Iron is strong, and it’s tough — superhero tough. By mass, it’s the most common element on Earth, and supernova explosions result when the cores of massive stars exhaust their fuel supplies, having burned everything into iron and nickel.
But the metal also has another small-scale but vitally important role in our everyday lives: iron is an essential nutrient for our bodies.
That’s so metal
Iron is a major component of hemoglobin, the molecule in red blood cells that carries oxygen from our lungs and to every part of us — from nose to toes, uterus to uvula (the thing that hangs down in the back of your throat). It also helps muscles store and use oxygen, and is part of many other proteins and enzymes.
When you don’t get enough iron into your body, you can become anemic, which makes you feel tired and generally fatigued. Iron deficiency anemia affects nearly 2 billion people worldwide, most often pregnant women, premature babies and young children, Dennis J Thiele PhD, the George Barth Geller Professor of the Duke University Department of Pharmacology and Cancer Biology, noted in 2008.
Anemia does more than make you feel out of energy — Thiele says it can profoundly affect cognitive development, as well as motor and neuronal development.
But why would you be anemic? Common causes of low iron levels include blood loss (including from your period), poor diet, or an inability to absorb enough iron from foods.
The good news is that, with a little planning, you should be able to get all the iron you need from the foods you eat.
A sampling of iron-rich foods
- Seafood: Fish (cod, sardines, tuna) and some shellfish (clams, oysters, shrimp)
- Poultry: Chicken, eggs, yolk
- Lean red meats: Beef, lamb, veal, pork, liver
- Nuts: Hazelnuts, almonds, peanuts
- Beans: Soybeans, dried beans, lentils, lima beans, peas, chick peas (garbanzo beans)
- Vegetables: Broccoli, chard, greens, asparagus, turnips, parsley, kale, watercress, Brussels sprouts
- Fruits & treats: Dates, prunes, figs, apricots, apples, raisins, dark chocolate, coconut
- Bread and cereals: Enriched, fortified and whole grain breads and cereals are often high in iron (check label)
- Grains: Wild rice, corn meal, oats, soy, wheat, bran, rye, buckwheat, popcorn, barley, wheat germ, millet
- Cereals: Farina, Cream of Wheat, Shredded Wheat
Tips to get a little more iron into your everyday diet
While it’s definitely possible to gain iron from non-animal foods, Dr Thiele says, “Iron is hard for humans to get from plant sources, which form the basis for most of the world’s diet.”
Here are a few ways to help.
- Eat vitamin-C foods together with iron-rich foods to help your body better utilize iron. For example, eat an orange or strawberries with your cereal, add tomato to your hamburger, serve up some red bell pepper with some spinach, or add some salsa to a burrito or taco.
- Cook vitamin-C foods and iron-rich foods together — like add some chilies to your favorite bean recipe, or stir up a steak with tomatoes and peppers.
- When preparing dry beans, soak beans for several hours in cold water before you cook them. Pour off the water, and use new water to cook the beans.
- Don’t use too much water to boil iron-rich foods, and don’t overcook them.
- Prepare foods in cast iron skillets, pots or pans to add extra iron to your food. Acidic foods with a higher moisture content — like tomato sauce or a balsamic vinegar glaze — will absorb the most iron.
- For about 3 hours before and after consuming iron-rich foods, avoid foods and substances that inhibit iron absorption — notably calcium, coffee & tea, and bran.
- Sweetness: Sweet blackstrap molasses — known to many of us as the flavor difference between white and brown sugar — is rich in iron. Also, a 101-gram serving of dark chocolate (with 70-85% cacao solids) contains about 67% of the US RDA of iron… although that much also has more than 600 calories.
If you’re not vegetarian/vegan, eating a small amount of meat with other foods can increase the iron your body can get from other foods. For example, try putting a small amount of ground beef or bacon into your cooked beans.
