Vitamin B12 Deficiency
(Vitamin B12 Deficiency; Macrocytic Achylic Anemia)
How to Say It: Vite-ah-min bee-twelv di-fish-ens-ee
by Cynthia M. Johnson, MA
Vitamin B12 deficiency is a low level of vitamin B12 in the body. This vitamin is found in foods like seafood, dairy, and eggs. The body uses it to make red blood cells, nerves, DNA, and carry out other functions.
Not getting enough of this vitamin can lead to anemia. This is a low level of red blood cells. It can also lead to problems with the nervous system.
Vitamin B12 deficiency can be caused by:
This problem is more common in older adults. Other things that may raise the risk are:
Problems vary from person to person. They may also get worse over time. Common ones are:
The doctor will ask about your symptoms and health history. A physical exam will be done. You may also be asked about your diet.
Your level of vitamin B12 will be tested. This can be done with blood tests.
More tests may be done to look for a cause.
Any underlying causes may be treated.
The goal of treatment is to increase vitamin B12 levels. This can be done with vitamin B12 replacement therapy.
The risk of this problem may be lowered by eating foods that contain vitamin B12, such as seafood, dairy, and eggs. Supplements may need to be taken by people who are at risk for deficiency, such as vegetarians.
Family Doctor—American Academy of Family Physicians
National Institutes of Health Office of Dietary Supplements
College of Family Physicians of Canada
Dietary supplement fact sheet: vitamin D. Office of Dietary Supplements website. Available at: https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional. Accessed February 5, 2021.
Vitamin B12 deficiency. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/vitamin-b12-deficiency. Accessed February 5, 2021.
Last reviewed December 2020 by EBSCO Medical Review Board Dianne Scheinberg Rishikof MS, RD, LDN
Last Updated: 2/4/2021