Magnesium and 8 B-complex vitamins are added to For Nerves and Muscles. Magnesium contributes to normal muscle function. Magnesium and vitamins B1, B2, B6, B12, biotin and niacin contribute to normal nervous system function. In addition, magnesium and vitamins B2, B6, B12, folic acid, niacin and pantothenic acid help to reduce tiredness and fatigue.