Magnesium - is an essential mineral needed for bone, protein and fatty acid formation. It is also needed to make new cells, activate B Vitamins, relaxing muscles, clotting blood and the formation of the energy molecule ATP. Magnesium deficiency can cause many problems including fatigue, abnormal heart rhythms, muscle weakness and pain, depression, loss of appetite, listlessness and potassium depletion. Nuts, grains, beans, dark green vegetables and fish contain significant amounts of Magnesium.