When the deficiency is severe, symptoms include confusion, disorientation, belligerent behavior, convulsions, and hallucinations. Good sources include seeds, nuts, whole grains, and cooked green leafy vegetables. Magnesium is lost when the water from cooking vegetables is discarded, or when foods are overcooked. It is also wasted when too much sugar or salt is consumed. If your child consumes excessive calcium, a magnesium deficiency is created.
Many children consume lots of milk but few whole grains or cooked greens.
Children who obtain little calcium will also have magnesium deficiency as a result. Soils east of the Mississippi River are usually low in magnesium, and chemical fertilizers make the magnesium in the soil unavailable to the plants. Antibiotics can waste a remarkable amount of magnesium, especially when high or prolonged doses are taken. I have personally experienced frightening auditory and visual hallucinations while taking antibiotics. Fortunately, the symptoms quickly abated when I took 300 mg. of powdered magnesium oxide.