Best Naturals Magnesium Chloride 520 mg 120 Tablets. Magnesium is a mineral that is critical for energy production and metabolism muscle contraction nerve impulse transmission and bone mineralization. It is a required cofactor for an estimated 300 enzymes. Among the reactions catalyzed by these enzymes are fatty acid synthesis protein synthesis and glucose metabolism. Magnesium status is also important to regulate the balance of calcium sodium and potassium in our cells particularly in our heart and blood vessels.*