What Should You Do If You Suspect Iron Deficiency?
Ask your doctor for a complete iron panel including serum ferritin, serum iron, TIBC, and transferrin saturation — not just a hemoglobin test. Iron deficiency causes symptoms long before anemia develops. If confirmed, start iron-rich dietary changes and supplementation as directed. Investigate the underlying cause, especially heavy menstrual bleeding.
Ferritin is the most important test for detecting early iron deficiency. A common clinical error is checking only hemoglobin, which remains normal until iron stores are severely depleted. The WHO defines iron deficiency as ferritin below 15 ng/mL, but many experts use a cutoff of 30 ng/mL for diagnosing iron deficiency and 50 ng/mL for optimal stores, particularly in symptomatic women. A systematic review found that iron supplementation improved fatigue in women with ferritin below 50 ng/mL even without anemia.
Treatment of iron deficiency includes both oral supplementation and addressing the underlying cause. For premenopausal women, menstrual blood loss assessment is essential — heavy menstrual bleeding should prompt evaluation for uterine fibroids, endometrial polyps, adenomyosis, or bleeding disorders such as von Willebrand disease (which affects up to 1% of women). For postmenopausal women or men with iron deficiency, gastrointestinal evaluation is recommended to rule out celiac disease, peptic ulcer disease, or colorectal malignancy.
A systematic review found iron supplementation improved fatigue in women with ferritin below 50 ng/mL even without anemia
Why Are Women More Prone to Iron Deficiency?
Women need 18 mg of iron daily during reproductive years compared to 8 mg for men, primarily due to menstrual blood losses. Pregnancy requires 27 mg daily. Additional factors include lower dietary iron intake, vegetarian/vegan diets, dieting and caloric restriction, and reduced absorption from calcium and tannin-rich beverages consumed more frequently by women.
Menstrual blood loss is the primary driver of iron deficiency in premenopausal women. The average menstrual cycle results in 30-40 mL of blood loss, containing approximately 15-20 mg of iron. Women with heavy menstrual bleeding lose significantly more. The World Health Organization estimates that 30% of reproductive-age women globally are anemic, with iron deficiency as the leading cause. In developed countries, approximately 10-15% of premenopausal women are iron deficient.
Pregnancy dramatically increases iron requirements. Total iron needs during pregnancy approach 1,000 mg — 500 mg for expanded maternal red blood cell mass, 300 mg for the fetus and placenta, and 200 mg for normal daily losses. Without supplementation, most women cannot meet these needs through diet alone, which is why prenatal vitamins with 27 mg iron are universally recommended. Postpartum blood loss during delivery (average 500 mL for vaginal delivery, 1,000 mL for cesarean) further depletes iron stores.
How Can You Increase Iron Through Diet?
Eat heme iron sources (red meat, organ meats, poultry, shellfish) which are absorbed 15-35%, and non-heme sources (legumes, spinach, fortified cereals, tofu) absorbed at 2-20%. Pair non-heme iron with vitamin C-rich foods to boost absorption 2-3 fold. Avoid drinking tea or coffee with meals, as tannins reduce iron absorption by up to 60%.
Heme iron from animal sources is the most efficiently absorbed form. A 3-ounce serving of beef provides approximately 2.5 mg of highly bioavailable iron. Organ meats are particularly rich — beef liver contains 5 mg per 3-ounce serving. Dark meat poultry, oysters, clams, and sardines are other excellent sources. For vegetarians and vegans, lentils (6.6 mg per cup cooked), chickpeas (4.7 mg per cup), spinach (6.4 mg per cup cooked), fortified cereals, and tofu are the best plant-based sources.
Iron absorption is significantly affected by dietary factors consumed at the same meal. Vitamin C enhances non-heme iron absorption 2-3 fold — pairing iron-rich foods with citrus fruits, bell peppers, strawberries, or tomatoes is an effective strategy. Conversely, calcium inhibits both heme and non-heme iron absorption, so calcium supplements and dairy should be consumed at different meals than iron-rich foods. Tannins in tea and coffee reduce absorption by 60% — wait at least 1 hour before or after iron-rich meals before drinking these beverages.
