Sources of iron

Dear Popeye and MD,

You can definitely find iron in foods other than spinach, that's for sure! Animal sources of iron include liver, kidneys, red meat, poultry, seafood (especially oysters and clams), and eggs. A few good plant sources of iron include peas, beans, nuts, leafy green vegetables (especially spinach), enriched pastas and breads, and fortified cereals. More specifically, MD, to satisfy your iron needs and your sweet tooth, you might seek out iron-rich fruits such as watermelon, raisins, strawberries, dates, figs, dried apricots, and peaches. Iron can also be found in prunes and prune juice. No matter the source though, your body’s ability to absorb iron from foods varies from about 3 to 40 percent, depending on its form in the food, the body's need for it, and a variety of other factors. It’s also good to know that, not all iron is created equal — iron from certain sources are more readily absorbed in the body than others (more on that in a bit). Beyond knowing what iron-rich food options you can stack on your plate, keep reading for more on what role iron plays in your body, how much you need of it, and how to maximize its absorption.

Iron is an essential mineral our body needs to function well. Iron is necessary for the formation of hemoglobin, which carries oxygen in the blood, and myoglobin, which carries oxygen in muscle. It is part of several enzymes and proteins in the body, is needed for immune function, and contributes to drug detoxification pathways in the liver.

To support these essential functions, you might also be asking how much iron is recommended. The recommended daily allowance (RDA) for iron is eight milligrams (mg) for adult men (ages 19 to 50) and 18 mg for adult women in the same age range. The higher dosage for women in this age range is primarily because of menstrual blood loss. After the age of 50, a woman's RDA is eight mg. If you don't take in enough iron, you can become iron-deficient. Iron deficiency is one of the most common nutrient deficiencies internationally, and is most common when iron needs are greatest in your life cycle — during infancy, preschool years, puberty, and during child-bearing years for women. Pregnancy and disease also increase iron needs. For more information, read up on Iron deficiency from the Go Ask Alice! archives.

Just knowing how much is enough isn't all there is to know about iron. The type of iron you’re taking in will determine how readily it can be absorbed. Iron from animal proteins, called heme iron, is more easily absorbed by the body than iron from plant foods, called non-heme iron.Your body will only absorb about two to ten percent of the non-heme iron. But, before you walk away from fruit or veggie snack to eat a steak, eating sources of heme iron along with sources of non-heme will help with absorption. So, if you’re meal planning, you might pair a piece of fish with a spinach and strawberry salad — yum! Research has also shown that eating non-heme iron sources with vitamin C-rich foods, such as citrus fruits, increases the body’s ability to absorb iron.

On the flip side, it's also good to know that some substances actually may interfere with iron absorption. These include phytates (found in soy protein, nuts, dried beans, cereals, and whole grain), calcium (found in dairy products, broccoli, and almonds), oxalates (found in spinach, nuts, chocolate, some herbs, and tea), and polyphenols (found in tannins in tea, coffee, nuts, and some fruits and vegetables).

Concerned about your iron intake? Having a chat with your health care provider may help you understand what your specific needs are when it comes to this nutrient. You might also consider making an appointment to speak with a registered dietitian or a health promotion specialist to strategize how to incorporate iron-rich foods into your diet if you feel it's lacking.