Are You Getting Enough Iron?

Spinach in cast iron panIron is the most abundant element on Earth, yet iron deficiency is the most common nutritional disorder both in the United States and the world, according to the World Health Organization.

Iron is critical to our bodies’ ability to deliver oxygen and for proper metabolism that feeds our muscles and other organs. Women, babies, and seniors are at the highest risk for iron deficiency and anemia, which can cause decreased energy and cognitive function, and depress the immune system. But following some simple guidelines can ensure your iron levels are sufficient. Eating a balanced, healthy diet supplies plenty of iron, even for vegetarians.

Red meat is an excellent source of iron, but you need not adopt a T-bone-only diet to get your quota of iron. Iron deficiency is as high among meat eaters as vegetarians. There are many other sources of iron-rich foods, including clams, blackstrap molasses, thyme, and turmeric. Half a cup of spinach, lentils, or garbanzo beans (chickpeas) has more iron than three ounces of sirloin or ground beef. Oysters and organ meats, especially chicken liver, are also near the top of the list of iron-rich foods but contain less iron than three tablespoons of blackstrap molasses. Some other surprisingly rich sources of iron are spices and herbs: one teaspoon of cumin provides 15% of the Daily Value (DV) for iron, while one teaspoon of thyme offers 10% of the DV. Turmeric, oregano, black pepper, and basil are also concentrated sources of iron. For a complete list of iron-rich foods, visit the National Institutes of Health iron fact sheet.

Knowing what foods are good sources of iron is only part of the story. There are two types of iron found in foods: Animal sources of iron (heme iron), which are more absorbable by our bodies, and plant sources of iron (non-heme iron). You can boost the body’s absorption of non-heme iron by consuming foods high in vitamin C along with them.

How food is prepared also affects its iron content. Boiling vegetables can remove a significant portion of the iron content. For instance, boiling spinach for over three minutes in a large pot removes almost 90 percent of the iron from its leaves. To minimize iron loss when cooking veggies, try steaming instead of boiling and use shorter cooking times.

Cast iron cookware can increase the amount of iron in foods, according to a 1986 study published in the Journal of the American Dietetic Association. Acidic foods, such as tomato sauce, leach iron from the pan in an absorbable form, and can increase iron amounts substantially. For example, spaghetti sauce went from 0.61 milligrams iron to 5.77 milligrams iron per 100 grams of sauce when cooked in cast iron. Non-acidic foods still leach significant amounts. The study found that white rice cooked in an iron pan increased from 0.67 milligrams to 1.97 milligrams iron. (See also Heavy Metal: The Science of Cast Iron Cooking.)

There are significant variations in the recommended iron intake for different groups by age and sex. Adult men require only 8 milligrams per day of iron, while adult women require 18 milligrams per day, due to menstruation. Times of high growth in infancy and during teen years, for both boys and girls, mean higher iron needs. Pregnancy is another time that calls for increased iron needs.

Below are the recommended dietary allowances for iron in all segments of the population:

RDA chart for iron
The recommended dietary allowances (RDA) for iron in all segments of the population by age and sex.

Source: Dietary Reference Intakes, Institute of Medicine, Food and Nutrition Board

It is important to remember that iron can also be toxic in high doses. It is unlikely to happen through a regular diet, but iron supplements are a common cause of iron overload. Be especially careful of supplements around children, who require less iron than adults (although most children’s vitamins do not contain iron unless otherwise stated on the label). Also note that most supplements provide 18 milligrams of iron, the women’s recommended dietary allowance, which is more than men and children need.

Why We Need Iron

An elemental component of the protein hemoglobin, iron transports oxygen throughout our bodies to each of our cells, which in turn use the oxygen to produce energy. If our body’s iron stores fall low enough, we develop iron deficiency anemia, which impairs our production of hemoglobin. Symptoms of anemia can include feeling grumpy or irritable; feeling weak or more tired than usual, especially with exercise; headaches; and problems concentrating or thinking. If the anemia progresses, additional symptoms may include a blue tinge to the whites of the eyes; brittle nails; light-headedness upon standing; pale skin color; shortness of breath; and/or a sore tongue.

About two-thirds of the body’s iron is in the form of hemoglobin. Either a hemoglobin test or a hematocrit test (the percentage of red blood cells in your blood by volume) can be used to test for anemia.

Because of the way iron is used in our muscles, iron deficiency can cause fatigue before it develops into anemia. The protein myoglobin performs the same task for our muscles that hemoglobin performs for our blood—storing and using oxygen. If we lack sufficient iron, we can experience muscular and general fatigue long before the deficiency is serious enough to show up as anemia, or even as decreased hemoglobin on a blood test. As much as 80 percent of the world’s population may be iron deficient, while 30 percent may have iron deficiency anemia, according to the 2001 study published in the Journal of Nutrition.

Anemia and low iron can steal your energy, but you can stay healthy by making sure to eat a variety of iron-rich foods regularly. Remember these tips:

  • Eat iron-rich foods such as dark leafy greens, legumes, red meats, clams, oysters, blackstrap molasses, thyme, basil, cumin, turmeric, and black pepper.
  • Steam leafy vegetables instead of boiling and decrease cooking times.
  • Cook in cast iron cookware.

If you suspect you may have iron deficiency or anemia, speak to your doctor or health care provider. Always consult your doctor before making significant dietary changes.

Rebecca Taggart is a San Francisco-based writer, teacher, and yoga instructor.

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