Q: What is the significance of vitamin B12 for human beings? If a person who is absolutely vegetarian and has deficiency of it, how can it be improved? A person who has very low vitamin B12, but there is no significant change in his blood profile (blood corpuscles, haemoglobin, etc.); how can this be normalised?

A:Vitamin B12 or cyanocobalamin is a water soluble vitamin necessary for the development of normal blood cells and neurologic tissue (brain, spinal cord and nerves). It cannot be synthesised by humans and the dietary sources are meat, eggs and dairy products. Even though bacteria present in our large intestine synthesise it, this cannot be absorbed and we have to rely on dietary sources for it. Its deficiency leads to anaemia (called megaloblastic anaemia) and various types of neurologic disorders, which are often irreversible. Boiling of milk or fermenting it to make yoghurt destroys most of the vitamin B12. Most of the vitamin B12 is stored in the liver and the daily requirement is about 2 micrograms. The body stores last for many years (2-5) even if the body is unable to absorb any dietary B12. Its deficiency can be caused by a) Reduced dietary intake – strict vegetarianism, alcoholism, dietary fads, b) Impaired absorption – intestinal disease, pernicious anaemia, parasite infestation, medications or c) Faulty utilisation (congenital enzyme deficiencies). Vitamin supplementation is the only means of appropriate vitamin B12 intake in people who choose to be on strict vegetarian diets.