The vitamin b complex refers to all of the known essential water soluble vitamins except for vitamin ceach member of the b complex has a unique structure and performs unique functions in the human body vitamin b1 b2 b3 and biotin participate in different aspects of energy production vitamin b6 is essential for amino acid metabolism and vitamin b12 and folic acid facilitate steps required for cell division each of these vitamins has many additional functionscontributes to normal energy yi