There are many possible causes of iron deficiency, from poor dietary intake to underlying health conditions. In this guide, we break down the most common reasons your iron levels may be low and what you can do about it.
Here are the key causes of iron deficiency you should know about:
Understanding the causes of iron deficiency is the first step toward getting the right treatment. Iron is an essential mineral your body cannot produce on its own. You get it through food, absorb it in your small intestine (a process that depends on healthy iron absorption), and use it primarily to make hemoglobin (the protein in red blood cells that carries oxygen throughout your body). Your body also stores iron as ferritin for future use.
When any part of this system breaks down, whether you are not eating enough iron, not absorbing it properly, losing it too quickly, or using more than usual, iron deficiency develops over time.
The most straightforward answer to what causes iron deficiency is simply not consuming enough iron rich foods. Red meat, poultry, seafood, beans, lentils, and leafy greens like spinach are primary sources. People following vegetarian or vegan diets are at higher risk because plant based (non heme) iron is absorbed less efficiently than animal based (heme) iron, according to the National Institutes of Health.
Even if you eat enough iron, your body may struggle to absorb it. Conditions like celiac disease, Crohn’s disease, and irritable bowel syndrome can all impair iron absorption in the small intestine. Gastric bypass surgery, which alters how the gut processes nutrients, is another major contributor. Certain medications (including proton pump inhibitors and antacids) can also reduce iron absorption significantly.
Blood contains red blood cells, and red blood cells contain iron. Any significant or ongoing blood loss depletes your iron stores over time. Heavy menstrual periods are one of the most common causes of iron deficiency in women of reproductive age. Internal bleeding from peptic ulcers, colon polyps, or colorectal cancer can also cause gradual iron loss. Regular blood donors may also experience lower iron levels.
During certain life stages, the body requires substantially more iron than usual. Pregnancy dramatically increases iron demand because the body must support the growing baby’s blood supply and fetal development. Infants and young children are at higher risk because iron requirements are high during rapid growth phases. Adolescents going through growth spurts similarly need more iron than their diet may provide.
Chronic conditions, including autoimmune disorders, kidney disease, and heart failure, can interfere with how the body handles and releases stored iron. This is sometimes called functional iron deficiency or anemia of chronic disease. In these cases, iron may be present in the body but is sequestered in a form that cannot be used for red blood cell production.
While iron deficiency can affect anyone, certain groups face significantly elevated risk. Women with heavy periods, pregnant or recently postpartum women, infants and toddlers, adolescents, vegetarians and vegans, people with gastrointestinal conditions like celiac disease or Crohn’s, those who have had gastric bypass surgery, frequent blood donors, and people with chronic inflammatory conditions are all at higher risk.
If you fall into one or more of these categories and experience fatigue, brain fog, shortness of breath, or hair loss, it is worth getting tested for iron deficiency.
Treating iron deficiency without addressing the cause is like filling a bucket with a hole in the bottom. At Flare MD, we do not just replenish your iron. We investigate why it is low in the first place. Depending on your history and iron deficiency labs, we may recommend dietary changes, further testing for absorption issues, evaluation for blood loss sources, or IV iron infusion to rebuild depleted stores quickly and effectively.
Stress alone does not directly deplete iron, but it can worsen absorption, disrupt eating habits, and exacerbate underlying conditions that contribute to iron loss. Chronic stress related inflammation can also interfere with iron metabolism over time.
Yes. Iron deficiency can develop despite a meat containing diet if blood loss is occurring, if you have an absorption problem, or if your iron demands have increased, such as during pregnancy. Diet is only one factor in what causes iron deficiency.
A complete blood panel including ferritin, serum iron, and TIBC (total iron binding capacity) can confirm deficiency. Finding the underlying cause may require additional tests, including a GI workup, hormone evaluation, or a review of current medications.
Coffee and tea contain tannins and polyphenols that reduce iron absorption when consumed alongside iron rich meals. While they do not cause deficiency on their own, drinking them with meals consistently can reduce how much iron your body absorbs over time.
