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Vitamin B12: Frequently Asked Questions

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By Apollo 24/7, Published on- 20 August 2021, Updated on - 28 October 2022

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Vitamins are micronutrients that are necessary for the proper development and functioning of the body. One such important vitamin is B12, which is extremely necessary for optimal nerve and brain health. Vitamin B12 is also called cobalamin as it contains traces of the mineral Cobalt. Let us address the frequently asked questions about this important nutrient. 

1. Why is vitamin B12 necessary for the body?

Vitamin B12 is required for the:

  • Synthesis of red blood cells and DNA (the genetic material in all the cells)
  • Production of energy in the body
  • Maintenance of nerves and brain function.

2. How much vitamin B12 is required regularly?

The recommended dietary allowance for vitamin B12 is 2.4 micrograms for adults (both men and women) and 0.4 to 2.4 micrograms for children. The need for vitamin B12 increases to 2.6 mcg during pregnancy and 2.8 mcg during lactation.

3. What are the food sources of vitamin B12?

Vitamin B12 is naturally found in several animal foods, which include:

  • Fishes such as herrings, salmon, sardines, tuna and trout
  • Red meat and organ meat such as liver 
  • Poultry and eggs
  • Dairy products such as milk, cheese and yoghurt
  • Fortified foods such as breakfast cereals, nutritional yeasts and enriched soy.

4. What are the signs of vitamin B12 deficiency?

Usually, the human body stores enough vitamin B12 in the body and hence, the symptoms of deficiency may not appear until it is severe. The common signs of vitamin B12 deficiency include:

  • Megaloblastic anaemia (the red blood cells become larger than normal and do not function properly)
  • Fatigue 
  • Pale skin
  • Heart palpitations
  • Frequent headaches 
  • Loss of appetite
  • Constipation 
  • Weight loss
  • Sore, inflamed tongue with mouth ulcers
  • Numbness or tingling sensation in the hands and feet (indicating nerve damage)
  • Vision problems
  • Difficulty in walking and maintaining balance 
  • Infertility
  • Confusion
  • Forgetfulness 
  • Dementia 
  • Infants show a delay in reaching developmental milestones and difficulty in moving. 

If a person develops any of the symptoms mentioned above, they must consult a doctor for further examination. Undiagnosed vitamin B12 deficiency can cause irreversible damage to the nerves and brain. 

5. Who is more likely to develop vitamin B12 deficiency?

Anyone can develop vitamin B12 deficiency but factors that may increase the risk include:

  • Vegetarianism: Plant-based foods do not contain vitamin B12. Therefore, strict vegetarians or vegans have a high risk of developing vitamin B12 deficiency. 
  • Stomach conditions: People with an autoimmune disease called atrophic gastritis might not absorb enough vitamin B12 because they make too little hydrochloric acid and intrinsic factors in their stomach.
  • Old age: As age progresses, the release of hydrochloric acid in the stomach reduces in some people. This prevents the absorption of vitamin B12 in the body, resulting in a deficiency.
  • Lack of intrinsic factor: Intrinsic factors are a type of protein released by the mucosal layer of the stomach, which facilitates the absorption of vitamin B12. People who lack intrinsic factors have difficulty absorbing vitamin B12 from foods and dietary supplements. 
  • Surgeries: People who have undergone gastric or intestinal surgeries may have trouble producing enough hydrochloric acid and intrinsic factors required to absorb vitamin B12.
  • Intestinal diseases: People suffering from intestinal disorders such as celiac disease or Crohn’s disease are more likely to develop vitamin B12 deficiency as they are unable to absorb enough vitamins in the body.

6. Who should consume vitamin B12 supplements?

Vitamin B12 supplements are generally recommended for people who do not get enough from their daily diet. Supplements are easily available over the counter either in combination with B-complex supplements or alone in the form of cyanocobalamin. However, it is not recommended to consume vitamin B12 supplements without consulting a doctor as they can interfere with some other medicines. These medicines include:

  • H2 blockers: Medicines such as omeprazole, lansoprazole, cimetidine, and ranitidine are gastric acid inhibitors that are used for the treatment of some digestion problems, such as gastroesophageal reflux disease and peptic ulcer disease. People who consume these medicines may experience difficulty in absorbing vitamin B12 as they reduce the release of hydrochloric acid into the stomach. 
  • Metformin: Metformin is a medicine used for the treatment of diabetes. Metformin can reduce the absorption of vitamin B12 while decreasing the levels of vitamin B12 in the blood.

7. Does excess vitamin B12 result in toxicity?

Vitamin B12 is a water-soluble vitamin, hence all the extra amount of unused vitamin gets released out of the body through the urine. Therefore, there are no adverse effects of excess vitamin B12 intake from food or supplements in overall healthy people. However, it is advised to consult a doctor before taking any high-dosage supplement.


Vitamin B12 is an essential nutrient that is required for the production of healthy blood and nerve cells. Strict vegetarians or those who have undergone intestinal or weight-loss surgery should get their vitamin B12 levels checked frequently as it can interfere with the absorption of the nutrient present in the food. Early detection and treatment of vitamin B12 deficiency can help prevent potential neurological and blood disorders.

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