Vitamin B12
Cobamamide, cyanocobalamine, dibencozide, hydroxocobalamine
Description
Every cell in the body requires vitamin B12. It is necessary for the formation of haemoglobin (red blood cells) and DNA, it participates in the production of amino acids and is also involved in the maintenance of myelin throughout the nervous system.
Vitamin B12 requires the intrinsic factor and adequate levels of stomach acid and pepsin (digestive enzyme) for proper absorption. If one of these factors is lacking, absorption is compromised.
Sources
Giblets, seafood, fish, meat, eggs, dairy products, fortified cereals and fortified soy products are among the richest sources of vitamin B12. It is important for strict vegetarians to eat fortified food products since there is no vitamin B12 in vegetables.
Vitamin B12, found in fortified products such as cereal, is more readily absorbed since it is not bound to food. It only needs the intrinsic factor to be absorbed.
Approximate Vitamin B12 Content | ||||||||||||||||||||||||||||||||||||||||
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Vitamin B12 is stable when cooked.
Recommended Daily Allowance (RDA)
Recommended average daily nutrient intake that is sufficient to meet the nutrient requirements of nearly all (97 to 98%) healthy individuals in each age and gender group. The RDA should only be used as a guide for daily individual intake.
Vitamin B12 Requirements | |||||||||||||||||||||||||||||||
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The average American diet consists of 5 to 15 mcg of cyanocobalamine.
Deficiency
Anemia and irreversible neurological damage are caused by a vitamin B12 deficiency.
Symptoms include loss of appetite, constipation, depression, confusion, memory loss, taste alteration, weakness, fatigue, sensory disturbances, weight loss and symptoms of heart failure.
Deficiency is caused by:
- Inadequate dietary intake of foods that are rich in vitamin B12. Vegetarians who do not eat animal products are at risk and should be aware of this increased risk.
- Impaired absorption. Those 50 years and older who drink large quantities of alcohol or take medications that reduce stomach acid have an increased risk.
Since there is 5 to 7 years worth of vitamin B12 stored in the liver, it could take several years for deficiency-related problems to appear. Furthermore, folic acid supplements can mask symptoms of anemia, which can delay the appearance of symptoms and therefore increase the risk of neurological problems.
Toxicity
No cases of vitamin B12 toxicity have been reported.
Supplements
A moderate intake of foods that are rich in vitamin B12 is enough to prevent any deficiency. It is suggested however, that those 60 years and older take a multivitamin that contains 6 mcg of vitamin B12.
Supplements are also advised for vegetarians. This is particularly important for women who are nursing, since the baby could also be deficient.
In the event of a vitamin B12 deficiency, intramuscular injections are usually given to remedy the deficiency. Then, a maintenance treatment, in the form of monthly injections or oral supplements of 1000 mcg per day can be initiated. Medical monitoring is important.
Watch what you eat. Nutrition has a significant impact on health!
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