Vitamin B12

Vitamin B12

also called cobalamin.

is a water soluble vitamin.

is the largest vitamin molecule known.

is involved in the metabolism of every cell of the human body, affecting DNA synthesis and regulation, also essential for fatty acid and amino acid metabolism.

is required for the proper function and development of the brain, nerves, blood cells, and many other parts of the body.1

Bacteria and archaea have the enzymes required for vitamin B12 synthesis.

What are the causes of vitamin B12 deficiency?

Vitamin B12 deficiency may be due to 2

  1. Pernicious anemia, which makes it hard for your body to absorb vitamin B12.
  2. Surgery that removed part of the stomach or small intestine, including weight loss surgeries.
  3. Certain diseases such as Crohn's disease, Graves' disease, or lupus, and bacterial growth, or a parasite.
  4. Heavy drinking.
  5. Long-term use of Antacids decreases the absorptions of vitamin B12 leading to deficiency.
  6. Atrophic gastritis, in which your stomach lining has thinned.
  7. Vegetarians are more likely to develop vitamin B12 deficiency as their diet lacks rich sources of vitamin B12 such as animal products including meat, milk, cheese, and eggs.
  8. Babies born to mothers who are vegetarians may also not get enough vitamin B12.
What are the uses of Vitamin B12?
  1. Improvement of the pain perception for diabetic patients.

  2. Improvement of the cognitive functions in dementia and alzheimer.
  3. Correction of Megaloblastic and Pernicious Anemia.

  4. Optimization of the immune status.
  5. Enhancement of the physical activity.
  6. Improvement of the general well being.

What foods provide vitamin B12?3,4
Vitamin B12 is found in a variety of animal foods. Plant foods have no vitamin B12 unless they are fortified.

Natural sources of B12 include:

  1. Organ meats (beef liver)
  2. Shellfish (clams)
  3. Meat, poultry, eggs, milk and other dairy foods
  4. Fortified breakfast cereals and nutritional yeasts
Am I getting enough vitamin B12? 3
The amount of vitamin B12 you need each day depends on your age. Average daily recommended amounts for different ages are listed below in micrograms (mcg):
Life Stage Recommended Amount of Vitamin B12
Birth to 6 months 0.4 mcg
Infants 7–12 months 0.5 mcg
Children 1–3 years 0.9 mcg
Children 4–8 years 0.9 mcg
Children 9–13 years 1.8 mcg
Teens 14–18 years 2.4 mcg
Adults 2.4 mcg
Pregnant women 2.6 mcg
Breastfeeding women 2.8 mcg
What are the symptoms of Vitamin B12 deficiency?5

Symptoms develop slowly they include:

  1. Fatigue and muscle weakness
  2. Shortness of breath and dizziness
  3. Numbness
  4. Heart palpitations
  5. Bleeding gums and mouth sores
  6. Nausea, poor appetite and diarrhea
  7. Higher susceptibility to infections
  8. Menstrual problems
If the deficiency continues untreated the patient may have the following neurological signs and symptoms:
  1. Numbness and tingling in the hands and feet
  2. Difficulty walking (staggering)
  3. Muscle weakness
  4. Irritability
  5. Memory loss
  6. Dementia
  7. Depression
For infants, signs of vitamin B12 deficiency include:
  1. Failure to thrive
  2. Movement problems
  3. Developmental milestones delays
  4. Megaloblastic anemia


  1. Dietary Supplement Fact Sheet: Vitamin B12 — Health Professional Fact Sheet. 2015. Available at: Accessed January 1, 2015.

  2. Vitamin B12: MedlinePlus Medical Encyclopedia. 2015. Available at: Accessed March 1, 2015.

  3. vitamin b12: Uses, Side Effects, Interactions and Warnings - WebMD. 2015. Available at: Accessed March 25, 2015.
  4. Allen L. How common is vitamin B-12 deficiency?.American Journal of Clinical Nutrition. 2009;89(2):693S-696S. doi:10.3945/ajcn.2008.26947a.

  5. Vitamin B12 Deficiency: Causes, Symptoms, and Treatment. 2015. Available at: Accessed January 10, 2015.