Commonly known as the "anti-stress" vitamin, vitamin B12 is an affiliate of the vitamin B-complex group. As cobalt is one of the complex vitamins constituents, a scientific synonym for this water-soluble mineral is cobalamin.

The pivotal function of vitamin B12 is to aid in the formation of red blood cells in the human body. It is also vital for DNA replication during cell division. Vitamin B12 is an important quotient for maintaining the neurological health balance and the synthesis of myelin (a complex protein, constituting the sheath protecting nerve fibers) in particular with relation to the metabolism of fatty acids. It also enhances the activity of the immune system and the body's ability to withstand stressful conditions.

The authentic sources of vitamin B12 are animal foods. Meat, dairy products, and eggs contain this vitamin in substantial amounts. A possible plant source of vitamin B12 has been the subject of ongoing research. However, the prominent line of thought is that traces of vitamin B12 present in plant foods is highly variable in terms of content and cannot be relied upon as safe sources.

Vitamin B12 is an extraordinary vitamin. In comparison with other vitamins, the human body requires only a small ingestion of it. The Reference Nutrient intake (RNI) as per US standards is 4.5 mcg per day for young adult men, and 3 mcg/day for young adult women. Adults above 50 are prescribed to substantiate their diets with a greater quantity of about 10 to 25 mcg per day.

The liver is the main site for storage of vitamin B12 in the human body. It accounts for 80% of the reserves out of the 2.5mg average body stock of vitamin B12. Body reserves of vitamin B12 are directly proportional to the consumption levels. Vitamin B12 is also associated with the phenomenon of enterohepatic circulation, i.e., it is excreted in the bile and is effectively reabsorbed. It is because of the twin factors of body storage and re-absorption that it takes a considerable span time for a normal person to develop a deficiency syndrome.

Another unique feature is that vitamin B12 does not rely on whole food or plant-based diet as its source. Herbivores absorb this essential from the bacteria present in the digestive system. Vitamin B12 is generally stable, but prolonged cooking can destroy its food value by a considerable degree (estimated reduction of food value is by 1/3).

The most specific test for B12 status is methylmalonic acid (MMA) testing. The amount of vitamin B12 that comes out in the urine is measured by the Schilling test.

Vitamin B12 has a very low potential for toxicity, and, hence, there is no prescribed Tolerable Upper Intake Level for cobalamin. Medical experts are of opinion that its best to rely on food sources for the intake of vitamin B12.

Although required in small quantities, vitamin B12 acts as a catalyst to numerous body processes and as such is vital ingredient for the human body.