Iron-rich foods: Dietary sources of iron
Below are some top food sources of iron ranked by milligrams of iron per standard amount.
|Food, Standard Amount||Iron (mg)||Calories|
|Clams, canned, drained, 3 oz||23.8||126|
|*Fortified dry cereals (various), about 1 oz||1.8 to 21.1||54 to 127|
|Cooked oysters, cooked, 3 oz||10.2||116|
|Organ meats (liver, giblets), cooked, 3 oz||5.2 to 9.9||134 to 235|
|*Fortified instant cooked cereals (various), 1 packet||4.9 to 8.1||Varies|
|*Soybeans, mature, cooked, 1/2 cup||4.4||149|
|*Pumpkin and squash seed kernels, roasted, 1 oz||4.2||148|
|*White beans, canned, 1/2 cup||3.9||153|
|*Blackstrap molasses, 1 Tbsp||3.5||47|
|*Lentils, cooked, 1/2 cup||3.3||115|
|*Spinach, cooked from fresh, 1/2 cup||3.2||21|
|Beef, chuck, blade roast, cooked, 3 oz||3.1||215|
|Beef, bottom round, cooked, 3 oz||2.8||182|
|*Kidney beans, cooked, 1/2 cup||2.6||112|
|Sardines, canned in oil, drained, 3 oz||2.5||177|
|Beef, rib, cooked, 3 oz||2.4||195|
|*Chickpeas, cooked, 1/2 cup||2.4||134|
|Duck, meat only, roasted, 3 oz||2.3||171|
|Lamb, shoulder, cooked, 3 oz||2.3||237|
|*Prune juice, ¾ cup||2.3||136|
|Shrimp, canned, 3 oz||2.3||102|
|*Cowpeas, cooked, 1/2 cup||2.2||100|
|Ground beef, 15% fat, cooked, 3 oz||2.2||212|
|*Tomato puree, 1/2 cup||2.2||48|
|*Lima beans, cooked, 1/2 cup||2.2||108|
|*Soybeans, green, cooked, 1/2 cup||2.2||127|
|*Navy beans, cooked, 1/2 cup||2.1||127|
|*Refried beans, 1/2 cup||2.1||118|
|Beef, top sirloin, cooked, 3 oz||2.0||156|
|*Tomato paste, 1/4 cup||2.0||54|
Food sources of iron are ranked by milligrams of iron per standard amount; also calories in the standard amount. (All amounts listed provide 10% or more of the Recommended Dietary Allowance [RDA] for teenage and adult females, which is 18 mg/day.)
* These are non-heme iron sources. To improve absorption, eat these with a vitamin-C rich food. (See more info about bioavailability & absorption below.)
How to make sure you’re getting the most from your iron sources
Dietary iron has two main forms: heme and nonheme. Plants and iron-fortified foods contain nonheme iron only; whereas meat, seafood, and poultry contain both heme and nonheme iron. The richest natural sources of heme iron in the diet are lean meat and seafood.
Heme iron has higher bioavailability — that is, the percentage of the nutrient that your body can actually absorb — than nonheme iron, and other dietary components have less effect on the bioavailability of heme than nonheme iron.
The bioavailability of iron is approximately 14% to 18% from mixed diets that include substantial amounts of meat, seafood and vitamin C (ascorbic acid, which enhances the bioavailability of nonheme iron), and 5% to 12% from vegetarian diets.
In addition to ascorbic acid, meat, poultry and seafood can enhance nonheme iron absorption, whereas phytate (present in grains and beans) and certain polyphenols in some non-animal foods (such as cereals and legumes) have the opposite effect. Unlike other inhibitors of iron absorption, calcium might reduce the bioavailability of both nonheme and heme iron.
Coffee may diminish iron absorption, while commercial black tea or pekoe teas contain substances — tannins — that bind to iron so it cannot be used by the body. Furthermore, some plant-based foods that are good sources of iron, such as spinach, actually end up having low iron bioavailability because they contain iron-absorption inhibitors, such as polyphenols.
Overall, you see, it’s not just how much iron you have, but what you do with it that makes all the difference.