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Anemia of B12 Deficiency

What is vitamin B12 deficiency anemia?

Vitamin B12 deficiency anemia is one of several types of megaloblastic anemia. Megaloblastic anemia is a type of anemia characterized by very large red blood cells. Also, the inner contents of each cell are not completely developed. This causes the bone marrow to produce fewer cells, and sometimes the cells die earlier than normal. Instead of being round or disk-shaped, the red blood cells can be oval.

Vitamin B12 deficiency anemia and folate deficiency anemia are the most common causes of megaloblastic anemia. Pernicious anemia is a subtype of B12 deficiency.

What causes vitamin B12 deficiency anemia?

Vitamin B12 deficiency anemia is more common in people of northern European descent. The condition is caused by one of the following:

  • Vitamin B12 deficiency caused by a lack of intrinsic factor in stomach secretions. Intrinsic factor is necessary for absorption of vitamin B12. This type of B12 deficiency anemia is technically pernicious anemia.
  • Vitamin B12 deficiency caused by surgery that removes or bypasses the end of the small intestine where vitamin B12 is absorbed. This type is not technically pernicious anemia, but some people will use this name for all kinds of anemia due to vitamin B12 deficiency.
The inability to make intrinsic factor may be the result of several factors, such as chronic gastritis, gastrectomy (removal of all or part of the stomach), or an autoimmune condition (the body attacks its own tissues). Other types of megaloblastic anemia may be associated with type 1 diabetes, thyroid disease, and a family history of the disease.

Who is at risk for vitamin B12 deficiency anemia?

Risk factors for vitamin B12 deficiency anemia include:

  • A family history of the disease
  • Removal of part or all of your stomach or intestine
  • Autoimmune disease including type 1 diabetes
  • Crohn's disease
  • HIV
  • Some medications
  • Strict vegetarian diets
  • Being elderly

What are the symptoms of vitamin B12 deficiency anemia?

The following are the most common symptoms for megaloblastic anemia. However, each person may experience symptoms differently. Symptoms may include:

  • Weak muscles
  • Numbness or tingling in hands and feet
  • Difficulty walking
  • Nausea
  • Decreased appetite
  • Weight loss
  • Irritability
  • Lack of energy or tiring easily (fatigue)
  • Diarrhea
  • Smooth and tender tongue
  • Increased heart rate

The symptoms of megaloblastic anemia may look like other blood conditions or medical problems. Always consult your health care provider for a diagnosis.

How is vitamin B12 deficiency anemia diagnosed?

This type of anemia is usually found during a medical exam through a routine blood test. In addition to a complete medical history and physical exam, diagnostic procedures for megaloblastic anemia may include additional blood tests and other evaluation procedures, such as a bone marrow biopsy.

How is vitamin B12 deficiency anemia treated?

Specific treatment for vitamin B12 deficiency anemia will be determined by your health care provider based on:

  • Your age, overall health, and medical history
  • Extent of the disease
  • Your tolerance for specific medications, procedures, or therapies
  • Expectations for the course of the disease
  • Your opinion or preference

Vitamin B12 deficiency anemia and folate deficiency anemia often occur together and can be difficult to tell apart. Treatment may include vitamin B12 injections and folic acid pills. Foods that are rich in folic acid include the following:

  • Orange juice
  • Oranges
  • Romaine lettuce
  • Spinach
  • Liver
  • Rice
  • Barley
  • Sprouts
  • Wheat germ
  • Soy beans
  • Green, leafy vegetables
  • Beans
  • Peanuts
  • Broccoli
  • Asparagus
  • Peas
  • Lentils
  • Chickpeas (garbanzo beans)

Foods that are rich in folic acid and vitamin B12 include the following:

  • Eggs
  • Meat
  • Poultry
  • Milk
  • Shellfish
  • Fortified cereals

Taking folic acid by mouth is more effective than eating foods rich in folic acid. B12 is not as well absorbed by mouth as per injection.

Living with vitamin B12 deficiency anemia

Depending on the cause of your vitamin B12 deficiency, it may be necessary to receive vitamin B12 supplementary for the rest of your life. Although this may seem inconvenient, this allows you to live a normal life without symptoms. If your deficiency is due to a restrictive diet, you may want to work with a nutritionist to assure that you have an adequate intake of vitamin B12 and other vitamins. It is important to inform your health care provider of any symptoms and to follow your treatment plan.

Key points about vitamin B12 deficiency anemia

  • Vitamin B12 deficiency anemia is one of several types of megaloblastic anemia.
  • It is characterized by very large red blood cells with inner contents that are not completely developed.
  • Symptoms include weak muscles, numbness, difficulty walking, nausea, weight loss, irritability, fatigue and increased heart rate.
  • Treatment may include vitamin B12 injections.
  • It is also important to eat a well-balanced diet.

Next steps

Tips to help you get the most from a visit to your health care provider:

  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the names of new medicines, treatments, or tests, and any new instructions your provider gives you.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.

Medical Reviewers:

  • Fetterman, Anne, RN, BSN
  • Freeborn, Donna, PhD, CNM, FNP