Ferrous Glycinate, also known as iron bisglycinate, is a mineral amino acid chelate in which a ferrous iron ion is coordinated with two molecules of glycine. This chelation protects the iron from interactions with dietary inhibitors such as phytates, tannins, and polyphenols that typically reduce iron absorption. Clinical studies have demonstrated two to four times greater bioavailability than ferrous sulfate. The chelated form is significantly better tolerated, with lower incidence of constipation, nausea, and gastric distress.