Anaemia is not a disease. It is a symptom of various diseases which may result from excessive blood loss, excessive blood cell destruction, or decreased blood cell formation. Folic acid is a part of coenzymes for protein and nucleic acid metabolism and is essential for growth and formation of RBCs. Its deficiency leads to anaemia, failure of RBCs to mature and sprue. Vitamin B12 or cyanocobalamine acts as a coenzyme for nucleic acid metabolism and is essential for formation of RBCs and myelin formation. Its deficiency leads to pernicious (injurious) anaemia and malformation of RBCs.