Abstract: Vitamin-B12 is a vital vitamin for human health because the deficiency of this vitamin leads to the conditions like anaemia, various neurological disorders such as numbness, pins and needles sensations, a burning feeling in the feet, shaking, muscle fatigue, sleep disorders, memory loss, irrational anger, impaired mental function and Alzheimer’s. Besides these effects its deficiency also exerts some psychological conditions such as dementia, depression, psychosis and obsessive-compulsive behaviour. To overcome these problems daily intake of animal based food is recommended. In case of its deficiency signs some additional or supportive drugs containing vitamin-B12 either in form of pills and in emergency cases injections may be taken.