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Vitamin B12-rich foods and supplements can help support adequate B12 intake when needed.
Feeling unusually tired, weak or mentally foggy? These symptoms can have many causes, but vitamin B12 deficiency is one nutritional issue worth understanding.
Vitamin B12 deficiency can affect your blood cells, nerves and overall health. Common symptoms can include tiredness, weakness, pale skin, a sore or smooth tongue, numbness or tingling, balance problems and cognitive changes.
However, these symptoms can occur for many other reasons. The only way to determine whether you have a deficiency is through appropriate medical evaluation and testing.
What Is Vitamin B12?
Vitamin B12 is an essential nutrient that your body needs for healthy red blood cell formation, DNA production and normal nervous-system function.
Unlike some nutrients that your body can make or store in different ways, vitamin B12 is obtained naturally from animal-derived foods and is also available through fortified foods and supplements.
Your body can store vitamin B12 for a long time. Because of this, deficiency may develop gradually rather than causing obvious symptoms immediately.
That can make the early signs easy to dismiss. Someone may blame tiredness on poor sleep, a busy schedule or stress without realizing that their diet or absorption may also need attention.
Why Does Your Body Need Vitamin B12?
Vitamin B12 plays several important roles in the body.
Red Blood Cells
B12 is needed for normal red blood cell formation. A deficiency can contribute to a type of anemia.
Nervous System
Vitamin B12 supports normal nervous-system function. Prolonged deficiency can cause neurological problems.
DNA Production
B12 is involved in DNA synthesis, making it important for normal cell production and maintenance.
Normal Metabolism
B12 works with other nutrients in metabolic processes that help your body use nutrients effectively.
10 Possible Signs of Vitamin B12 Deficiency
Vitamin B12 deficiency does not look exactly the same in everyone. Symptoms may develop slowly and can overlap with other health conditions.
1. Persistent Tiredness
Unusual fatigue can occur when B12 deficiency affects normal red blood cell production. But tiredness has many possible causes, including inadequate sleep, stress, anemia and other medical conditions.
2. Weakness
Some people with B12 deficiency may experience weakness or reduced physical energy. If weakness is persistent or worsening, it should be evaluated rather than automatically attributed to nutrition.
3. Pale Skin
Changes in red blood cell production can sometimes contribute to a pale appearance.
4. Numbness or Tingling
A pins-and-needles sensation, numbness or unusual sensations in the hands and feet can occur when B12 deficiency affects the nervous system.
5. Balance Problems
More significant neurological effects can interfere with balance and coordination.
6. A Sore or Smooth Tongue
Some people with B12 deficiency can develop changes in the tongue, including soreness or a smooth appearance.
7. Mouth Problems
Mouth-related symptoms can occur with nutritional deficiencies, although they are not specific to B12 deficiency.
8. Memory or Thinking Changes
B12 deficiency can affect the nervous system and may be associated with cognitive changes in some people.
9. Mood Changes
Changes in mood can occur for many reasons. Nutritional deficiency is only one possibility.
10. Shortness of Breath With Anemia
If B12 deficiency contributes to anemia, some people may experience symptoms such as shortness of breath or a faster heartbeat.
What Causes Vitamin B12 Deficiency?
B12 deficiency does not always mean someone is eating an unhealthy diet. A person can consume B12 but still have difficulty absorbing it.
1. Not Getting Enough B12 From Food
People who avoid animal-derived foods may have a higher risk of inadequate B12 intake unless they regularly consume fortified foods or appropriate supplements.
2. Problems With Absorption
Your body needs a protein called intrinsic factor to absorb vitamin B12 from food. Conditions that interfere with this process can increase the risk of deficiency.
3. Certain Stomach or Intestinal Conditions
Some digestive conditions and surgeries can affect B12 absorption.
4. Certain Medications
Some medications can affect vitamin B12 absorption or levels. If you take medication regularly, discuss long-term supplement use with your healthcare professional rather than changing treatment yourself.
5. Age-Related Changes
Some older adults may have reduced ability to absorb B12 from food, making nutritional assessment more important.
Who Is More Likely to Develop B12 Deficiency?
Vegetarians & Vegans
Natural vitamin B12 is found mainly in animal-derived foods, so people avoiding these foods need reliable fortified foods or supplementation.
Older Adults
Changes in digestion and absorption can increase the risk of inadequate B12 status.
People With Absorption Problems
Certain stomach and intestinal conditions can interfere with B12 absorption.
People Taking Certain Medicines
Some long-term medications may affect B12 status. Discuss concerns with your healthcare professional.
Taking Multiple Vitamins?
Don’t assume every vitamin supplement is harmless just because it is sold over the counter. Learn how high doses and overlapping supplements can become a problem.
Read Vitamin Safety GuideBest Food Sources of Vitamin B12
Vitamin B12 is naturally found in a range of animal-derived foods. Some plant-based foods are fortified with B12 and can also contribute to intake.
Fish & Seafood
Several types of fish and seafood can provide vitamin B12.
Meat & Poultry
Meat and poultry are naturally occurring sources of vitamin B12.
Eggs
Eggs contain vitamin B12 and can contribute to dietary intake.
Dairy Products
Milk, yogurt and other dairy foods can provide vitamin B12.
