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Vitamin B12 Deficiency

Medically reviewed by Last updated on Mar 5, 2023.

What is vitamin B12 deficiency?

Vitamin B12 deficiency is a low level of vitamin B12 in your body. Vitamin B12 is only found in foods that come from animal sources such as fish, beef, dairy products, and eggs. Vitamin B12 deficiency should be treated as early as possible. Without treatment, it can cause permanent nerve damage over time.

What causes or increases my risk for vitamin B12 deficiency?

  • You eat few or no foods that contain vitamin B12. Vegans and other vegetarians are at increased risk for vitamin B12 deficiency. Infants born to or breastfed by a woman with a vitamin B12 deficiency may also have low levels of vitamin B12.
  • Your body cannot absorb enough vitamin B12 from foods. Your body may not absorb enough vitamin B12 if you are elderly or you have certain medical conditions. These include diabetes, Celiac disease, and Crohn disease. You may also have trouble absorbing vitamin B12 if you have had gastrointestinal surgery such as gastric bypass or gastrectomy.

What are the signs and symptoms of vitamin B12 deficiency?

You may not have any signs or symptoms, or you may have any of the following:

  • Fatigue or weakness
  • Loss of appetite or weight loss
  • Constipation
  • Depression, confusion, dementia, or poor memory
  • Mouth or tongue soreness
  • Trouble keeping your balance
  • Numbness or tingling in your hands or feet
  • In infants and children, irritability, poor growth, developmental delay, or movement disorders

How is vitamin B12 deficiency diagnosed?

Your healthcare provider will ask about your signs and symptoms and examine you. He or she may also order blood tests to check the level of vitamin B12 in your body or to find the cause of your deficiency.

How is vitamin B12 deficiency treated?

  • For low intake deficiency , you may need to eat more foods that contain or are fortified with vitamin B12. You may also need to take an over-the-counter supplement.
  • For low absorption deficiency , you may need several high doses of vitamin B12 to increase your levels. These doses of vitamin B12 may be given as a shot or pill. You may need to take these vitamin B12 supplements for the rest of your life.

Treatment options

The following list of medications are in some way related to or used in the treatment of this condition.

View more treatment options

Which foods are good sources of vitamin B12?

Sources of Vitamin B
  • 3 ounces of cooked clams, 84.1 mcg
  • 3 ounces of cooked beef liver, 70.7 mcg
  • Fortified breakfast cereals, 1.5 to 6 mcg per serving
  • 3 ounces of salmon, rainbow trout, or canned tuna fish, 2.5 to 4.8 mcg
  • 3 ounces of top sirloin beef, 1.4 mcg
  • 1 cup of milk or yogurt, 1.1 to 1.2 mcg
  • 1 cup of a soy milk product, 0.9 to 3.3 mcg
  • 1 ounce of a meat substitute, 0.5 to 1.2 mcg
  • 1 ounce Swiss cheese, 0.9 mcg
  • 1 large egg, 0.6 mcg

How much vitamin B12 do I need each day?

  • Infants 0 to 12 months: 0.4 micrograms (mcg) to 0.5 mcg
  • Children 1 to 3 years: 0.9 mcg
  • Children 4 to 8 years: 1.2 mcg
  • Children 9 to 13 years: 1.8 mcg
  • Children over 14 years and adults: 1.8 mcg
  • Pregnant women and adolescents (over 14 years): 2.6 mcg
  • Breastfeeding women and adolescents (over 14 years): 2.8 mcg

When should I call my doctor?

  • You continue to have symptoms, or your symptoms get worse.
  • You have questions or concerns about your condition or care.

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your healthcare providers to decide what care you want to receive. You always have the right to refuse treatment. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.