Best Magnesium supplement for your brain and body Magnesium is needed for the activation of over 300 enzymes in the body and is required for proper nerve function, heart rhythm, bone integrity and muscle relaxation. Sadly, 2 out of 3 Americans do not obtain enough Magnesium from the food they eat, according to the U.S. Dept. of Agriculture. Even when you eat a healthy diet, only half of the Magnesium you ingest is fully absorbed.† Liquid Magnesium gives you the highest concentration of Magnesium Most Magnesium is found within the body’s cells and is nearly impossible to measure with the use of blood tests. Mag Chlor 90 is a liquid Magnesium supplement that gives the highest concentration of Magnesium available without a doctor’s prescription.