Vitamin B-12 Deficiency Anemia

What is vitamin B-12 deficiency anemia?

Vitamin B-12 deficiency anemia is a condition in which your body doesn't have enough healthy red blood cells because of a lack of vitamin B-12. This vitamin is needed to make red blood cells. These cells carry oxygen to all parts of your body. Without enough red blood cells, your tissues and organs don’t get enough oxygen. Without enough oxygen, your body can’t work as well.

Folic acid is also called folate. It is another B vitamin. Either a lack of vitamin B-12 or a lack of folate causes a type of anemia called megaloblastic anemia. With these types of anemia, the red blood cells don’t develop normally. They are very large. And they are shaped like an oval. Healthy red blood cells are round. This difference in shape causes the bone marrow to make fewer red blood cells. In some cases, the red blood cells die sooner than normal.

What causes vitamin B-12 deficiency anemia?

Vitamin B-12 deficiency anemia is more common in people whose families come from northern Europe. It is caused by:

  • Lack of intrinsic factor. Intrinsic factor is a protein made in the stomach. It is needed to absorb vitamin B-12. This type of B-12 deficiency anemia is called pernicious anemia.

  • Inability to absorb vitamin B-12. Surgery that removes or bypasses the end of the small intestine may be one reason that B-12 can't be absorbed. Other causes include changes in the small bowel that limit how much vitamin B-12 you can absorb.

The inability to make intrinsic factor may be caused by several things, such as:

  • Chronic gastritis

  • Surgery to remove all or part of the stomach (gastrectomy)

  • An autoimmune condition, where the body attacks its own tissues

Other types of megaloblastic anemia may be linked to type 1 diabetes, thyroid disease, and a family history of the disease.

Who is at risk for vitamin B-12 deficiency anemia?

Risk factors for vitamin B-12 deficiency anemia include:

  • A family history of the disease

  • Surgery that removes part or all of your stomach or intestine

  • Autoimmune diseases, including type 1 diabetes

  • Crohn's disease

  • HIV

  • Some medicines

  • Strict vegetarian or vegan diets

  • Older age

What are the symptoms of vitamin B-12 deficiency anemia?

Each person’s symptoms may vary. Symptoms may include:

  • Weak muscles

  • Numb or tingling feeling in hands and feet

  • Trouble walking

  • Nausea

  • Decreased appetite

  • Weight loss

  • Irritability

  • Lack of energy or tiring easily (fatigue)

  • Diarrhea

  • Smooth and tender tongue

  • Fast heart rate

The symptoms of vitamin B-12 anemia may look like other blood conditions or health problems. Always see your healthcare provider for a diagnosis.

How is vitamin B-12 deficiency anemia diagnosed?

This type of anemia is usually found during a health exam through a routine blood test. Your healthcare provider will take your health history and give you a physical exam.

You may also need other blood tests. You may also have other assessment procedures, such as a bone marrow biopsy.

How is vitamin B-12 deficiency anemia treated?

Vitamin B-12 deficiency anemia and folate deficiency anemia often occur together and can be hard to tell apart. Treatment may include vitamin B-12 pills, nasal spray, or shots (injections) for more serious deficiency or folic acid pills.

Foods that are rich in folic acid include:

  • Orange juice

  • Oranges

  • Romaine lettuce

  • Spinach

  • Liver

  • Rice

  • Barley

  • Sprouts

  • Wheat germ

  • Soy beans

  • Leafy green vegetables

  • Beans

  • Peanuts

  • Broccoli

  • Asparagus

  • Peas

  • Lentils

  • Chickpeas (garbanzo beans)

Foods that are rich in both folic acid and vitamin B-12 include:

  • Eggs

  • Meat

  • Poultry

  • Milk

  • Shellfish

  • Fortified cereals

  • Fortified milk substitutes

Taking folic acid by mouth works better than eating foods rich in folic acid. Vitamin B-12 is not as well absorbed by mouth as by injection.

Living with vitamin B-12 deficiency anemia

Depending on the cause of your vitamin B-12 deficiency, you may need to take vitamin B-12 supplements for the rest of your life. These may be pills or shots. This may seem difficult. But it will let you live a normal life without symptoms.

If your deficiency is from a restrictive diet, you may want to work with a nutritionist. They can help make sure that you get enough vitamin B-12 and other vitamins. Tell your healthcare provider about any symptoms and follow your treatment plan.

Key points about vitamin B-12 deficiency anemia

  • With this condition, your body does not have enough healthy red blood cells because of a lack (deficiency) of vitamin B-12.

  • It is 1 of several types of megaloblastic anemia. This condition is when the red blood cells don't develop normally. They become very large and oval shaped.

  • Without enough red blood cells, your tissues and organs don’t get enough oxygen. Without enough oxygen, your body can’t work as well.

  • Symptoms include weak muscles, numbness, trouble walking, nausea, weight loss, irritability, fatigue, and increased heart rate.

  • Treatment may include vitamin B-12 supplements. It is also important to eat a well-balanced diet that is rich in Vitamin B-12.

Next steps

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

  • Know the reason for your visit and what you want to happen.

  • 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 name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new directions your provider gives you.

  • Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.

  • Ask if your condition can be treated in other ways.

  • Know why a test or procedure is recommended and what the results could mean.

  • Know what to expect if you do not take the medicine or have the test or procedure.

  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.

  • Know how you can contact your healthcare provider if you have questions.

Online Medical Reviewer: Jessica Gotwals RN BSN MPH
Online Medical Reviewer: Rita Sather RN
Online Medical Reviewer: Todd Gersten MD
Date Last Reviewed: 5/1/2023
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