Magnesium is a cofactor in over 300 metabolic reactions. It is involved in the maintenance of muscle function, glucose metabolism and muscle contraction, among several other important physiological roles.3 Magnesium helps to maintain bone health by regulating the production of parathyroid hormone (PTH) and calcitriol, which helps to increase calcium absorption and minimize risk of calcium deficiency.4,5 In the United States, insufficient magnesium intake is estimated to occur in approximately 64% of men and 67% of women, with even higher levels of insufficient intake in elderly individuals.6 Magnesium glycinate (also known as magnesium bisglycinate) is a highly water soluble amino acid chelate of magnesium and two glycine molecules. Clinical evidence indicates that magnesium glycinate has a significantly higher bioavailability than magnesium oxide, and is less likely to cause a laxative effect.1,2 Supplementation with magnesium glycinate has been shown to decrease the severity of muscle cramping: in a clinical trial on 86 healthy pregnant women with recurrent muscle cramps, supplementation with 300 mg of magnesium glycinate for 4 weeks reduced both the frequency and intensity of leg cramps.2