Tuesday, December 04, 2007

The Basics of Vitamin B-12

Vitamin B-12 is one of the B-Complex vitamins and is also known as Cobalamin. It is important for the normal functioning of the brain, nervous system and for the formation of red blood cells. Vitamin B-12 helps keep the red blood cells healthy which helps prevent heart disease and helps keep the immune system functioning at its maximum level. It is involved in the metabolism of every cell of the body, especially affecting the DNA synthesis and regulation.

Vitamin B-12 is also essential in fatty acid synthesis and energy production or the process that converts the carbohydrates, fats and proteins from food into energy. This vitamin is also important in maintaining the nervous system. All nerves are surrounded by a fatty protective covering made up of a complex protein called myelin.

If a deficiency occurs, DNA production is disrupted and abnormal cells are produced. This results in anaemia. Symptoms of anaemia include excessive tiredness, breathlessness, listlessness, pallor, and poor resistance to infection. Other symptoms might include a smooth, sore tongue and menstrual disorders. Prolonged deficiency can lead to nerve degeneration and irreversible neurological damage.

When a deficiency occurs, it’s most commonly linked to a failure to effectively absorb the vitamin from the intestine rather than a dietary deficiency. Vitamin B-12 is bound to the protein in food. Hydrochloric acid in the stomach releases Vitamin B-12 from proteins in foods during digestion.

Absorption of Vitamin B-12 requires the secretion from the cells lining the stomach of a glycoprotein, known as intrinsic factor. The intrinsic factor complex is then absorbed in the small intestine in the presence of calcium. Certain people are unable to produce intrinsic factor and the subsequent anaemia is treated with injections of Vitamin B-12.

The old Recommended Daily Amounts (RDA’s) have been replaced by the term Reference Nutrient intake (RNI). The RNI is the amount of nutrient which is enough for at least 97% of the population.

Reference Nutrient Intakes for Vitamin B-12, micrograms/day by age.

- 0 to 6 months 0.3 micrograms
- 7 to 12 months 0.4 micrograms
- 1 to 3 yrs 0.5 micrograms
- 4 to 6 yrs 0.8 micrograms
- 7 to 10 yrs 1.0 micrograms
- 11 to 14 yrs 1.2 micrograms
- 15 + yrs 1.5 micrograms
- Breast feeding women 2.0 micrograms

The vitamin has very low toxicity and exceeding the RNI is not considered to be dangerous.

The only verified unfortified sources of Vitamin B-12 are meat, dairy products and eggs. There has been plenty of research into possible plant food sources like soya products, seaweeds and algae, but analysis found no significant Vitamin B-12.

Strict vegetarians or vegans are likely to require supplements if they do not eat any animal products. Some sources of Vitamin B-12 for vegetarians are dairy products, free-range eggs, milk, vegetarian cheddar cheese, hard boiled eggs. Many vegan foods are actually supplemented with Vitamin B-12. These include yeast extracts, Vecon vegetable stock, veggieburger mixes, textured vegetable protein, soya milks, vegetable and sunflower margarines, and breakfast cereals.


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