Vitamin B12 - Definciency or Pernicious anemia
Vitamin B12 is essential for the production of red blood cells in the bone marrow, neurological function, and DNA synthesis. Vitamin B12 can only be absorbed with the aid of an enzyme known as the intrinsic factor, normally produced by glands in the stomach.
Pernicious anaemia is an autoimmune disease that affects the stomach lining. This leads to failure to produce intrinsic factor, resulting in vitamin B12 mal-absorption. If pernicious anaemia is left untreated, it causes vitamin B12 deficiency, leading to megaloblastic anaemia and neurological disorders, even in the presence of adequate dietary intake of vitamin B12.
The main causes of vitamin B12 deficiency include
- mal-absorption from food
- pernicious anaemia
- postsurgical mal-absorption
- and dietary deficiency
Vitamin B12 is found in foods that come from animals, including fish and shellfish, meat (especially liver), poultry, eggs, milk, and milk products.
Who is at risk?
- People taking anti-acids regularly may cause mal-absorption of vitamin B12, as some anti-acids reduce the production of the intrinsic factor.
- People with atrophic gastritis are unable to absorb vitamin B12 that is naturally present in food. Most, however, can absorb the synthetic vitamin B12 added to fortified foods and dietary supplements.
- People with pernicious anaemia.
- People with stomach and small intestine disorders, such as celiac disease and Crohn's disease, may be unable to absorb enough vitamin B12 from food to maintain healthy body stores.
- Surgical procedures in the gastrointestinal tract, such as weight loss surgery or surgery to remove all or part of the stomach, often result in a loss of cells that secrete hydrochloric acid and intrinsic factor.
- Strict vegetarians and vegans are at risk because natural food sources of vitamin B12 are limited to foods from animals.
What are the symptoms of vitamin B12 deficiency?
Symptoms may be very mild, but can include
- Diarrhea or constipation
- Fatigue, lack of energy, or light-headedness when standing up or with exertion
- Loss of appetite
- Problems concentrating
- Shortness of breath, mostly during exercise
- Swollen, red tongue or bleeding gums
The neurological symptoms of vitamin B12 deficiency can occur without anaemia, so early diagnosis and intervention is important to avoid irreversible damage. Symptoms from nerve damage caused by vitamin B12 deficiency that has been present for a longer time include:
- Confusion or change in mental status (dementia) in severe cases
- Loss of balance
- Numbness and tingling of hands and feet
Folic acid and vitamin B12
Large amounts of folic acid can mask the damaging effects of vitamin B12 deficiency by correcting the anaemia caused by vitamin B12 deficiency without correcting the neurological damage that also occurs.
Moreover, preliminary evidence suggests that high serum foliate levels might not only mask vitamin B12 deficiency, but could also aggravates the anaemia and worsen the cognitive symptoms associated with vitamin B12 deficiency. Permanent nerve damage can occur if vitamin B12 deficiency is not treated.
For these reasons, folic acid intake from fortified food and supplements should not exceed 1,000 mcg daily in healthy adults.
If you suspect that you may be deficient in vitamin B12, see your doctor who will run blood test
For more researched information on vitamin B12 go to
The Office of Dietary Supplements
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