By Dena McDowell, MS, RD

Iron is one of the most important minerals stored in the body. It is an “essential” mineral, which means that we must consume it as part of a healthy diet—the body does not make enough by itself. Two thirds of iron is stored as hemoglobin, which is a protein responsible for the delivery of oxygen to cells; the rest is stored as myoglobin in the muscles, or as part of the enzymes that are responsible for chemical reactions in the body. Iron aids with cell growth and immune function as well.

High risk groups for iron deficiency

According to the World Health Organization, iron deficiency is the number one nutritional problem in the world. It is estimated that 80% of the world’s population is iron deficient, and of that number 30% are anemic. Iron deficiency can be corrected by consuming an iron-rich diet and supplementing with iron tablets. Groups greatest at-risk include:

• Women of childbearing age (due to loss associated with menstrual blood)
• Pregnant women (due to increased blood flow)
• Pre-term and low birth weight infants (due to inadequate storage of iron)
• Toddlers (due to limited food choices)
• Teenage girls (due to poor dietary intake and menstrual losses)
• Patients who suffer from kidney failure requiring dialysis (due to blood filtration)
• People suffering from Crone’s or celiac disease (due to poor gastrointestinal absorption)
• Vegetarians and athletes (due to poor dietary intake)

Athletes, especially young women, are often at a higher risk of deficiency. Multiple factors contribute to this problem, including poor dietary intake, poor absorption, increased gastrointestinal blood loss, increased red blood cell turnover due to a higher oxygen capacity, and possibly due to red blood cell rupture in the feet of runners.

Symptoms of iron deficiency

Signs and symptoms of low iron stores include: fatigue, weakness, slow cognitive function, poor work or school performance, impaired immunity, difficulty regulating one’s body temperature and in severe cases a swollen tongue known as glossitis. Below is a chart of the Recommended Daily Allowance (RDA) for iron.

RDA for Iron

	Male	Female	Pregnancy
7-12 months	11	11
1-3 years	7	7
4-8 years	10	10
9-13 years	8	8
14-18 years	11	15	27
19-50 years	8	18	27
51 plus years	8	8

* All amounts are in milligrams per day.

Iron is absorbed at different rates

Dietary iron comes in two forms:

1. Heme iron is found in animal products such as meats, poultry and fish. Heme iron is well absorbed in the body (15-35%) compared to non-heme sources (2-20%).
2. Non-heme iron is found in plant sources, including legumes (beans), lentils, leafy greens and enriched food products.

It is recommended to add vitamin C when eating non-heme iron sources to increase it’s availability in the body. One example of this would be to drink orange juice when eating a spinach salad. Iron absorption is dose-dependent, meaning that the body will absorb more if iron stores are low. Eating a diet rich in tannins (from tea), calcium, or phytates (from vegetables) impairs iron absorption. Below is a list of common food sources.

Common Food Sources of Iron

Food Source	Amount of Iron (mg)
Fortified cereal, ¾ cup	18
Chicken liver, cooked, 3.5 oz.	12.8
Fortified oatmeal, 1 cup	10
Soybeans, boiled, 1 cup	8.8
Lentils, cooked, 1 cup	6.6
Kidney beans, cooked, 1 cup	6.6
Lima beans, cooked, 1 cup	4.5
Oysters, 3.5 oz.	4.5
Black beans, cooked, 1 cup	3.6
Black Strap Molasses, 1 Tb.	3.5
Tofu, raw firm, ½ cup	3.4
Beef, chuck, 3.5 oz.	3.2
Spinach, fresh boiled, ½ cup	3.2
Turkey, dark meat, 3.5 oz.	2.3
Spinach, frozen boiled, ½ c.	1.9
Turkey, light meat, 3.5 oz.	1.6
Grits, prepared with water, 1 cup	1.5
Raisins, ½ cup	1.5
Chicken breast, 3.5 oz.	1.1
Bread, enriched, 1 slice	0.9
Pork loin, 3.5 oz.	0.8
Tuna, white packed in water, 3 oz.	0.8

*Adapted from www.nal.usda.gov/fnic/cgi-bin/nut_search.pl

Should you take an iron supplement?

Female athletes or those who follow a vegetarian diet should ensure their diets are rich in iron. If not, then taking a multivitamin with 100% of the RDA for iron is recommended. Another good reason to take an iron supplement is if you’re diagnosed with an iron deficiency anemia. Ideally, you should take your iron supplements at night—your chances of experiencing adverse side effects are lessened if you do. Potential side effects include intestinal cramping, nausea, vomiting, constipation or diarrhea. Iron supplements now come in slow release tablets, which are easier to digest. Speak to your physician or pharmacist for more information.

If you’re already taking an iron supplement, remember it’s still important to incorporate iron rich foods into your diet so that your body becomes accustomed to digesting dietary sources of iron; when you eventually discontinue use of iron supplements your body will adjust easier.