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Iron has many benefits and is one of the most important minerals for your body. Iron is needed to produce hemoglobin and myoglobin. Hemoglobin helps red blood cells (RBCs) carry oxygen throughout the body, and myoglobin is a protein that helps provide oxygen to the cells in your muscles.
While all human cells contain iron, it is mostly found in RBCs.
Iron supplements play a vital role in treating anemia (low levels of healthy RBCs), particularly iron deficiency anemia (IDA). Most people get all the iron they need from their diets. However, some may be prone to iron deficiency. Iron deficiency is the most common cause of anemia, occurring in 7.6% of non-pregnant females and 3.6% of males in the U.S.
This article explains what iron does for your body and when iron supplementation might be appropriate.
In the United States, the Food and Drug Administration (FDA) does not regulate supplements like prescription drugs. That means some supplement products may not contain what the label says.
When choosing a supplement, look for third-party tested products (such as the USP, Consumer Labs, or NSF) and consult a healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.
Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.
Iron supplementation primarily works to restore low iron levels. Treating iron deficiency alleviates the symptoms you could experience with low iron and anemia. It also helps to prevent complications down the road as iron deficiency progresses to anemia.
Iron supplementation has no benefit in people who do not have an iron deficiency.
Iron supplementation is helpful for anemia caused by iron deficiency. There are several different causes of anemia, but iron deficiency is the most common. Anemia results when iron deficiency progresses to the point where it causes low levels of hemoglobin (a protein in red blood cells).
Iron deficiency can lead to arrhythmias, heart murmur, enlarged heart, and heart failure if left untreated. Iron deficiency may also be associated with an increased risk of fibromyalgia.
Iron supplementation can improve iron levels and treat IDA. Daily iron supplementation has been shown to reduce the prevalence of anemia and low iron status in menstruating individuals.
Iron deficiency is the most common nutrient deficiency. Left untreated, it can lead to numerous health issues. If you suspect you may be deficient, discuss with your healthcare provider so that a deficiency can be appropriately confirmed and treated.
Iron may help manage unexplained fatigue, even in someone who isn’t anemic but has a low ferritin level (an indicator of iron stores). This is especially common in women during their reproductive years. Daily iron supplementation may reduce fatigue in people who have periods.
The authors of a 2018 review concluded that iron supplementation reduced fatigue in people with iron deficiency non-anemia (IDNA). They also noted that eating iron-rich foods or iron supplementation should be considered as a treatment option to improve symptoms of fatigue even without diagnosed anemia.
A randomized trial studied females aged 18 to 53 who reported experiencing fatigue. Women with ferritin less than 50 micrograms per liter (mcg/L) and hemoglobin greater than 12 grams per deciliter randomly received either 80 milligrams (mg) of elemental iron or placebo. The group receiving iron reported greater improvement in fatigue but no improvement in overall quality of life.
If you have low ferritin levels, iron supplements may improve fatigue and help increase your energy.
Iron supplementation may improve fatigue in women with low ferritin levels.
Iron is needed to make myoglobin, the protein that provides oxygen to the muscles. Many athletes may have inadequate iron intake from their diet to support performance.
However, athletes involved in endurance training, such as marathon running or endurance cycling events, can lose more iron. Additionally, being female or vegetarian can put an athlete at a higher risk for iron deficiency and anemia. Athletes should make sure their diet includes enough iron to support peak performance.
Daily iron supplementation in menstruating people helped improve exercise performance in one study. It has also been shown to improve maximal and submaximal exercise performance in females of reproductive age.
Female athletes of reproductive age are at risk of iron deficiency. Iron supplementation has shown improved athletic performance in this group.
Restless leg syndrome is a health condition in which people have an uncontrollable urge to move their legs. This usually occurs at night and can disrupt sleep.
A systematic review and meta-analysis published in 2019 concluded that iron supplementation improved the International Restless Leg Syndrome score (IRLSS) after four weeks.
Research shows that cognitive levels drop with iron deficiency. In fact, when iron levels in the blood drop, concentration and attentiveness are affected almost immediately. Restoring iron levels to a normal range can improve concentration and boost cognitive performance.
Cognitive impairments in people with iron deficiency include deficits in attention span, intelligence, and sensory perception functions. Emotions and behavior may also be affected.
Hair loss can be the result of an iron deficiency. There is some evidence that raising the storage of iron ferritin in people with iron deficiency may improve hair loss. This can be done through iron replacement therapy. However, more research is needed to understand better how iron and hair growth are related.
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Iron deficiency is one of the most common nutrient deficiencies. Iron deficiency progresses through phases, ultimately resulting in IDA:
The phases of iron deficiency are as follows:
Iron deficiency results from either excessive losses of iron or too little iron in the diet.
