Ever wondered how this Vitamin came into being or how was it discovered? By accident. Yes, you read it right. Deficiency of Vitamin B12 is actually the cause of pernicious anaemia, a disease that might prove fatal and had unknown aetiology when it was first described in medicine. Discovery of this Vitamin came in handy with the experiments being done to find the cure for this disease. George Whipple carried out experiments in which he induced anaemia in dogs by bleeding them and fed them with different foods to see what allowed the fastest recovery from the induced anaemia. He found out that large amounts of liver served the purpose of curing the disease faster than anything else leading him to give a hypothesis that liver might treat pernicious anaemia. This happened around 1920.
Now the substance that actually cured anaemia in dogs had to be isolated from liver. George Richards Minot and William Murphy took charge and found that it was iron. Eventually, they found out an entirely different liver substance capable of curing pernicious anaemia in humans, with no such effect on dogs. These experiments were reported around 1926 followed by preparation of liver extract. All these events led to the discovery of the soluble vitamin, called vitamin B12, from bacterial broths.
Also known as Cobalamin, it’s a water-soluble vitamin that has a vital role to play in the healthy functioning of the brain and nervous system and formation of red blood cells. No fungi, plants or animals are capable of producing it as they lack the enzymes needed for its synthesis. Only bacteria and archaea have the necessary enzymes. This one of the eight B vitamins is involved in the metabolism of every cell of the human body, especially affecting DNA synthesis, fatty acid and amino acid metabolism.
CHEMISTRY BEHIND VITAMIN B12
B12 is the largest and most structurally complicated vitamin. The uniqueness of this Vitamin is marked by the presence of the metallic ion, Cobalt, positioned in the centre of a planar tetrapyrrole ring called a corrin ring. It consists of Vitamers that show pharmacological activity and are produced by bacteria as hydroxocobalamin. The synthetic form is known as cyanocobalamin, produced by modifying the already mentioned hydroxocobalamin. This form is readily used in many pharmaceuticals and supplements due to its extra stability and low cost. In the body, it is converted into the human physiological forms methylcobalamin and 5’-deoxyadenosyl cobalamin. In this process, a cyanide ion (CN−) is produced, but the amount is very small compared to what would cause a toxicity risk. Cyanide-free synthetic forms of the vitamin—hydroxocobalamin, methylcobalamin, and adenosylcobalamin—are being used in some pharmacological products and supplements, but their claimed superiority to cyanocobalamin is debatable.
SOURCES OF VITAMIN B12
As neither plants nor animals are capable of producing this complex vitamin, we somehow, directly or indirectly obtain it from bacteria. Herbivores such as cows are said to obtain it from bacteria in their rumens by bacterial fermentation of food before it moves down to the intestine while some ferment in the large intestine and then consume these faeces. It is also found in fish and shellfish, meat, poultry, eggs, milk, and milk products. Non-animal sources include Chlorella, a fresh-water single-cell green alga, Spirulina and dried Asakusa-nori. Also, plants pulled from the ground and not washed may contain remnants of B12 from the bacteria present in the surrounding soil.
MEDICAL USES OF VITAMIN B12
It is used in the treatment of :
Vitamin B12 Deficiency – Symptoms include a decreased ability to think and personality changes like depression and irritability, abnormal sensations, changes in reflexes, inflammation of the tongue, decreased taste, low red blood cells, reduced heart function and decreased fertility.
Cyanide Poisoning – It occurs when a living organism is exposed to a compound that produces cyanide ions (CN−) when dissolved in water. For its treatment a large amount of hydroxocobalamin in infused directly into the vein, sometimes along with sodium thiosulfate.
DEFICIENCY OF VITAMIN B12
Its deficiency directly affects the brain and the nervous system and can even cause serious neurological damage in some cases. It comes with symptoms like fatigue, depression and poor memory, also mania and psychosis. Vegetarians are more likely to suffer from its deficiency as vegetables are a poor source of this vitamin. It can also be caused due to malabsorption, certain intestinal disorders, low presence of binding proteins, and use of certain medications.