Iron deficiency affects far more people than previously thought. A recent study uncovered that 14% of U.S. adults suffer from absolute iron deficiency, meaning their bodies lack adequate iron. Another striking finding is that 15% of adults have functional iron deficiency, where their bodies are unable to properly utilize the iron they have.

The researchers made these interesting findings using a nationally representative survey of 8021 U.S. adults between 2017 and 2020. The participants were non-institutionalized civilian men and women aged 18 or older who had available measurements for serum ferritin, iron, and unsaturated iron-binding capacity.

The study estimated the prevalence of both absolute and functional iron deficiency among all U.S. adults, as well as separately for men and women by age group. Absolute iron deficiency was defined as having serum ferritin levels below 30 ng/mL, regardless of transferrin saturation. Functional iron deficiency was defined as having serum ferritin levels of 30 ng/mL or higher, with transferrin saturation below 20%.

"These findings suggest that absolute and functional iron deficiency affects a large proportion of American adults even in the absence of anemia, heart failure, or chronic kidney disease. Further research on the role of functional iron deficiency in adverse health outcomes and on iron deficiency screening strategies is needed," the researchers wrote in the journal Jama Network Open.

Iron deficiency is commonly seen in young children, adolescent girls, and women of childbearing age, as well as in individuals with anemia, chronic kidney disease, and heart failure. However, its prevalence outside these groups remains unclear.

"This is a common yet underappreciated public health problem. What's unique about our study is we were looking at regular people who would not otherwise have been screened or tested," said study co-author Leo Buckley, a clinical pharmacology specialist at Brigham and Women's Hospital in Boston.

Here's how to detect iron deficiency:

The best way to detect iron deficiency is through blood tests that measure iron, transferrin (the protein that carries iron), and ferritin (the protein that stores iron) levels in your blood.

When the iron levels are low, the body may not show any signs but as iron deficiency and resulting anemia worsen, people may experience fatigue, chills, shortness of breath, weakness, and dizziness. Some people have complaints of chest pain, difficulty concentrating, or frequent bruising. Anemia can also cause headaches, restless legs syndrome, and, in some cases, pica, a condition where individuals crave non-food items like ice, chalk, or clay. Other signs of iron deficiency anemia include pale skin, cold feet, and hands, brittle nails, and cracks at the corner of the mouth.

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