Iron is an important trace mineral that is found in every cell of the body, usually combined with protein. Iron is an essential mineral for humans because it is part of blood cells. About 30% of the iron in the human body is in storage to be readily available to replace any that is lost. The best food sources of easily absorbed iron are animal products, which contain heme iron. Iron from vegetables, fruits, grains, and supplements (non-heme iron) is harder for the body to absorb. If you mix some lean meat, fish, or poultry with beans or dark leafy greens at a meal, you can improve absorption of vegetable sources of iron up to three times. Foods rich in vitamin C also increase iron absorption. Iron is essential to the formation of hemoglobin and myoglobin, which carry oxygen in the blood and muscles. It also makes up part of many proteins and enzymes in the body. Iron sources that have high iron availability include oysters, liver, lean red meat (especially beef), poultry, dark red meat, tuna, salmon, iron-fortified cereals, dried beans, whole grains, eggs (especially egg yolks), dried fruits, and dark leafy green vegetables. Iron deficiency is the most common nutritional deficiency worldwide. Although full-blown anemia is rarely evident, partial deficiency is widespread.