Why are biotin and panthothenic acid and vitamin B12 not required in the diet?

Biotin, pantothenic acid and vitamin B12 or cyanocobalamin are all B vitamins. All vitamins including these three are essential and we must get them in our diets for good health. Without these vitamins, we would suffer from symptoms associated with deficiencies and after a long time, eventually die without them. This is why they are essential.