Red blood cells to highlight connection between blood and iron deficiency

What causes iron deficiency?

Medically reviewed on June 27, 2022 by Jordan Stachel, M.S., RDN, CPT. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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The body requires a constant supply of vitamins and minerals to function properly. These nutrients act as basic fuel and energy for the cells, but they also do everything from building new cells to regulating processes within organ systems.

One of the most important minerals that you need is iron. A lack of iron absorption in the body is known as an “iron deficiency.” Iron deficiency can contribute to some severe health issues, most prominently iron deficiency anemia. Iron deficiency is considered the world’s most common nutritional deficiency, and according to studies from Columbia University, about 30 percent of women and kids in the United States could have mild to severe forms of iron deficiency [1].

While it might seem like an easy fix, severe iron deficiency is more complicated than many people realize. Learn more about what causes iron deficiency, how to know if you have iron deficiency, and iron tests below.

What Is Iron?

Iron is a basic element that your body needs for general growth and development. Your body can’t synthesize iron on its own, so you generally get it from your iron rich diet or through iron supplements [2].

Iron serves a variety of different functions within the body. It’s a necessary component for certain hormones, for instance. Most prominently, iron is necessary for healthy red blood cells. The cells need iron to make the proteins hemoglobin and myoglobin. Hemoglobin is the protein in red blood cells that carries the oxygen from the lungs to the rest of the body. Myoglobin is the protein that delivers oxygen specifically to the muscles [2].

What Is Iron Deficiency Anemia?

When the body doesn’t have enough dietary iron to support hemoglobin production, the red blood cells suffer, resulting in anemia. Anemia refers to a condition wherein you lack the healthy red blood cells necessary to deliver oxygen and nutrients to the body’s organs and tissues. While there are several different types of anemia, iron deficiency anemia is the most common [3].

Iron deficiency anemia specifically comes from a lack of iron absorbed into the body. In its initial stages, iron deficiency anemia doesn’t present with any real symptoms, or the symptoms may be so mild that you might not notice them or mistake them for something else. As the chronic disease of anemia worsens and iron stores become even more depleted, you may experience:

  • Extreme physical fatigue
  • Weakness
  • Pale skin
  • Cold hands and feet (even in warm temperatures)
  • Breathing problems, fast heartbeat, and chest pain
  • Persistent headaches, dizziness, or lightheadedness
  • Inflammation in the tongue
  • Brittle hair and nails
  • A poor appetite
  • Sudden cravings for non-foods or non-nutritive substances, including ice, starch, or dirt

Left untreated, iron deficiency anemia can potentially lead to heart problems, including heart failure. It can also contribute to problems during pregnancy. In children, iron deficiency can delay basic growth and development and can increase susceptibility to infections [3].

The Causes of Iron Deficiency

You can be deficient in iron for a handful of different reasons.

Low-Iron Diet

This might seem like the most obvious reason, but it is also more complex than you think. Most people get enough iron from their diet, often without realizing it. The daily recommended amount of iron for adult men is about 8 mg, while adult women should get about 18 mg [2].

Iron is naturally found in certain foods, and many food manufacturers fortify their foods with iron. Iron-rich food options include:

  • Poultry, seafood, and meat
  • Spinach and other leafy greens
  • Nuts
  • Most legumes, like peas, white beans, kidney beans, and lentils
  • Some dried fruits
  • Breakfast cereals, breads, and other manufactured foods that are iron-fortified

The trick here is that iron comes in two forms: heme iron and nonheme iron. Nonheme iron is more common in plant-based foods, while most meats contain both heme and nonheme iron. Your body has more trouble absorbing nonheme iron. That’s not a problem if you are an omnivore, but if you are a vegetarian or vegan, you are mostly getting nonheme iron. Vegetarians and vegans are recommended to consume double their daily amount of iron to make up for the inefficient absorption of nonheme iron [2].

Problems Absorbing Iron

Even if you do get enough iron in the diet, you may have an underlying health problem that prevents proper absorption of the mineral. Iron from the diet gets absorbed into the body through the small intestines. This means that certain intestinal disorders can hamper the body’s ability to absorb nutrients from food. For example, celiac disease, characterized by damage to the intestinal lining when you eat gluten, can prevent absorption of iron and other nutrients. If you’ve had part of your intestines removed or bypassed via surgery, you may also have trouble absorbing enough iron [3].

Blood Loss

Considering most of your body’s iron is in your red blood cells, losing blood will naturally lead to losing iron. Women who experience heavy menstrual periods may have iron deficiency anemia. Slow, chronic blood loss within the body can also lead to iron deficiency. This can come from:

  • Peptic ulcers
  • Gastrointestinal bleeding
  • Colorectal cancer
  • Colon polyps
  • Hiatal hernias

If you are a frequent blood donor, you may have an increased risk of iron deficiency anemia.


The process of growing a fetus within the body takes a great deal of energy and nutrients provided by an expectant mother. During pregnancy, iron stores act as a source of hemoglobin for the developing fetus while also serving the increased blood volume of the woman’s own body. The daily recommended iron intake for pregnant women is at least 27 mg. Most pregnant women require an iron supplement to maintain that much iron intake [3].

Preventing Iron Deficiency

One of the best ways to prevent iron deficiency is to eat plenty of iron-rich foods. That includes eating plenty of meat, leafy greens, and legumes. As mentioned, if you are a vegetarian, you may need to increase your iron intake. You can also increase your body’s absorption of iron by consuming foods that are rich in vitamin C, which naturally helps to absorb dietary iron. Along with citrus fruits and juices, vitamin C is commonly found in:

  • Broccoli
  • Melons
  • Leafy greens
  • Peppers
  • Strawberries

You may need an iron supplement. However, don’t take an iron supplement unless you have talked to a healthcare provider about their recommendation as too much iron can be toxic. High levels of iron can interfere with zinc absorption and potentially contribute to organ failure and death. Iron may also interact with certain forms of medication, including some medication used to treat thyroid disorders [2].

8 Common Signs of an Iron Deficiency

What is Iron Deficiency Anemia?

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1. Are We Underestimating the Prevalence of Iron Deficiency? CUIMC. URL. Accessed June 27, 2022.

2. Iron. NIH. URL. Accessed June 27, 2022.

3. Iron deficiency anemia. Mayo Clinic. URL. Accessed June 27, 2022.

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