The major function of iron in your body is oxygen delivery. Iron makes up the proteins that deliver oxygen to your tissues and your muscles. Adult men need 8 milligrams of iron per day, whereas adult women need 8 to 18 milligrams every day. It is helpful to note that eating vitamin C-rich foods -- such as oranges, green peppers, strawberries, broccoli, tomatoes and citrus juices -- with iron-rich foods helps increase the absorption of iron.
Clams are one of the richest sources of iron you can find. A 3-ounce serving of canned, drained clams contains 23.8 milligrams of iron and only 126 calories.
Also in the shellfish category and second on the list are oysters. A 3-ounce serving of oysters contains 10.2 milligrams of iron and 116 calories.
Organ meats, such as chicken and beef liver, also top the list of iron-rich foods. A 3.5-ounce serving of cooked chicken liver offers 12.8 milligrams of iron, and a 3.5-ounce serving of beef liver contains 8.75 milligrams of iron. The calorie count ranges from 134 to 235 per serving.
One half of a cup of cooked soybeans contains 4.4 milligrams of iron and 149 calories. If you have problems with estrogen, you should avoid eating soybeans in high doses.
Pumpkin seeds are more than just the guts of that jack o’lantern you’re carving. A 1-ounce serving of roasted pumpkin seeds contains 4.2 milligrams of iron and 148 calories.
A half-cup serving of canned white beans offers 3.9 milligrams of iron and 153 calories. As an added bonus, white beans are high in potassium.
Blackstrap molasses also makes the top 10 list. One tablespoon contains 3.5 milligrams of iron and 47 calories. It is also a rich source of calcium.
Lentils offer 3.3 milligrams of iron per half-cup serving. One serving of lentils is also rich in fiber and contains 115 calories.
Spinach is low in calories and one of the most iron-rich foods available. A half-cup serving of cooked (from fresh) spinach, contains 21 calories and 3.2 milligrams of iron.
Contrary to popular belief, beef is not the richest source of dietary iron, but it does make the top 10 list. The iron content of beef differs based on the cut. A 3-ounce serving of cooked beef chuck contains 3.1 milligrams of iron and 215 calories, whereas the same size serving of beef round contains 2.8 milligrams of iron and 182 calories. Beef rib offers 2.4 milligrams of iron and 195 calories.
In addition to the natural sources of iron listed above, fortified foods, such as dry cereals, also contain synthetic forms of iron. The amount of iron varies depending on the cereal but ranges from 1.8 milligrams to 21.1 milligrams, according to the Centers for Disease Control and Prevention.
Lindsay Boyers has a Bachelor of Science in nutrition from Framingham State College and a certificate in holistic nutrition from the American College of Healthcare Sciences. She is also a licensed aesthetician with advanced training in skincare and makeup. She plans to continue on with her education, complete a master's degree program in nutrition and, ultimately, become a registered dietitian.