Losses may occur through blood loss, reduced absorption, or prolonged exercise (e.g., athletes who compete in marathon running or cycling endurance events). For example:
People with conditions affecting the gastrointestinal (GI) tract or a history of surgeries on the GI tract are at risk of IDA. For example:
Following a vegetarian diet long-term may also cause an iron deficiency because plant-based sources of iron do not get absorbed, and animal sources do not.
Some people may be more likely to develop an iron deficiency than others. The risk of developing an iron deficiency is greater in:
Iron deficiency is almost 25% in people who underwent a Roux-en-Y gastric bypass and about 12% in people who've had a gastric sleeve procedure.
Iron deficiency also occurs in many health conditions, such as:
Long-term use of antacids may also put you at a greater risk.
Symptoms of iron deficiency include the following:
Discuss your symptoms with your healthcare provider if you suspect you have an iron deficiency. A complete blood count (CBC) will include a hematocrit and hemoglobin level. Low levels of hemoglobin suggest anemia. Your healthcare provider may perform additional tests to determine if an iron deficiency is causing the anemia.
A serum ferritin test is the preferred blood test for diagnosing iron deficiency. It can identify low levels of iron before it progresses to IDA. Generally, serum ferritin of less than 30 micrograms per liter (mcg/L) suggests iron deficiency, and a level of less than ten micrograms per liter suggests IDA.
The World Health Organization (WHO) issues recommended cutoff values to indicate iron deficiency:
| Recommended cutoff | |
|---|---|
| Children under the age of 5 years | Less than 12 micrograms per liter |
| Children 5 years and older and adults | Less than 15 micrograms per liter |
| Children under 5 years with infection or inflammation | Less than 30 micrograms per liter |
| Children 5 years and older and adults with infection or inflammation | Less than 70 micrograms per liter |
Iron supplements can cause nausea, vomiting, and stomach pain.
Constipation is another common side effect of iron supplementation, so be sure to get enough fiber and water in your diet. If it continues to be problematic, ask your healthcare provider if adding a stool softener is appropriate for you.
The risk of iron overload from diet alone is minimal in most healthy adults. Most of the time, if there is more iron in the body than necessary, the body will save it for future use.
However, people with certain genetic disorders are at risk for iron overload if their conditions cause them to absorb more iron from food. Hemochromatosis is a genetic disorder in which iron builds up in the body. Iron supplementation is not recommended if you have hemochromatosis.
There are very rare cases of iron overdoses leading to internal bleeding, seizure, coma, and even death.
The most common side effect of iron supplementation is stomach upset and constipation. Adequate fiber and water in the diet may help constipation. Ask your healthcare provider if adding a stool softener is a good idea.
People with hemochromatosis should avoid iron supplementation. With this condition, iron can build up to dangerous levels in the body.
Keep iron supplements out of reach of children. There are several cases of accidental iron overdoses in children resulting in death. Iron supplements now have a warning label to inform caregivers of this danger.
The recommended dietary allowance (RDA) for iron varies by age and gender:
During pregnancy, the requirement increases to 27 mg/day. For breastfeeding people, the requirement is 9 to 10 mg/day.
The tolerable upper limit (TUL) for iron is:
People who are generally healthy and not iron deficient should avoid supplements providing more than the TUL for iron.
For treating iron deficiency, 50 to 100 mg/day of iron divided into two to three doses is frequently recommended. Follow your healthcare provider's guidance for iron supplementation to treat a deficiency.
Iron supplements should be taken with food. Some claims suggest that taking iron with vitamin C can help with absorption. However, a 2020 trial suggests this may not be the case. The trial, which included people with an iron deficiency, found no difference in hemoglobin and serum ferritin between those who took iron with vitamin C or iron alone.
Unless you are deficient in iron, you should limit your total iron intake to no more than 45 milligrams daily. Those who are iron deficient should discuss iron supplementation with their healthcare provider.
There is minimal risk of developing iron overload from your diet alone.
Taking too much iron from supplements can lead to stomach upset and constipation. Excess iron can cause toxicity, inflammation of the stomach lining, and ulcers. The buildup of iron levels in the body can eventually lead to cirrhosis, liver cancer, and heart disease. Taking iron supplements may also reduce zinc absorption.
In severe cases, iron overdoses (taking 60 mg/kilograms body weight) resulted in organ failure, coma, and death.
It is important to know that iron poisoning can occur in children, potentially causing severe injury or death. Iron poisoning can occur if young children accidentally ingest adult iron capsules or pills. To prevent this, keep supplements out of children's reach and keep them in child-proof containers. Seek medical attention if you think your child may have taken adult iron pills.
Iron supplements may interact with several medications, including the following:
Antacids reduce the acidity in the stomach that is needed for iron absorption. Those taking antacids long-term are at risk of developing iron deficiency. Your healthcare provider may suggest you take iron supplements two to four hours before or after antacid medications.
