Natural Magnesium Supplement for Metabolism, Bones, and Nerves. Magnesium is an essential mineral for calcium and potassium assimilation, and helps support proper nerve muscle impulses, enzyme reactions, bone health and carbohydrate metabolism. Twinlab magnesium 420 milligrams capsules play an important role in maintaining bone mineralization and protein formation. Magnesium 420 milligrams capsules are also a cofactor for more than 300 biochemical reactions within the body that leads to efficient fatty acid synthesis, protein synthesis, calcium balance regulation and many other processes.