Vitamin B12

Vitamin B12 belongs to the Vitamin-B group. Structurally, vitamin B12 is the largest among all other vitamins (B1, B2, B3, B5, B6, B7 and B9) of the same group. Vitamin B12 is also known as Cobalamin, as it contains the mineral cobalt.

Methylcobalamin and 5′ deoxyadenosylcobalamin are the two metabolically active forms of cobalamin. Bacteria and archaea secrete vitamin B12. It performs a significant role in maintaining brain health, proper functioning of the nervous system, and synthesis of RBCs.

In this post, we will discuss the definition, food sources and functions of vitamin B12. In addition, deficiency symptoms, dosages, side effects and uses of vitamin B12.

Content: Vitamin B12

  1. Definition
  2. Food Sources
  3. Functions
  4. Vitamin B12 Deficiency
  5. Dosages
  6. Side Effects
  7. Uses

Definition of Vitamin B12

Like all other vitamins of the B complex, Vitamin B12 is also water-soluble. So, once we intake food incorporated with vitamin B-12, it binds with heaptocorrin in the saliva. Then, the whole complex goes to the stomach, where the digestive enzymes free the vitamin B12 from haptocorrin.

Finally, the ileum or distal portion of the small intestine absorbs vitamin B12. A human body reserves useful vitamin B12 for up to 4 years in the liver and excretes the unused vitamin B12 products through urine.

Industrially, it is produced only through bacterial fermentation. The table below mentions the specific properties of vitamin B12.

Properties Vitamin B12
Alternative / Common nameCobalamin
Chemical formulaC63H88CoN14O14P
ColourDark red crystals or an amorphous or crystalline red powder
SensitivityLight sensitive
Sources of CobalaminMutton, fish, shellfish, fortified cereals, chicken, cheese, milk etc.

Vitamin B12 Foods

People above the age of 14 years need to take a minimum of 2.4 micrograms of vitamin B-12 daily. Non-vegetarians get the daily requirement of cobalmin through different animal sources, whereas vegetarians get vitamin B-12 through fortified cereals, fruits or some dietary supplements.

Sources of vitamin B12

Naturally, vitamin B-12 is available in the form of the following food sources:

  • Animal sources like eggs, beef liver, ham, chicken breast, clams, trout and tuna.
  • Plant-based non-dairy products like tofu, soy, almond, cashew, rice and coconut milk.
  • Dairy products like milk, yoghurt and cheddar cheese.
  • Fruits like banana, papayas and strawberries.
  • Fortified cereals, oatmeal and legumes.

Dietary Supplement: Cobalamin can also be produced industrially through the fermentation process using some particular microbial strains.

In 1972, Robert Burns Woodward and Albert Eschenmoser established a complete synthetic laboratory to synthesise vitamin B-12. However, it did not give good potential because by completing 70 steps, only a 0.01% yield was achieved.

Functions of Cobalamin

The functions of Cobalamin includes:

  1. For the proper functioning of the brain and nervous system, vitamin B-12 plays a crucial role.
  2. Vitamin B-12 helps in forming red blood cells and also in creating and regulating the functioning of DNA.
  3. Cobalamin aids the synthesis of fatty acids and the production of cellular energy.
  4. Vitamin B-12 facilitates absorption of folic acid, due to which dissipation of energy takes place from the human body.
  5. Vitamin B-12 helps in the proper multiplication of erythrocytes. So, if the cobalamin level reduces, the production of RBC also reduces that eventually leads to anaemia.

Vitamin B12 Deficiency Symptoms

  1. The deficiency of vitamin B-12 causes potentially severe damage to the human brain and nervous system. It may also cause permanent damage to the brain and nervous system.
  2. Lack of vitamin B-12 is also related to the problems like weight loss, weak appetite and constipation.
  3. Psychosis, mania, and dementia are some of the major problems that also result from the scarcity of vitamin B-12.
  4. Its lack causes neurological changes, like the tingling of body parts and difficulty in balancing the body.
  5. Depression, memory problems, confusion and fatigue, are some of the significant health problems triggered due to the slight deficiency of vitamin B-12. However, these problems also may consequence due to other reasons.
  6. Infants also face various health issues like difficulty in feeding, skin irritation, face tremors etc.
  7. Vitamin B-12 causes anaemia. The various symptoms observed in anaemic patients are breath shortness, irregularity in heartbeat and fatigue. Also, it may cause weight loss, pale skin colour, problems in the menstrual cycle, diarrhoea and sores in the mouth.


As per the National Institutes of Health (NIH) in the US, teens and adults above 14 years need to intake 2.4 micrograms of vitamin B-12 per day. A pregnant lady needs to intake 2.6 micrograms, and lactating women need to take 2.8 micrograms per day.

However, excess intake of vitamin B-12 is not harmful, but still, people advised to consult a physician before taking the supplements. Some of the drugs metformin, proton pump inhibitors, and hydrogen receptor agonists may interfere with the working of vitamin B-12.

Side Effects

Generally, there are minimal side effects of taking vitamin B-12. Vitamin B-12 is not toxic even by taking 1000 micrograms per day. None of the cases has been reported since 2001 of an adverse situation raised due to vitamin B-12 supplement.

Cyanocobalamin is a form of supplement that contains cyanide, and it is injectable in nature. Because of the presence of cyanide, it is concerned that it may be poisonous. However, cyanocobalamin supplements are not recommended for kidney patients.

Uses of Vitamin B12

Vitamin B12 has diverse applicabilities like:

Preventing Loss of Brain Neurons

Loss of neurons present in the brain is termed brain atrophy, and it is associated with memory loss or dementia. Vitamin B-12 prevents the loss of brain neurons. Studies proved that early-stage dementia could be prevented by using a combination of vitamin B-12 with omega-3 fatty acid.

Gives Energy Boost to the Body

All vitamin B types are involved in the production of energy. Although, they themselves do not provide energy. If someone is deficient in vitamin B-12, then taking supplements or increasing vitamin B12 intake may increase strength. Vitamin B-12 deficiency causes fatigue and lack of energy.

Improves Heart Health

The risk of heart diseases increases with an increase in amino acid homocysteine in the blood. Elevation in homocysteine level makes a person deficit in vitamin B-12. Studies showed that vitamin B-12 reduces homocysteine level, which will reduce risks associated with heart disease.

Healthy Hair, Skin and Nails

Vitamin B-12 is necessary to fulfil the demand for adequate vitamin level in our body, as it promotes healthy hair, skin and nails. Deficiency of vitamin B-12 causes dermatology symptoms. In addition, it causes hyperpigmentation, discolouration of nails, hair colour changes, vitiligo and angular stomatitis.

Helps in RBC Formation and Anemia Prevention

The deficiency of vitamin B-12 reduces red blood cells count and also prevents its proper development. Red blood cells generally appear concave circular disks, but vitamin B-12 deficiency causes a change in its shape (oval or more substantial forms).

Due to these irregularities in shape and size, RBC cannot move correctly through bone marrow and leads to megaloblastic anaemia. Anaemia causes fatigue and weakness in the body.

Prevents Major Birth Defects

For the proper development of the fetus brain and nervous system, an adequate supply of vitamin B-12 is required from the mother. Deficiency in vitamin in pregnancy time may cause significant congenital disabilities like neural tube defects. Also, deficiency of vitamin B-12 in the mother may cause premature birth or miscarriage.

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