What are the signs of vitamin B12 deficiency?

Jill A. Grimes, MD
Family Medicine
Signs of vitamin B12 deficiency include fatigue, memory loss, and funny sensations -- paresthesias -- often on the feet or hands. If the B12 deficiency is significant, lab tests will show enlarged red blood cells and low total red blood cell count (macrocytosis and anemia, in medical language). If you take acid-blocking medications daily and are feeling run down, ask your doctor to check your vitamin B12 level.
Dr. David L. Katz, MD, MPH
Preventive Medicine
Common manifestations of vitamin B12 deficiency include weakness, numbness and tingling, fatigue, dizziness, swelling and irritation of the mouth and tongue and irritability. Anemia can develop, but a high intake of folate can compensate for a deficiency of vitamin B12 and prevent anemia.

The most serious manifestation of B12 deficiency is impaired brain function, due to the effects of B12 on nerve cells. Advanced B12 deficiency causes dementia severe enough to resemble Alzheimer’s disease. Generally, though, the dementia caused by B12 deficiency is completely reversible with supplementation. While folate can prevent B12-deficient anemia, it cannot prevent the dementia -- only B12 itself can do that job.
Vitamin B12 deficiency may result in anemia, which can cause symptoms including light-headedness, weakness, shortness of breath, pale skin, difficulty concentrating and fatigue. A chronic shortage of vitamin B12 may also cause nerve damage that leads to tingling and numbness in hands and feet.

Vitamin B12, along with another B vitamin called folate, is essential for the formation of normal red blood cells in the body. Red blood cells are needed to transport oxygen throughout the body. Vitamin B12 also is needed for the repair of tissues and cells and for your body's genetic material, or DNA.

Consult your doctor if you think you might be at risk for vitamin B12 deficiency.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.