Fortified Foods
Some breakfast cereals, plant-based drinks and other foods are fortified with vitamin B12. Always check the nutrition label.
Supplements
B12 supplements can be useful when dietary intake or absorption is inadequate, particularly when recommended by a healthcare professional.
Can Vegetarians and Vegans Get Enough B12?
Yes, but they need a reliable source.
Because vitamin B12 is naturally concentrated in animal-derived foods, people following vegetarian or vegan diets should pay particular attention to fortified foods and appropriate supplementation.
Simply eating more fruits, vegetables and grains does not guarantee adequate B12 intake.
If you follow a plant-based diet, look at the labels of fortified foods and discuss an appropriate B12 strategy with a healthcare professional or registered dietitian.
Vitamin B12 Supplements: Do You Need One?
Not everyone needs a B12 supplement.
Supplementation may be appropriate when dietary intake is insufficient, a deficiency has been identified, or absorption is impaired.
However, taking B12 simply because you feel tired is not a reliable way to determine whether you need it.
A healthcare professional can consider your symptoms, diet, medical history and appropriate laboratory testing when deciding whether supplementation is needed.
Can You Take Too Much Vitamin B12?
Vitamin B12 is generally considered to have a low potential for toxicity compared with some other vitamins. However, that does not mean everyone should take high-dose supplements without a reason.
The right supplement and dose depend on why you are taking it and whether a deficiency or absorption issue exists.
If you are already taking a multivitamin, B-complex and other supplements, check whether B12 appears in more than one product.
You can read our guide on supplement overlap here: Do You Really Need a Daily Multivitamin?
B12 Deficiency vs. Feeling Tired All the Time
This is an important distinction.
Feeling tired after a poor night’s sleep does not mean you have a vitamin deficiency. Likewise, fatigue caused by stress, an intense work schedule or inadequate recovery should not automatically be treated with supplements.
Persistent fatigue can have many causes, including sleep problems, anemia, thyroid conditions, infections, medication effects and other health issues.
That is why treating yourself with multiple vitamins without understanding the underlying cause can delay proper evaluation.
How Is Vitamin B12 Deficiency Diagnosed?
A healthcare professional may consider your symptoms, dietary pattern, medical history and blood tests when evaluating possible B12 deficiency.
The exact tests used can vary depending on the situation. A B12 blood measurement may be part of the evaluation, and additional tests may sometimes be needed to clarify the result.
Do not start high-dose supplementation solely to avoid getting tested if a deficiency is suspected. Professional guidance can help determine the appropriate next step.
Why Early Attention Matters
Some effects of prolonged B12 deficiency can involve the nervous system. This is one reason persistent symptoms should not be ignored.
If you notice ongoing numbness, tingling, balance problems, unusual weakness or cognitive changes, speak with a healthcare professional.
Simple Ways to Support Healthy B12 Intake
- Include reliable B12-containing foods in your diet.
- If you follow a vegetarian or vegan diet, use reliable fortified foods or an appropriate supplement.
- Read supplement labels before adding another B-complex or multivitamin.
- Don’t assume fatigue automatically means you need B12.
- Discuss persistent symptoms with a healthcare professional.
- If you have a condition affecting absorption, ask whether you need monitoring.
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Frequently Asked Questions
What are the first signs of vitamin B12 deficiency?
Possible signs include tiredness, weakness, pale skin, a sore tongue, numbness or tingling and changes in balance or thinking. Symptoms vary and are not specific to B12 deficiency.
What foods are high in vitamin B12?
Fish, seafood, meat, poultry, eggs and dairy products can provide vitamin B12. Some fortified foods also contain B12.
Can vegetarians get enough vitamin B12?
They can, but they need a reliable source. Fortified foods and appropriate supplements can help provide B12 when natural dietary sources are limited.
Can vitamin B12 deficiency cause tiredness?
Yes, B12 deficiency can contribute to fatigue, particularly when it causes anemia. However, tiredness has many possible causes and should not automatically be attributed to B12 deficiency.
Can B12 deficiency cause numbness and tingling?
Yes. Vitamin B12 deficiency can affect the nervous system and may cause numbness or tingling. Persistent neurological symptoms should be medically evaluated.
Should I take B12 if I feel tired?
Not necessarily. Tiredness can have many causes. If it is persistent or unexplained, speak with a healthcare professional rather than starting multiple supplements on your own.
Can I take B12 with a multivitamin?
Many multivitamins already contain B12. Check the label before adding another supplement to avoid unnecessary duplication.
How do I know if I have B12 deficiency?
Symptoms alone cannot confirm deficiency. A healthcare professional can evaluate your symptoms, diet and medical history and decide whether blood testing or other evaluation is appropriate.
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The Bottom Line
Vitamin B12 is essential for healthy blood cells, DNA production and normal nervous-system function. A deficiency can develop because of inadequate dietary intake, absorption problems, certain health conditions or other factors.
The most important thing to remember is that symptoms such as tiredness, weakness or tingling do not prove that you have a B12 deficiency.
If you are concerned, focus on reliable food sources, check your supplement labels and speak with a healthcare professional about whether testing or supplementation is appropriate.
And if you’re already taking several vitamins, don’t forget to check our guide on vitamin and supplement safety before adding another product.
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