Vitamin B12 Deficiency

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What is vitamin B12 deficiency?

Vitamin B12 deficiency is a condition in which the body has inadequate stores of vitamin B12. This vitamin is essential for many aspects of health, including the production of red blood cells. Healthy numbers of red blood cells are critical for delivering oxygen and nutrients to the body’s cells and tissues.

Vitamin B12 is a water-soluble vitamin that must be ingested daily and absorbed effectively by the digestive tract in order to maintain optimal health. Most people get enough vitamin B12 by eating a variety of foods. Those that naturally contain vitamin B12 include lean red meats, poultry, fish, brewer’s yeast, and dairy products, such as milk, cheese, and yogurt. Vitamin B12 is also added to some breakfast cereals, breads, and other fortified food products.

Vitamin B12 deficiency is most common in people who have a disease or condition in which the body is unable to absorb vitamin B12 from ingested foods. It is also relatively common in older adults. One in 31 adults age 51 years and older has a vitamin B12 deficiency, according to the Centers for Disease Control and Prevention (Source: CDC).

Less commonly, vitamin B12 deficiency results from an inadequate intake of foods that contain vitamin B12.

Untreated vitamin B12 deficiency can lead to serious complications, such as anemia, nerve damage, and growth abnormalities. Seeking regular medical care and following your treatment plan can help reduce the risk of serious complications from vitamin B12 deficiency.

What are the symptoms of vitamin B12 deficiency?

The symptoms vary depending on the individual, the underlying cause, the severity of B12 deficiency, and other factors. In some cases, the symptoms of vitamin B12 deficiency can be vague, take years to develop, or may not be noticeable immediately.

Some symptoms of vitamin B12 deficiency are due to a decreased production of red blood cells, which are necessary to carry vital oxygen to the body’s cells and tissues. Symptoms of vitamin B12 deficiency can affect the gastrointestinal tract, the nervous system, and the cardiovascular system. Symptoms of vitamin B12 deficiency include:

    What causes vitamin B12 deficiency?

    Vitamin B12 deficiency is most often caused by an inability of the body to properly digest and absorb vitamin B12. The inability to absorb vitamin B12 can be caused by diseases and conditions including:

    • Atrophic gastritis (a condition in which the stomach lining is inflamed and becomes thin)

    • Autoimmune endocrinopathiy (diabetes, hypothyroidism)

    • Celiac disease (sensitivity to gluten from wheat and other grains, causing intestinal damage)

    • Crohn’s disease (an inflammatory bowel disease that can affect any part of the intestine)

    • Fish tapeworm

    • Pernicious anemia (a result of atrophic gastritis with poor B12 absorption)

    • Surgical removal of a portion of the stomach or small intestine, such as with bariatric surgery

    In addition, some medications that treat diabetes, acid reflux, and peptic ulcers, for example, can affect how well your body can absorb vitamin B12.
    Less commonly, vitamin B12 deficiency can occur as a result of not eating enough foods that contain vitamin B12. Foods that contain vitamin B12 include lean red meats, poultry, fish, brewer’s yeast, and dairy products, such as milk, cheese, and yogurt.

    What are the risk factors for vitamin B12 deficiency?

    A number of factors are thought to increase your chances of developing vitamin B12 deficiency:

    • Atrophic gastritis

    • Being an older adult

    • Celiac disease

    • Crohn’s disease

    • Following a strict vegan or vegetarian diet

    • Intestinal bacterial or tapeworm infestation

    • Pernicious anemia

    • Surgical removal of a portion of the small intestine   

    People at risk include:

    • Breast-feeding infants of a vegetarian or vegan mother

    • Postoperative gastric bypass surgery patients

    • Pregnant or breast-feeding women who are vegans or strict vegetarians

    How can you reduce your risk for vitamin B12 deficiency?

    Most cases of vitamin B12 deficiency that are due to the body’s inability to properly absorb the vitamin through the digestive tract can be prevented only by successful treatment of the underlying cause. However, you may be able to lower your risk of vitamin B12 deficiency by:

    • Eating a diet that includes a sufficient amount of vitamin B12, which is found in lean red meats, poultry, fish, and dairy products, such as milk, cheese, and yogurt. Various food products such as breakfast cereals are also fortified with vitamin B12.

    • Taking vitamin B12 supplements as recommended if you are at high risk for developing vitamin B12 deficiency, such as if you follow a vegan diet or have celiac disease or Crohn’s disease

    Keep in mind that some medicines that treat diabetes, acid reflux, and peptic ulcer disease can affect how well your body absorbs vitamin B12. Most important, talk with your health care provider about any supplements, prescription medications, and over-the-counter medications you take. They can tell you if any supplements you take could interfere or interact with your prescription medications.

    How is vitamin B12 deficiency treated?

    Vitamin B12 deficiency is treatable. With prompt diagnosis and treatment, you can expect to have a good prognosis and a minimal risk of developing serious complications, such as nerve damage, anemia, or dementia.

    Treatment of vitamin B12 deficiency involves replacing the body’s depleted stores of vitamin B12. This generally includes:

    • A series of vitamin B12 injections, which may need to be a life-long treatment in cases in which the body cannot absorb vitamin B12

    • Oral vitamin B12 replacement therapy may also be prescribed. Vitamin B12 may also be given through a nasal spray, or in a sublingual form that is absorbed under the tongue.

    • Eating more red meats, poultry, fish, and dairy products

    • Treating underlying causes of vitamin B12 deficiency

    What are the potential complications of vitamin B12 deficiency?

    Complications of vitamin B12 deficiency can be serious. You can treat vitamin B12 deficiency and minimize the risk of complications by following the treatment plan that you and your health care professional design specifically for you.

    Serious complications of vitamin B12 deficiency include:

    • Anemia

    • Abnormalities in growth and development

    • Dementia

    • Depression

    • Increased risk for gastric cancer

    • Nerve damage, possibly permanent

    • Progression of symptoms

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    Medical Reviewer: William C. Lloyd III, MD, FACS
    Last Review Date: 2021 Jan 20
    THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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