency can affect your energy, red blood cell production, and nervous system. Persistent fatigue, pale skin, a sore tongue, numbness, tingling, balance problems, and cognitive changes are possible warning signs, although none of these symptoms proves that you have a deficiency.

Reliable food sources include fish, shellfish, meat, eggs, dairy products, and appropriately fortified foods. People who follow vegan diets or have conditions that affect absorption may need additional planning, testing, or supplementation.

The most important step is to identify the cause rather than relying on symptoms or diet changes alone. If you have ongoing symptoms or risk factors, seek medical advice and ask whether vitamin B12 testing is appropriate. Early treatment can help prevent complications and protect long-term nerve health.