Nearly everyone as they get older becomes deficient in Magnesium. This may be due to depletion of this vital mineral from our soils. Testing is not helpful usually, because, by the time blood studies detect a deficiency, cells have been low for decades. Deficiency, even before a low level appears on blood studies results in leg cramping, constipation, inadequate calcium handling, bone fragility, and contributes to hypertension and neurologic impairment. Not all forms of magnesium are well absorbed. Do not take Magnesium Oxide which has the worst absorption. Use either Magnesium malate, Magnesium Citrate, or Magnesium Glycinate. Magnesium glycinate makes you sleepy so take it at night. Any form of Magnesium may cause loose stools at first as the bowel improves its peristalsis (squeezing). If you do have frequent or loose stools, take smaller doses and work slowly up to the recommended 400-800 mg/ day. Even larger doses can be taken to reduce blood pressure.