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Vitamin B12 deficiency

Vitamin B12 is part of the B-vitamin complex. When a person does not have sufficient amounts of it in his body, then there is a vitamin B12 deficiency. It can be caused by several reasons, and may lead to a variety of symptoms, some of which are mentioned on this page.


When a person is deficient in this vitamin, some symptoms can appear. Certain ones are listed below. Please keep in mind that this list is not exhaustive. Also, as other reasons can cause these to occur, having these particular signs does not necessarily mean that someone has a vitamin B12 deficiency.

Ataxia (involving the dorsal nerve cord)
Gastrointestinal signs
Impaired memory
Megaloblastic anemia
Various neurological symptoms

It is considered that those signs brought on by a lack proper amounts of this vitamin can be reversed when levels of it are brought back to normal. However, if they are due to a different cause then they may not improve despite raised levels of B12.


Various reasons can lead to a vitamin B12 deficiency. One possibility is an insufficient dietary intake of it. This is somewhat rare, however it can occur in a vegan diet. Children are more susceptible to developing the condition this way. It is possible for malabsorption to occur, either in due to intrinsic factor deficiency, or of a more general nature. Some types of achlorhydria can also lead to malabsorption of this vitamin. Celiac disease is an example of a medical condition that can also worsen absorption.

Related condition

A similar issue which can occur is a vitamin B5 deficiency. This may also lead to paresthesia in the individual.

Read more about paresthesia, or go straight to the list of other possible medical causes.