B complex vitamins participate in many physiological functions and are important for the maintenance of the health of the human body. Vitamins B1, B2, B3, B6, B7 and B12 contribute to normal functioning of the nervous system. B complex vitamins contribute to the normal function of the immune system (B6, B9 and B12),normal psychological function (B1, B3, B7, B9 and B12), contribute to the reduction of tiredness and fatigue (B2, B3, B5, B6, B9 and B12) while vitamin B5 contributes to normal mental performance. Vitamin B1 contributes to normal function of the heart, and vitamin B2 contributes to the maintenance of normal vision.