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Vitamin B12 deficiency and symptoms

Introduction Vitamin B12

A balanced diet contains all macro and micronutrients required for the normal functioning of a human body. Vitamin B12, also called cobalamin, is one of the most vital substances for humans. However, there are still many people suffering from Vitamin B 12 deficiency due to a strict vegan food diet or if you are older and lost your ability to absorb it efficiently. It leads to many bothersome symptoms. In this article we will tell you more on what Vitamin B12 is, why you need it and how you can test your Vitamin B12 level. 

What is Vitamin B12?

Vitamin B12 is a type of vitamin B which is crucial for normal functioning of the human body. It is a water-soluble vitamin which is naturally present in many food items. Animal sources include liver, fish meat, red meat, egg, poultry and milk. Plant sources are limited and some seaweeds and algae contain it.

Vitamin B12 is required for normal production of different body cells like:

  • Red blood cells and DNA
  • Brain cells

It is essentially required for normal production of every cell of the human body because of its role as a cofactor of the involved enzymes in DNA synthesis. Other than that, it takes part in amino acid metabolism and fatty acid metabolism that go on in the body all day long. So, the importance of vitamin B12 cannot be stressed enough.

There are large stores of vitamin B12 in the body and deficiency only occurs when these stores are depleted that happens over the years. Vitamin B12 deficiency is when it is below 200 pg/mL in your blood. The deficiency is widespread but its prevalence varies in different countries. Also, it is different in different age groups. It is more common in elderly population, i.e. 60 years or older, in all parts of the world. However, it can affect any age group (1).

Following are the different situations where vitamin B12 deficiency may occur.

  • In vegetarians because such diet is deficient in vitamin B12
  • In the elderly due to malabsorption
  • In neonates and infants who are breastfed by vegetarian mothers
  • In chronic gastrointestinal disorders like Crohn’s disease
  • In chronic alcoholism due to disruption of its absorption
  • Due to some medications like proton pump inhibitors (PPI) and metformin

So the major causes of vitamin B12 deficiency are malabsorption and inadequate diet (2).

As vitamin B12 is involved in cell metabolism of the human body, its deficiency can be dangerous. It can cause pernicious anemia, neuropsychiatric symptoms and elevated serum homocysteine levels (3). Also, the deficiency occurs silently over the years so, it goes unnoticed and is detected only when symptoms are observed.

Symptoms of Vitamin B12 Deficiency

It can take years for the symptoms to show up because of the large stores of vitamin B12 present in a human body. Following are the symptoms of its deficiency (4).

  • Neurological problems like pins and needles sensations and muscle weakness as it is necessary for normal neurological cell production and deficiency leads to impairment of the nervous system
  • Visual impairment like blurred vision or loss of vision as a result of damage to the optic nerve
  • Psychological symptoms like depression, changed behavior and memory issues caused by impaired functioning of the nervous system
  • Pale skin due to jaundice caused by impaired red blood cells metabolism
  • Fatigue caused by decreased oxygen delivery to body cells because of decreased production of the red blood cells
  • Breathlessness and palpitations as a result of body’s mechanisms to combat decreased oxygen levels due to anemia
  • Frequent oral ulcers due to the deficiency
  • Flat and inflamed tongue that looks red and swollen
  • GIT disturbances like diarrhea, constipation and flatulence can also be experienced

Fever is also a rare symptom

Vitamin B12 Overdose

Vitamin B12 overdose is a rare phenomenon. It is water-soluble vitamin which is not toxic. When a person takes vitamin B12 in excess, it is excreted through the kidneys.

Pernicious anemia is often treated by giving heavy doses of vitamin B12 and no toxicity or side effects have been noticed yet (5). So, large amount of vitamin B12 are safe in a healthy person as it gets excreted without being excessively accumulated in the body.

Though its toxicity has not been reported but some allergies and drug interactions can be noticed. A case was reported where anaphylactic reaction ensued after an injection of vitamin B12 (6).

Vitamin B12 has been reported to cause drug interaction with antiepileptic drugs like carbamazepine, gabapentin, oxcarbazepine etc. that are used to treat epilepsy and other psychiatry disorders (7).

However, vitamin B12 is a very safe vitamin and can be given in large quantities to a healthy individual in order to treat diseases like pernicious anemia and to fulfill nutritional deficiencies.

How to Get Vitamin B12 from your Diet

A healthy and balanced diet is the one that provides you with all important nutrients, including macro and micronutrients. Appropriate dietary sources can easily fulfill the daily requirement of vitamin B12 and prevent deficiencies. Incorporating vitamin B12 rich dietary sources in your diet is the best option. Following are different dietary items that are rich in vitamin B12 (8):

  • Tuna and other fishes are a rich source of vitamin B12 and only a few ounces fulfill your daily requirement of it
  • Other seafood items like shrimps, oysters, clams, mussels etc. are also equally good
  • Cheese is a good source
  • Milk and other dairy products are an important source and a cup of milk can almost provide you with a whole day’s vitamin B12
  • Red meat like beef and lamb should be a part of diet
  • Chicken is also a good source
  • Egg, in any form, is a great source of vitamin B12 and it is cheap as well
  • Nutritional yeast or nooch is a good option for vegetarians and it is quite rich in vitamin B12
  • Beef liver is a great source
  • Fortified cereals taken in the breakfast are a very good option

Add a portion of any of vitamin B12 rich foods in your daily diet to prevent its deficiency and live a healthy lifestyle.

Home health test kits to for analyzing and testing your Vitamin B12 level

Vitamin B12 home test

Vitamin B12 (Active)


Comes with a finger prick blood test sample collection kit and you can take a sample at home. Send the sample to laboratory by postage the following day. It will be analyzed by the laboratory and result will be emailed.


  • Can be done in the comfort of your home
  • Easy sample collection


  • Not available worldwide

Vitamin B12 home test

Vitamin B12 Blood Test


Order a test online. Visit the laboratory for sample collection and get the result online.


  • Cheap
  • Online results


  • Turnaround time of up to 10 days
  • Laboratory visit required

Vitamin B12 home test

Vitamin B-12 Blood Test

True Health

Order a test online. You will receive a kit. Go to the nearest collection center for sample collection and receive the result online.


  • Online results
  • Good turnaround time


  • Expensive
  • Not available worldwide

Vitamin B12 home test

Vitamin B12 Test


Comes with a finger prick blood test sample collection kit and you can take a sample at home. Send the sample to laboratory by postage the following day. It will be analyzed by the laboratory and result will be emailed.


  • Can be done in the comfort of your home
  • Easy sample collection


  • Not available worldwide