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Vitamin B12 Deficiency

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23 Aug, 2018

Vitamin B12 (or Cobalamin) is one of the most common nutritional deficiencies. It is caused when the body does not get enough vitamin B12 or fails to absorbs it efficiently. Vitamin B12 is important for DNA and protein metabolism, which is the foundation for every organ system in the body to function at its finest. Some of the functions include the formation of red blood cells, maintaining healthy bone structure and protecting the central nervous system.

Vitamin B12 deficiency is less prevalent in the US and the UK (around 6%) but more prevalent in developing countries, with around 70% in Africa, 60% in Latin America. India is also not far behind, with around 75% prevalence of vitamin B12 deficiency. This can also be attributed to the fact that most Indians are vegetarian and do not get an adequate nutritional supply of Vitamin B12, which is rich in non-vegetarian foods.


The recommended dietary allowance for various age groups is given below (in micrograms):

  • Age up to 6 months: 0.4 mcg
  • 7-12 months: 0.5 mcg
  • 1-3 years: 0.9 mcg
  • 4-8 years: 1.2 mcg
  • 9-13 years: 1.8 mcg
  • Teenage 14-18 years: 2.4 mcg
  • Adults: 2.4 mcg
  • Pregnant women: 2.6 mcg per day (2.8 mcg per day if breastfeeding)


Signs and Symptoms

  • Anemia (especially pernicious anemia, where B12 can’t be absorbed because the intrinsic factor is not made by the stomach) 
  • Pale skin
  • Jaundice
  • Constant fatigue and weakness
  • Nerve damage
  • Losing balance and coordination while movement
  • Easy bleeding
  • Mouth ulcers
  • Dizziness and nausea
  • Breathing difficulties
  • Blurred vision
  • Mood swings
  • High temperature or fever (but very rare)



  • Blood tests to detect Vitamin B12 levels
  • Methylmalonic acid levels are also measured instead of B12, as its blood levels are very high in a B12 deficient person. Hence, it is considered a better indicator than B12 itself.
  • In the case of nervous system damage, the cerebrospinal fluid can also be tested for vitamin B12. However, since it is invasive, it is only preferred when blood tests give an unclear diagnosis.



  • Intake of Vitamin B12 dietary supplements. These come in the form of oral pills or injections.
  • Consumption of food rich in Vitamin B12 such as organ meats, shellfish, eggs, poultry, meat, milk and milk products, etc. A vegetarian diet usually lacks vitamin B12 but other alternatives could be fruits and vegetables, beans and lentils fortified with B12.
  • Taking multivitamins. It is well known that absorption of B12 is even better when taken with other vitamins of the B class such as B6, B3, B2, etc. These are available as one multivitamin tablet.