Vitamin B12 Deficiency: Causes, Symptoms, and Treatment

Vitamin B12 is an important water soluble vitamin that has many crucial roles in the body. The roles of B12 include the production of healthy red blood cells in the blood, and it is found mostly in meat sources such as red meat and poultry, as well as in fish and dairy products. Here we will look at the problems caused by vitamin B12 deficiency, the factors that cause it and the symptoms.

Causes of Vitamin B12 Deficiency

A vitamin B12 deficiency can be simply the result of the body not getting enough protein through the diet. This is a rare and extreme problem, but is relatively common for vegetarians and particularly vegan vegetarians as there are no plant sources of vitamin B12. Meanwhile some conditions can make it impossible to absorb vitamin B12 efficiently in the diet – and these include atrophic gastritis, celiac disease, Crohn’s disease, pernicious anaemia and damage to the stomach or small intestine.


Initial symptoms of a vitamin B12 deficiency vary depending on the cause, the severity and other factors. Furthermore they are hard to diagnose as the symptoms can be mistaken for other causes of low red blood cells (such as low iron) and as they can be minor or vague.

However, common symptoms may include:

  • Numbness in the hands and feet
  • Tingling in the extremities
  • Constipation
  • Depression
  • Fatigue
  • Weakness
  • Tiredness
  • Shortness of breath
  • Sore mouth and tongue
  • Pale skin
  • Low appetite

Vitamin B12 deficiency can eventually result in severe nerve damage and dementia. It is highly important then to keep note of any such symptoms and to see a doctor if you suspect you are suffering these symptoms.


Treatment is relatively easy once the condition is properly diagnosed. Normally this will involve injections of vitamin B12 – which may need to be a life-long treatment in the scenario that your body is unable to absorb B12. Meanwhile oral B12 may be prescribed as a supplement, or you may just have to eat more meat and other natural sources. In the case that the malabsorption is caused by an underlying condition, this will need to be treated.

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