Vitamin B12 is also called cobalamin, a water-soluble vitamin that is derived from our food (mostly animal products such as red meat, eggs, dairy, etc.) and absorbed by the gut and stored in the liver. 

However, if the absorption and storage are hindered either due to dietary insufficiency, malabsorption syndrome or intrinsic factor deficiency, the liver stores are depleted, leading to B12 deficiency and its associated symptoms.

Role of Vitamin B12

Vitamin B12 plays a vital role in the functioning and development of the central nervous system (brain and spinal cord), red cell formation, DNA (deoxyribonucleic acid that makes up the genetic material) synthesis, amino acid (building blocks of life) and fatty acid synthesis, etc.

Symptoms of Vitamin B12 Deficiency 

The symptoms are often not very specific, so vitamin B12 deficiency can go unnoticed for a long period of time. It is also easily mistaken for other conditions and therefore remains underdiagnosed. 

This is where the danger lies. By the time it is diagnosed, most often, some amount of irreversible damage has already occurred which is why it is imperative that you are aware of the signs and symptoms of this condition.  

The Five Alarming Signs of B12 Deficiency 

1. Dizziness or Light-headedness

Impaired balance, lack of coordination, difficulty in walking are all the neurological symptoms of vitamin B12 deficiency. As it is a potent brain compound, its deficiency would naturally affect the healthy functioning of our central nervous system. 

Two main organs in relation to the brain responsible for maintaining balance are the eyes and ears. Sometimes, the optic nerve (nerve innervating the eyes) can also be damaged due to severe deficiency leading to visual disturbances and balance issues.

2. Lack of Concentration And Mental Impairment

Chronic and uncharacteristic forgetfulness may indicate a B12 deficiency. Many patients assume that they are suffering from dementia or Alzheimer’s, especially in their senior years while all they lack is the B12 vitamin. 

Fortunately, a  simple blood test can diagnose B12 deficiency, and a supplemental regimen can help improve your symptoms (such as lack of focus, poor memory, forgetfulness, etc) significantly.

3. Generalized Fatigue

Insufficient vitamin B12 (or folate) deficiency, in particular, causes megaloblastic anaemia wherein the red cells are large, immature with impaired DNA synthesis. This qualitative defect of red cells results in insufficient oxygenation of the body's cells, leading to chronic weakness or tiredness and muscle weakness. 

It can also negatively impact the sensory and motor nerve functions causing painful muscle cramps. 

4. Pale Complexion or Yellow Skin

Those suffering from B12 deficiency are pale in their complexion due to the lack of red blood cells. This lack of red cells could be due to decreased red cell production or an increase in red cell destruction. 

In the case of the latter, when red cells are destroyed they release a pigment called bilirubin which is the reason behind that yellow skin. It can also cause your liver or spleen to swell up.

5. Pins and Needles Sensation in Your Hands And Feet

Paresthesia is a medical term given to what patients refer to as pins and needle sensation in their limbs (hands and feet). 

Unfortunately, it's often under or misdiagnosed as this symptom can be overlapping with that of diabetic neuropathy (where the high blood sugars damage the nerve and cause pain and numbness in the extremities).

When in doubt, it is always recommended to seek medical help and get regular screening done, especially if you are a diabetic and are on metformin treatment as the drug is known to cause B12 deficiency.

In addition to the above-mentioned symptoms, B12 deficiency can also lead to the following:  

  • Headache

  • Gastrointestinal issues such as bloating, nausea, diarrhoea, etc

  • Inflammation of the tongue (glossitis) and perioral region (stomatitis).

  • Ringing in the ears (tinnitus).

  • Difficulty in breathing and palpitations (increased heart rate).

  • Difficulty sleeping (insomnia).

  • Erectile dysfunction.

Note: In addition to knowing your symptoms, getting a regular physical exam and blood tests (that include CBC with peripheral smear, B12, folate, MMA and homocysteine levels) can help in early diagnosis and effective management of the condition.


B12 deficiency can manifest with an array of symptoms from headaches to constipation. Most of these symptoms are not very specific to B12 deficiency, which is why it is hard to catch the condition early and treat it.

Just don’t forget to ask your doctor regarding the oral supplements or injections and also make sure to increase your intake of B12-rich foods (eggs, yoghurt, cheese, beef chicken, etc.) so as to meet your daily requirements. 

Disclaimer: This article is written by the Practitioner for informational and educational purposes only. The content presented on this page should not be considered as a substitute for medical expertise. Please "DO NOT SELF-MEDICATE" and seek professional help regarding any health conditions or concerns. Practo will not be responsible for any act or omission arising from the interpretation of the content present on this page.