Iron is a mineral that plays a key role in many processes essential for human health. For example, iron helps young brains and bodies grow and develop, maintains energy levels, and supplies organs and tissues with oxygen. In this guide, we dig into how iron works in the body, where to get the nutrient, and what happens if you don’t get enough.
“Iron is incredibly important for kids’ growth and development,” says Sarah Gold Anzlovar, RDN, the owner of Sarah Gold Nutrition, a virtual private nutrition practice in Boston. “As adults, getting enough iron helps you have enough energy for your day, can support exercise goals, helps your body make hormones, and plays a role in many important body functions.” Iron’s main claim to fame is that it’s a major component of hemoglobin, the protein in red blood cells that’s responsible for transporting oxygen to your organs and tissues.
But some groups of people may need to aim higher than the DV. Namely, pregnant teens and women. The amount of blood in the body increases during pregnancy, and more blood calls for more iron to deliver oxygen to the fetus and reproductive organs, according to the Academy of Nutrition and Dietetics. For this reason, it’s recommended that pregnant teens and women get 27 mg of iron per day.
People who follow a mostly plant-based diet may need more than the DV for iron, as the body doesn’t absorb iron in plant foods as well as iron in animal foods.
Your body can’t make iron, so it’s vital to get iron from external sources such as food and supplements.
Iron in food comes in two forms: heme iron, which is found in animal sources, and nonheme iron, which is present in plant sources. Your body absorbs two to three times more iron from animal sources than from plants. This is why people who follow a plant-based diet may need to increase their iron intake beyond the recommended 18 mg per day. The RDA for vegetarians, for example, is 1.8 times higher than for meat eaters.
As the NIH notes, some of the best animal sources of iron include:
You can find iron in the following plant-based sources, according to the Academy of Nutrition and Dietetics:
Adding a food that’s rich in vitamin C can help you absorb more of the iron in plants, the NIH notes. The following foods are all excellent sources of vitamin C:
Some people may benefit from an iron supplement, according to the National Heart, Lung, and Blood Institute (NHLBI) — namely, people with an iron deficiency or those who face a higher risk of deficiency. “This includes pregnant women, women with heavy menstrual periods, vegans and vegetarians, and endurance athletes, especially female athletes,” Gold Anzlovar says.
Pregnant women can benefit from getting 27 mg of iron per day, per the NIH. Recommended dosages among other groups may vary.
Be sure to check with your doctor before taking an iron supplement. “Iron can be a toxic mineral [at high doses], so it’s better to test rather than guess,” Asbury says.
If you suspect you have an iron deficiency, your doctor may suggest a blood test to measure your complete blood count, hemoglobin levels, blood iron levels, and ferritin levels (ferritin is a type of protein that stores iron inside your cells). If the test shows your iron levels are low, your doctor may suggest that you take an iron supplement.
Keep in mind that although they’re monitored for safety concerns after their release, dietary supplements aren’t regulated by the U.S. Food and Drug Administration (FDA) for safety and efficacy. Instead, it’s up to manufacturers and distributors to ensure their product is safe before they’re sold — another reason it’s a good idea to consult with a healthcare professional before using a supplement.
Iron offers many perks when consumed in healthy amounts. If you’ve been diagnosed with iron deficiency, restoring your iron to a healthy level will probably lead to the following benefits.
Those deficient in iron often feel tired, per the NIH. When your body doesn’t have enough iron to make hemoglobin, which carries oxygen around your body, there's less oxygen for your muscles and tissues, depriving them of energy. The result: fatigue. Shoring up your iron stores with plenty of iron-rich foods — and an iron supplement, if needed — may help keep tiredness and lethargy at bay.
The hemoglobin provided by iron benefits your brain, too. Research shows that concentration and attentiveness are affected almost immediately by a drop in iron. If you can restore your iron levels to a normal range, you may see improvements in concentration and cognitive performance.
“Active individuals benefit from having adequate iron stores to support optimal endurance,” says Laura Asbury, RDN, CSCS, who is affiliated with Nutrition in Motion in Bedford, New Hampshire. The reason? Iron plays an important role in creating myoglobin, a protein that supplies oxygen to your muscles.
In a study published in the January 2019 Journal of Nutrition, sedentary women with low iron stores, though not clinical iron deficiency, who supplemented with iron saw greater improvements in endurance than women who didn’t supplement. Nevertheless, a large review of studies published in the September–October 2018 issue of Sports Health that looked at iron supplementation for athletes suggests these effects don't always occur, and more research is needed in this area. Talk to your doctor if you’re interested in using iron pills to bolster athletic performance.
Iron deficiency is fairly common. Research shows that about 10 million people in the United States and two billion people worldwide are iron deficient.
If your body goes without the needed amount of iron for long enough, you may notice symptoms. And once symptoms present, chances are your iron deficiency has progressed to iron deficiency anemia, according to the Academy of Nutrition and Dietetics. This is a condition in which your body’s iron stores are too low to make hemoglobin. As the Mayo Clinic explains, hemoglobin is what gives blood its red color and enables your red blood cells to carry oxygen throughout your body.
