Iron Deficiency

Iron deficiency is one of the most common nutritional problems worldwide, affecting about one-third of the global population. When your body doesn’t have enough iron, it can’t produce adequate amounts of healthy red blood cells, leaving you feeling tired, weak, and short of breath.

Table of contents

• What is iron deficiency and why does it matter?
• How iron deficiency develops
• Signs and symptoms to watch for
• What causes iron deficiency?
• Who is most at risk?
• How doctors identify iron deficiency
• Treatment options
• How to prevent iron deficiency
• Possible complications

What is iron deficiency and why does it matter?

Iron deficiency occurs when your body’s iron stores are too low^[1]. Iron is a vital mineral that plays many important roles in keeping you healthy. Your body needs iron to make hemoglobin, which is a protein inside red blood cells that carries oxygen from your lungs to every part of your body^[1]. Without enough hemoglobin, your blood cannot deliver the oxygen your body needs to function properly^[1].

Iron also helps maintain a healthy immune system, supports muscle function, and is necessary for maintaining healthy cells, skin, hair, and nails^[2]. A special protein called myoglobin, which stores oxygen in muscle cells, also contains iron and gives muscles their red color^[3].

Your body is remarkably efficient at managing iron. When red blood cells can no longer function after about 120 days in circulation, they are absorbed by the spleen, and the iron from these old cells can be recycled^[2]. Iron is stored in the liver as ferritin and released as needed to make new red blood cells in the bone marrow^[2].

Iron deficiency is the most common nutritional disorder worldwide and affects approximately 25% of people globally^[4]. When iron deficiency becomes severe enough to reduce red blood cell production, it leads to iron deficiency anemia, which is the most common type of anemia^[1].

How iron deficiency develops

Iron deficiency doesn’t happen overnight. It develops gradually through three distinct stages as your body’s iron supplies become depleted^[1].

In the first stage, iron stores in your body decrease. At this point, your low iron supply hasn’t yet affected your red blood cells^[1]. You may not notice any symptoms during this stage.

During the second stage, when iron stores become low, your body changes the way it processes red blood cells. Your bone marrow begins making red blood cells without enough hemoglobin^[1]. You might start experiencing mild symptoms of iron deficiency during this phase.

In the third stage, hemoglobin drops below the normal range. This is when you develop signs of iron deficiency anemia^[1]. Symptoms become more noticeable and can significantly affect your daily life.

Signs and symptoms to watch for

Iron deficiency symptoms usually start out mild but worsen over time^[1]. Many people don’t realize they have iron deficiency because they simply feel tired and run down^[6].

Common symptoms include feeling fatigued, tired, listless, and weak^[6]. You may experience shortness of breath, dizziness, and lightheadedness^[1]. Some people notice they struggle to concentrate and remember things, or they perform poorly at school or work^[6].

Physical signs can include pale skin (in people with dark skin, paleness may be more evident in the whites of the eyes and on the palms)^[2], cold hands and feet^[1], and headaches^[1]. You might develop a sore or smooth tongue, and your fingernails and toenails may become spoon-shaped, a condition called koilonychia^[1]. Brittle nails and hair loss can also occur^[2].

Some people experience a rapid heartbeat or pounding in the ears, chest pain (especially with activity), muscle cramps, and irritability^[1][2]. A decreased interest in sexual activity and behavior problems have also been reported^[6].

One unusual symptom is pica, which is craving to eat substances that aren’t food, such as ice, dirt, paint, clay, or paper^[1][5]. If you experience cravings for ice or clay specifically, this is sometimes called “picophagia”^[2].

In children, iron deficiency can cause decreased appetite and increase the risk of developmental delays and behavioral disturbances^[18].

What causes iron deficiency?

Iron deficiency can develop for several reasons. The most common cause is blood loss, especially in older patients^[4]. Blood loss can occur from heavy menstrual periods in women or from gastrointestinal conditions like esophageal reflux disease, ulcerative colitis, or Crohn’s disease^[1].

