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Vitamin B12 (Cobalamin)
This water soluble vitamin was isolated from liver extract in 1948 and was identified as the food factor that prevents the fatal condition pernicious anaemia. It contains the mineral cobalt, hence its name. It's required in tiny amounts by the body, but is essential for the functioning of all cells and is principally involved in energy metabolism and immune and nerve functions. Together with folic acid, the vitamin forms red blood cells to prevent anaemia, and promotes growth and appetite in children, increases energy, improves brain functions such as memory and learning ability, maintains a healthy nervous system, stabilises menstruation and prevents post-natal depression.
The absorption of B12 depends on a stomach secretion called the 'intrinsic factor'. Many people with reduced secretion suffer unknowingly from a deficiency of the vitamin, which can take years to manifest since B12 is stored in the liver - unlike the other water-soluble vitamins.
Deficiency of this vitamin is especially common in the elderly, and affects the brain and nervous system.
B12 is found in significant quantities only in animal products, and its richest sources are cheese, eggs, fish, liver, kidneys and sardines. In non-animal foods, B12 is found in fermented soya products (miso, tempeh, tofu), algae (blue-green algae, chlorella, spirulina) and bee pollen. Vegans and strict vegetarians also develop deficiencies and are advised to take supplements. The Recommended Daily Allowance is 2mcg for adults and 1mcg for children, but these are considered meagre by modern nutritionists - most supplements are available in potencies of between 60mcg and 2,000mcg. See 'Vitamin', 'Vitamin B Complex', 'Vitamin B2', 'VitaminB5', 'Vitamin B6', 'VitaminB15', 'Vitamin C', 'Vitamin D', 'Vitamin E', 'Vitamin K', 'Vitamin P'