Various factors can contribute to iron deficiency, notes the NHLBI. The following groups of people are more likely to develop iron deficiency.
Certain health conditions may also increase your risk of iron deficiency, including:
“One of the earliest signs of iron deficiency is unexplained extreme fatigue,” says Gold Anzlovar. “If you feel like you're more tired than usual, can't get through your normal daily activities, or your regular exercise feels particularly difficult for no reason, you may be iron deficient.”
According to Mayo Clinic, other signs and symptoms of iron deficiency, or iron deficiency anemia, include:
Talk to your doctor if you notice any of these symptoms or suspect you have an iron deficiency, advises Intermountain Healthcare.
To diagnose iron deficiency anemia, your doctor may ask about your medical history and risk factors (such as diet, menstruation, and family history of anemia) and order a blood test. The test checks your complete blood count, hemoglobin levels, blood iron levels, and ferritin levels. According to the NHLBI, normal iron levels fall between 10 and 30 micromoles per liter (mcmol/L) and ferritin between 40 and 300 micrograms per liter (mcg/L) for men and 20 to 200 (mcg/L) for women. If you have iron deficiency anemia, your results will show less than 10 mcmol/L of iron and/or less than 10 mcg/L of ferritin.
Your doctor may also examine your red blood cells under a microscope. People with iron deficiency anemia have pale red blood cells instead of the standard bright red, notes the Cleveland Clinic.
According to the NHLBI, the most common treatment for iron deficiency anemia is iron supplements, which you may also hear referred to as iron pills. It often takes three to six months of supplementation to get your iron levels within a healthy range. Your doctor may also recommend eating more iron-rich foods, such as beans, eggs, iron-fortified breads and cereals, and green leafy vegetables.
If you have severe iron deficiency anemia or a long-term medical condition, you may receive a blood transfusion or receive intravenous (IV) iron. The IV treatment injects iron through one of your veins and may restore your iron levels after only a few sessions, per the NHLBI.
There are also medicines — such as an erythropoiesis stimulating agent — that can help your bone marrow make more red blood cells.
The longer your anemia goes untreated, the more intense the symptoms can become, and the greater your risk of heart complications. Without enough red blood cells, your heart has to work harder to deliver the oxygen your body needs. This extra work can cause the wall of your heart muscle to thicken, leading to a serious condition called left ventricular hypertrophy (LVH). LVF can require hospitalization and sometimes cause death.
According to the NIH, it’s recommended that adults get no more than 45 mg of iron per day, though a doctor may prescribe a higher amount to people who have been diagnosed with an iron deficiency.
While iron is beneficial within normal ranges, it can have unpleasant or even severe effects at high levels.
“Iron overload typically happens from taking high amounts of iron supplements,” Gold Anzlovar says. For this reason, it’s important to consult a doctor before taking an iron supplement, and to take only the amount prescribed.
Iron toxicity can also be caused by hemochromatosis, a genetic condition that causes iron to build up in the body, according to the NIH. If left untreated, hemochromatosis can cause severe medical problems, including liver cirrhosis, liver cancer, and heart disease. These folks should steer clear of iron supplements and vitamin C supplements.
Iron can be dangerous in high amounts. According to MedlinePlus, overdosing on iron supplements can cause many symptoms, including:
Some symptoms may go away in a few hours, but they will return again a day or so later. Seek emergency medical treatment if you notice any of these symptoms.
In the short-term, high doses of iron can cause gastrointestinal (GI) symptoms, such as stomach upset, constipation, nausea, vomiting, abdominal pain, and diarrhea, per the NIH.
Over time, high doses of iron can reduce your body’s ability to absorb zinc, thereby increasing your risk of a zinc deficiency, says Gold Anzlovar. Zinc is another mineral, and it plays an important role in immune function, wound healing, and the creation of protein and DNA. Zinc deficiency can lead to loss of appetite, lowered immune function, weight loss, mental lethargy, delayed wound healing, diarrhea, and hair loss.
Taking in more iron than your body can absorb can also cause inflammation in the GI tract, which can lead to poor nutrient absorption, disruption to the gut microbiome (the bacteria and other microorganisms in your digestive tract), and greater inflammation elsewhere in the body, Bohnengel says. Any one of these scenarios could have long-term consequences for your health. Research suggests that chronic inflammation, for example, causes and worsens many common diseases, from cancer to heart disease to pancreatitis. Meanwhile, malabsorption can affect growth and development, or it can lead to specific illnesses, notes Johns Hopkins Medicine. Changes in the gut microbiome can also have negative effects, especially if the balance between helpful and potentially harmful bacteria gets thrown off. If that happens, you may face a greater risk of disease, according to Harvard Health.
At extremely high doses — in the hundreds or thousands of milligrams — iron can cause organ failure, convulsions, and death, notes the NIH.
To avoid iron toxicity, don’t oversupplement. Be sure to work with your healthcare team before taking a supplement, and if they determine you need one, ask them what dosage you need to take. Getting your iron levels tested regularly via blood samples can also be helpful.
Severe iron overdoses are typically treated at the emergency room. According to MedlinePlus, treatment may include:
