Iron deficiency is the underlying cause of more than half of all cases of anemia. Since iron is used for more than 100 biochemical processes in the body, it’s not surprising that not having enough iron can cause more than a dozen symptoms. While taking an iron dietary supplement can help promote healthy levels of iron and healthy levels of oxygen-carrying red blood cells, making sure you’re eating iron-rich foods is also important.

The US Recommended Dietary Allowance (RDA) is the minimum amount of a nutrient required to prevent a deficiency in healthy people. The amount of dietary iron required depends on the body’s iron needs. The RDA for iron is highest for pregnant women (27 milligrams per day), followed by women aged 19-50 (18 milligrams per day) and then teenaged girls aged 14-18 (15 milligrams per day).  Women over the age of 50 and men over the age of 19 require 8 milligrams per day.

The United States National Institutes of Medicine (IOM) concluded that the average dietary intake of iron is 16 to 18 mg/day in men, 12 mg/day in pre- and postmenopausal women, and about 15 mg/day in pregnant women. Thus, the majority of premenopausal and pregnant women in the US consume less than the recommended daily amount (RDA) for iron, and many men consume more than the RDA.

This means that, over time, women, especially menstruating women, are at a high risk for iron deficiency and developing iron deficiency anemia.

There are 2 different forms of iron in foods: heme iron and nonheme iron. Heme iron is present in animal foods, and nonheme iron is present in plant foods. Heme iron is better absorbed than nonheme iron, but the bulk of iron in a typical diet comes from plant sources, in the nonheme form. Some of the richest sources of dietary iron include oysters, beef, lentils, beans and dark chocolate (see table 3). Also consider cooking in a cast iron skillet, as some of the iron will transfer into your food as it cooks.