Other sources of bleeding include gastritis (inflammation of the stomach), esophagitis (inflammation of the esophagus), ulcers in the stomach or bowel, hemorrhoids, and tumors in the digestive tract^[2]. Less common causes include chronic nosebleeds, blood loss from the kidneys or bladder, and frequent blood donations^[2].

Not getting enough iron in your diet is another cause, particularly if you follow a vegetarian or vegan diet^[1]. Iron from plant sources is not absorbed as well as iron from meat, poultry, and fish^[2].

Some health conditions cause problems with iron absorption. Malabsorption means iron can no longer be absorbed properly through your stomach^[1]. This is more common in people with celiac disease or those who’ve had weight loss surgery^[1]. People on anti-acid therapies or who have undergone bariatric procedures, especially gastric bypass operations, are also at risk^[2].

Sometimes your body’s need for iron increases beyond what you can get from food. This happens during pregnancy, when breastfeeding, and during periods of rapid growth such as infancy and adolescence^[4][6].

In developing countries, parasitic infestation is also a significant cause of iron deficiency^[4]. Children who drink more than 16 to 24 ounces a day of cow’s milk are at risk because cow’s milk contains little iron and can decrease iron absorption and irritate the intestinal lining, causing chronic blood loss^[2].

Who is most at risk?

Certain groups of people are more likely to develop iron deficiency. Women who menstruate are at greater risk than men and postmenopausal women, particularly if menstrual periods are heavy^[1][3]. On average, a menstruating woman loses approximately 1 mg of iron per cycle, though this can be as high as 5 mg or more with heavy bleeding^[18].

You’re more likely to develop iron deficiency if you are pregnant, have recently given birth, or are breastfeeding^[1][2]. Iron requirements during pregnancy are elevated to meet the needs of the developing fetus and placenta, and to account for blood loss during childbirth^[18].

Children are at risk due to increased demands from tissue and muscle growth^[18]. It’s thought that 9% of children ages 12 to 36 months are iron-deficient, and one-third of these children develop anemia^[4].

People who donate blood frequently are at increased risk^[1]. Those who have undergone major surgery, especially gastrointestinal or weight loss surgery, are also more vulnerable^[1][2].

People with gastrointestinal diseases such as celiac disease, inflammatory bowel diseases like ulcerative colitis or Crohn’s disease, peptic ulcer disease, or those on anti-acid therapies face higher risk^[2].

Vegetarians, vegans, and others whose diets don’t include iron-rich foods are at risk because iron from vegetables, even iron-rich ones, is not absorbed as well as iron from meat, poultry, and fish^[2]. Low-income families are particularly affected^[4].

Older adults are at increased risk, with rates between 12-17% for all adults over age 65^[18]. This can be due to renal disease and nutritional deficiencies^[18].

People who engage in vigorous exercise, particularly distance runners, may experience blood losses due to “foot strike” hemolysis. Increased sweating also results in iron losses, which may predispose adolescent female athletes to anemia^[18].

How doctors identify iron deficiency

Healthcare providers use blood tests to diagnose iron deficiency. Laboratory testing is necessary because symptoms alone cannot confirm the condition^[18].

A complete blood count (CBC) is typically the first test ordered^[2]. This test shows whether you have anemia by measuring your hemoglobin level and hematocrit, which is the percentage of blood volume made up by red blood cells^[15]. The test also measures the size and color of red blood cells. With iron deficiency, red blood cells are smaller and paler than usual^[15].

A serum ferritin test is the most accurate test to diagnose iron deficiency^[9]. Ferritin reflects iron stores in your body^[1]. A low level of ferritin most often means a low level of stored iron^[5]. Levels below 15 ng per mL are consistent with iron deficiency, but using a cutoff of 30 ng per mL improves detection while maintaining high accuracy^[9].

Additional tests may include measuring serum iron levels, total iron-binding capacity (TIBC), and transferrin^[1][2]. In someone with iron deficiency, these tests typically show low hemoglobin and hematocrit, low mean cellular volume (the average size of red blood cells), low ferritin, low serum iron, and high transferrin or TIBC^[2].

