I take magnesium through Nutrition For Life as i like the higher quality products i believe they give me. Let me read you info from the book Prescription for Nutritional Healing on magnesium(some of the more interesting info). is a vital catalyst in enzyme activity(especially energy production.) assists calcium and potassium uptake. deficiency interferes with transmission of nerve and muscle impulses causing irritability and nervousness. supplementing can help prevent depression,dizziness,muscle weakness and twitching ,PMS,and maintaining the body's proper PH balance. deficiency symptoms include: confusion,insomnia,irritability,poor digestion,rapid heartbeat,seizures,tantrums,cardiac arrhythmias, and hypertension. a better screening test to ask for is intracellular(mononuclear cell) magnesium screen test-is more sensitive than the serum mag.test. the consumption of alcohol,use of diuretics,presence of fluoride,birth control pills, and high levels of zinc/vit D increase the body's need for magnesium. Be sure NOT to take it after a meal as it neutralizes stomach acids. I take mine when i first get up on empty stomach. Hope this helps!!A lover of alternative medicine/prevention! azpam