Iron deficiency is the world's most common nutritional deficiency, affecting an estimated 25% of the global population. In the US, it's most common in menstruating women, pregnant women, infants, and people with GI bleeding. Iron deficiency anemia develops when stored iron runs out and red blood cell production is impaired.
Common symptoms
Fatigue and decreased exercise tolerance
Pale skin, especially inside the lower eyelid
Shortness of breath with exertion
Cold hands and feet
Brittle or spoon-shaped nails
Hair thinning or hair loss
Restless legs syndrome (especially at night)
Pica — unusual cravings for ice, dirt, or starch
Headaches and lightheadedness
At-risk groups
Menstruating women, especially those with heavy periods
Pregnant women (iron requirements nearly double)
Infants and toddlers, especially those weaned to cow's milk early
Adolescents during growth spurts
Vegetarians and vegans (plant iron is less bioavailable than heme iron)
People with GI conditions causing chronic blood loss (ulcers, IBD, colon cancer)
Frequent blood donors
People who've had bariatric surgery
When to see a doctorPersistent fatigue with any combination of pale skin, shortness of breath, hair thinning, or unusual cravings warrants a CBC plus ferritin test. Important: do NOT begin iron supplementation without testing first — iron overload can cause organ damage, and iron supplements interact with many medications.