Vitamin B12 plays an important role in producing healthy red blood cells, maintaining the nervous system, and supporting normal DNA production. When the body does not get or absorb enough vitamin B12, deficiency can develop gradually.
Because the symptoms can be mild at first, they are sometimes mistaken for stress, aging, lack of sleep, or other common health problems. Recognizing the possible warning signs can help you know when it may be worth talking to a healthcare professional.
1. Persistent Fatigue and Weakness
Feeling unusually tired or weak is one of the possible signs of vitamin B12 deficiency.
Vitamin B12 is needed for normal red blood cell production. A significant deficiency can contribute to certain types of anemia, which may cause fatigue, weakness, dizziness, or shortness of breath.
However, tiredness is extremely common and can have many causes, including poor sleep, iron deficiency, thyroid problems, infections, and other medical conditions.
2. Numbness or Tingling
A sensation of pins and needles, numbness, or tingling in the hands or feet can occur with vitamin B12 deficiency.
This happens because prolonged B12 deficiency can affect the nervous system. Unlike some symptoms that disappear quickly, neurological problems associated with B12 deficiency can become more serious if the deficiency remains untreated.
Unexplained or persistent numbness and tingling should therefore be discussed with a healthcare professional.
3. Problems With Balance or Walking
More advanced vitamin B12 deficiency can affect coordination and balance.
A person may feel unsteady while walking or have difficulty maintaining their balance. These symptoms can have many other causes, so they should not automatically be attributed to a vitamin deficiency.
Sudden difficulty walking, severe weakness, or loss of coordination requires urgent medical assessment.
4. Pale or Yellowish Skin
People with vitamin B12 deficiency may develop unusually pale skin. In some cases, the skin can have a slightly yellowish appearance because of changes associated with red blood cell breakdown.
Changes in skin color can have numerous causes, so medical evaluation is important if the change is persistent or unexplained.
5. A Swollen or Sore Tongue
Vitamin B12 deficiency can sometimes cause inflammation of the tongue, known as glossitis.
The tongue may appear unusually smooth, red, swollen, or sore. Some people may also experience a burning sensation in the mouth.
6. Changes in Memory or Thinking
Difficulty concentrating, memory problems, or feeling mentally “foggy” can sometimes occur with vitamin B12 deficiency.
These symptoms are not specific to B12 deficiency and can also be associated with stress, sleep problems, medications, depression, and many other conditions.
If cognitive changes are persistent or worsening, a healthcare professional can help determine the underlying cause.
7. Mood Changes
B12 deficiency may be associated with mood changes, including irritability, low mood, or symptoms of depression.
These symptoms have many possible causes, so they should not be used on their own to diagnose vitamin B12 deficiency.
Who Is at Risk of Vitamin B12 Deficiency?
Some people have a higher risk of developing B12 deficiency, including those who:
- Follow a strict vegan diet without reliable B12 sources or supplementation
- Have certain digestive or absorption disorders
- Have undergone some gastrointestinal surgeries
- Take certain medications that can interfere with B12 absorption
- Are older adults
- Have conditions that affect the absorption of nutrients
Having a risk factor does not necessarily mean that a person is deficient.
How Is Vitamin B12 Deficiency Diagnosed?
Symptoms alone cannot reliably diagnose vitamin B12 deficiency.
A healthcare professional may consider your symptoms, diet, medical history, medications, and risk factors and may order blood tests to assess vitamin B12 status and related markers.
If a deficiency is confirmed, treatment depends on its cause. Some people may need dietary changes or oral B12 supplements, while others may require a different form of treatment, particularly when absorption is impaired.
Can You Prevent Vitamin B12 Deficiency?
For many people, getting enough vitamin B12 through a balanced diet can help prevent deficiency.
Natural sources include foods such as fish, meat, eggs, dairy products, and other animal-derived foods. Many foods are also fortified with vitamin B12.
People who avoid animal products may need fortified foods or a reliable B12 supplement to meet their nutritional needs.
It is best to discuss supplementation with a healthcare professional if you are at increased risk or have symptoms of deficiency.
The Bottom Line
Vitamin B12 deficiency can develop gradually, and symptoms such as fatigue, tingling, balance problems, tongue changes, and difficulty concentrating can easily be overlooked.
These symptoms do not necessarily mean that you have a B12 deficiency, but persistent or unexplained symptoms deserve attention. Early diagnosis and appropriate treatment can help prevent complications, particularly those affecting the nervous system.
If you suspect that you may be deficient, speak with a healthcare professional rather than relying solely on supplements or self-diagnosis.