Iron is an essential mineral that is part of several important proteins in the body. It is found in hemoglobin, which transports oxygen in red blood cells, and myoglobin, which stores oxygen in muscle tissue. Iron is also involved in oxygen transport within cells through cytochromes and is necessary for the function of many enzymes related to amino acid synthesis, carbohydrate metabolism, DNA synthesis, and metabolism of lipids, steroids, and drugs. The absorption of iron is affected by an individual's iron status and can be increased by vitamins C and A or decreased by oxalic acid and phytic acid/polyphenols.