If bloodwork shows iron deficiency, more tests can help find the cause^[15]. Endoscopy can help check for bleeding from a hiatal hernia, an ulcer, or the stomach itself by passing a thin, lighted tube with a camera from the throat to the stomach^[15]. Colonoscopy can help rule out bleeding in the lower intestinal tract^[15]. People who have periods might have a pelvic ultrasound to look for causes of excessive bleeding during periods, such as uterine fibroids^[15].

Treatment options

The best treatment for iron deficiency depends on the cause, and you should talk to your doctor about your options^[6]. Treatment typically involves treating any disorder that’s causing bleeding, making sure your diet contains enough iron-rich foods, and taking iron supplements^[5].

Iron supplements are most often taken by mouth as pills or liquids for children^[5]. Of the various iron salts available, ferrous sulfate is the one most commonly used^[11]. The iron pills or liquid work best if you take them in the morning before eating, with orange juice or a vitamin C pill^[5]. This is because vitamin C helps your body absorb iron better^[16].

Treating iron deficiency with oral iron usually takes 3 to 6 weeks to work^[5]. However, you’ll usually keep taking iron for about 6 months to replace all the lost iron^[5]. Your doctor will do blood tests to make sure you’ve gotten enough iron^[5].

In some cases, iron may need to be given through a vein (intravenously), but this usually isn’t necessary^[5]. Intravenous iron therapy may be used in patients who cannot tolerate or absorb oral preparations^[11]. This approach is sometimes recommended when oral iron is contraindicated, ineffective, or not tolerated^[11].

It’s important to address any underlying health conditions that are causing the iron deficiency^[1]. Without treating the root cause, the deficiency will likely return.

Blood transfusions are rarely needed and should be reserved for patients with severe symptoms or circulatory compromise^[11].

How to prevent iron deficiency

Eating a diet that provides plenty of iron is the foundation of prevention^[16]. Good sources of iron include red meat, poultry, fish, and iron-fortified breakfast cereals^[3]. Organ meats (offal) are also rich in iron^[3].

The average person needs to absorb just a small amount of iron each day to stay healthy—around 1 mg for adult males and 1.5 mg for menstruating females^[3]. However, you need to consume several times that amount because your body absorbs only a fraction of the iron contained in the foods you eat^[3].

Some foods and drinks affect how much iron your body absorbs^[6]. Vitamin C-rich foods like oranges and lemons can help increase iron absorption^[12]. On the other hand, substances called polyphenols, found in foods like dark chocolate, red wine, berries, coffee, green tea, and turmeric, can bind to hemoglobin and inhibit iron absorption if consumed with iron-rich meals^[19]. If you are iron deficient, try having your iron-packed meals two hours after eating or drinking polyphenols^[19].

For babies, breastfeeding is protective against iron deficiency due to the higher bioavailability of iron in breast milk compared to cow’s milk^[4]. Babies need breast milk or iron-fortified formula in their first year^[6]. Babies who begin drinking cow’s milk in their first year are more likely to become iron deficient^[6].

If you’re in a high-risk group—such as being pregnant, breastfeeding, menstruating heavily, or following a vegetarian or vegan diet—talk to your doctor about whether you need iron supplements or dietary changes to prevent deficiency.

Possible complications

Severe or untreated iron deficiency can lead to serious complications^[1]. These include brain fog, which can make it difficult to think clearly and concentrate^[1].

In children, iron deficiency can cause growth or developmental delays^[1]. Young children with iron deficiency have an increased risk of developmental delays and behavioral disturbances^[18].

Heart conditions can develop, including enlarged heart or heart failure^[1]. This happens because when you’re anemic, your heart has to work harder to pump oxygen-rich blood throughout your body.

Some people develop restless legs syndrome, a condition that causes uncomfortable sensations in the legs and an urge to move them^[1].

Patients with iron deficiency have been found to have a longer hospital stay, along with a higher number of adverse events^[4]. This highlights the importance of early detection and treatment.