The B group of vitamins is an eight-member family of water soluble vitamins which means they are not easily stored in the body and need to be replenished frequently. Their functions are so interrelated that it is suggested they be taken together so they can work harmoniously and perform at their peak levels. Cellular energy production is the most important function of the B complex vitamins and they are known as the catalytic spark plugs of our body. Providing mental and physical energy, supporting healthy blood, a healthy heart, immune system function and a healthy response to stress, the B complex vitamins are essential nutrients for the body.