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Symptoms of Vitamin B12 Deficiency

A deficiency of vitamin B12 can lead to anemia. A mild deficiency may cause no symptoms. But if untreated, it may progress and cause symptoms such as:

  • Weakness, tiredness, or lightheadedness
  • Heart palpitations and shortness of breath
  • Pale skin
  • A smooth tongue
  • Constipation, diarrhea, a loss of appetite, or gas 
  • Nerve problems like numbness or tingling, muscle weakness, and problems walking
  • Vision loss
  • Mental problems like depression, memory loss, or behavioral changes 

If you think you have symptoms of vitamin B12 deficiency, you can ask your doctor for a blood test.

Infants who are born to vegan mothers and exclusively breastfed  are at risk for anemia, developmental delays, weakness, and failure to thrive. 

Treatment for Vitamin B12 Deficiency

If you have pernicious anemia or a problem with its absorption, you'll need to replace vitamin B12 by injection initially and then continued injections, high doses of an oral replacement, or nasal therapy for life.

If the issue is that you don't eat animal products, you can change your diet to include vitamin B12-fortified grains, a supplement or B12 injections, or a high-dose oral vitamin B12 if you are deficient.

The elderly should take a daily B12 supplement or a multivitamin that contains B12.

For most people, treatment resolves the problem. But any nerve damage that happened due to the deficiency could be permanent.

Preventing Deficiency Problems

Most people can prevent vitamin B12 deficiency by eating enough meat, poultry, seafood, dairy products, and eggs.

If you don't eat animal products, or you have a medical condition that limits how well your body absorbs nutrients, experts recommend taking a B12-containing multivitamin and eating breakfast cereal fortified with vitamin B12.

If you're using vitamin B12 supplements, let your doctor know, so he or she can make sure they won't affect any medicines you're taking.

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