Certain foods can reduce how well iron is absorbed in the body, including the following:
Iron supplements may reduce the absorption of other key micronutrients, including zinc, copper, magnesium, and manganese.
Calcium may interfere with iron absorption. Take iron and calcium supplements at different times of the day.
It is best to read the labels for how to store iron, as supplements contain many different forms of iron.
Iron toxicity is a leading cause of death due to poisoning in young children. Keep all iron supplements out of reach of children and pets, preferably in a locked cabinet.
Iron is readily available in the diet. Iron in foods comes in two different forms: heme and nonheme.
Heme iron tends to be better absorbed. Eating sources of heme iron generally boosts your iron levels a lot more than eating sources of nonheme iron. However, foods with nonheme iron are still part of a well-balanced, nutritious diet, so don't skip out on them.
Heme iron is commonly found in meat, seafood, and poultry. Sources of heme iron include the following:
| Meat and Eggs | Seafood |
|---|---|
| Beef | Shrimp |
| Lamb | Clams |
| Ham | Scallops |
| Turkey | Oysters |
| Chicken | Tuna |
| Veal | Sardines |
| Pork | Haddock |
| Liver | Mackerel |
| Eggs (any style) |
Nonheme iron is found in fruits, vegetables, and nuts. The following plant-based foods are good sources of nonheme iron:
| Vegetables | Fruit | Bread and Cereals | Beans and Other Foods |
|---|---|---|---|
| Spinach | Strawberries | White bread (enriched) | Tofu |
| Sweet potatoes | Watermelon | Whole wheat bread | Beans (kidney, garbanzo, or white, canned) |
| Peas | Raisins | Enriched pasta | Tomato products (such as paste) |
| Broccoli | Dates | Wheat products | Dried peas |
| String beans | Figs | Bran cereals | Dried beans |
| Beet greens | Prunes | Corn meal | Lentils |
| Dandelion greens | Prune juice | Oat meal | Instant breakfast |
| Collards | Dried apricots | Cream of Wheat | Corn syrup |
| Kale | Dried peaches | Rye bread | Maple syrup |
| Chard | Enriched rice | Molasses |
In the United States, wheat and some other flours are fortified with iron. Breakfast cereals are also fortified with iron at 18 milligrams per serving and may be able to meet iron requirements alone.
For infants, breastmilk has enough iron until they reach 6 months of age. After that, the introduction of foods provides additional iron. Infant formulas are often fortified with 12 mg per liter of iron.
Additionally, cooking on cast iron can also help you add more iron to your diet.
Iron supplements come in many different forms, such as pills, gummies, chews, and liquids.
Most iron supplements provide iron as a compound, such as ferrous sulfate, ferrous gluconate, or ferrous succinate. Many iron tablets you'll find will have 325 mg of ferrous sulfate.
The amount of the compound in the supplement is not the same as the amount of iron in the supplement. For example, ferrous sulfate is only 20% iron. Therefore, 250 mg of ferrous sulfate provides 50 mg of elemental iron. The supplement facts on the label should indicate the amount of elemental iron so that you don't have to do any calculations.
So, is it reasonable to take iron every day? The answer depends on your personal iron needs. People with iron deficiency or anemia and those who donate blood often may benefit from taking iron supplements daily.
If you are taking iron supplements, it's important to have your iron levels monitored by a healthcare professional. Too much iron can be dangerous, leading to multisystem organ failure, coma, convulsions, and even death.
A medical professional can also give iron intravenously (in the vein). A one-time dose was more effective than oral supplementation for patients who underwent a Roux-en-Y gastric bypass.
Iron supplements are only recommended in cases of diagnosed deficiency or when someone is at high risk for a deficiency. If you think you have a deficiency, talk to your healthcare provider to confirm the true cause of your symptoms and get advice on proper treatment.
Iron is one of the most important minerals your body needs to remain healthy. If left untreated, iron deficiency can progress to anemia. Iron supplements are used to treat iron deficiency and IDA under medical supervision. There is almost no need to supplement iron if you are not iron deficient or anemic.
People without an iron deficiency can usually get the iron they need from their diet. If you do start iron supplementation on your own, avoid taking more than 45 milligrams daily (the TUL for iron) unless you are treating a deficiency or IDA.
The ideal iron supplement is one that provides the needed dose for you with minimal side effects. It should also be high quality, absorbed well, and a good value for the cost. Talk to your healthcare provider before starting any new supplements.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
By Jennifer Lefton, MS, RD/N, CNSC, FAND
Lefton is a registered dietitian/nutritionist and certified nutrition support clinician with over 20 years of experience in clinical nutrition.
