Chelated iron is iron that has undergone chelation, a chemical process that firmly binds the iron molecule to another substance, usually an amino acid. This forms a more stable ring-shaped molecule that is easier for plants and animals to absorb. Iron from dietary sources is bound to amino acids naturally, and chelation attempts to make supplemental iron more similar to these naturally occurring sources. Cells have membranes which allow some substances to pass through, while blocking others. Chelated iron, disguised as amino acids, is thought to pass through the cell membrane more easily, allowing the iron inside the cell where it is needed.