What is Vitamin B12 Deficiency?

Updated at: Jan 18, 2013
What is Vitamin B12 Deficiency?

Vitamin B12 deficiency is a condition in which body has inadequate stores of vitamin B12. This vitamin is essential for several vital functions of the body. Vitamin B12 deficiency occurs mostly in people who have a disease or condition in which th

Dr Poonam Sachdev
Blood DiseasesWritten by: Dr Poonam SachdevPublished at: Jun 19, 2012

Vitamin B12 deficiency is a condition in which the body has inadequate stores of vitamin B12. This vitamin is essential for several vital functions of the body such as:

  • DNA production and repair.
  • Synthesis of haemoglobin.
  • Proper neural production and communication.
  • Metabolism.

B12 deficiency is more common in older adults. According to studies, about 1 in 31 adults above 51 years of age has vitamin B12 deficiency and around 1 in 10 above 75 has vitamin B12 deficiency.

Vitamin B12 is a water-soluble vitamin that is present in adequate amounts in certain foods. Foods which contain B12 include meat, poultry, seafood, milk, cheese, and eggs. Seafood, such as shrimp, scallops and fish such as snapper, halibut and salmon, are also rich in this vitamin. Dairy products such as cow's milk and yoghurt which are natural sources of vitamin B12, are also good sources of vitamin B12. Vegetarian food is deficient in vitamin B12. People who don't eat animal products should take a B12-containing multivitamin, according to health experts. A daily supplement of 5 mcg to 10 mcg is adequate to prevent deficiency of this vitamin.

Causes of vitamin B12 Deficiency

Vitamin B12 deficiency occurs mostly in people who have a disease or condition in which the body is unable to properly digest and absorb vitamin B12. Inability to absorb vitamin B12 can be caused by diseases such as chronic GI illnesses (such as Crohn's disease and coeliac disease, upper GI surgery (including gastrectomy, gastric bypass, or iliectomy), and pernicious anaemia. Pernicious anaemia a condition in which B12 is not absorbed, is the most common cause of vitamin B12 deficiency and affects about 1 in 10,000 people.
Not as commonly, the deficiency is caused by inadequate intake of foods that contain vitamin B12. Inadequate intake, because of low consumption of animal-source foods, is probably the major cause of low serum vitamin B-12 in younger adults and in people from developing countries.

Symptoms of Vitamin B12 Deficiency

Symptoms of vitamin B12 deficiency depend on the severity of deficiency. Mild deficiency may cause non-specific symptoms but as deficiency worsens, it may damage neurological cells and cause neurological symptoms. Some symptoms of B12 deficiency include:

  • Fatigue, weakness, or tiredness.
  • Light-headedness or shortness of breath.
  • Rapid heartbeat and breathing.
  • Pale skin (pallor) or white spots on the skin (due to release of melatonin).
  • Sore tongue.
  • Easy bruising or bleeding, including bleeding gums.
  • Poor memory, hard to focus with the complete inability to concentrate.
  • Tingling or numbness in fingers and toes.
  • Difficulty in walking.
  • Depression, confusion, paranoia and other behavioural disorders.
  • Memory loss, disorientation, and dementia.


Vitamin B12 deficiency is very treatable with medications. Early diagnosis and treatment improves prognosis and can prevent serious complications, such as nerve damage, anaemia, or dementia.

Vitamin B12 deficiency is treated with supplements to replace the body’s depleted stores of vitamin B12. Vitamin B12 can be given as oral vitamin B12 supplement, vitamin B12 Injections, intranasal vitamin B12 (in the nose) and sublingual vitamin B12 (placed under the tongue). In addition to vitamin B12 supplements, eating foods rich in vitamin B12, and iron and folic acid supplements is essential.


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