Daily Iron Requirement

Recommended Daily Iron Intake

Iron does a lot of heavy lifting in the body. It's needed to build hemoglobin, to move oxygen around, and to keep oxidative metabolism running in the mitochondria. How much you need depends on your sex, age and where you are physiologically, which is what RDA = f(sex, age, pregnancy, lactation) is getting at. The NIH Office of Dietary Supplements puts the adult man at 8 mg/day and premenopausal women (19–50 y) at 18 mg/day, the higher figure reflecting menstrual losses. Pregnant women need 27 mg/day and women who are breastfeeding 9–10 mg/day.

How well you absorb iron swings a lot depending on where it comes from. Heme iron from red meat, poultry and fish gets taken up at 15–35%. Non-heme iron from beans, leafy greens and fortified cereals manages only 2–20%. Vitamin C (citrus, tomato) and animal protein help things along, while calcium, the polyphenols in coffee and tea, and phytates from whole grains work against you. Iron-deficiency anemia is still the most common micronutrient deficiency, both worldwide and here in Brazil.

Applications

It comes in handy for nutrition assessments, for planning vegetarian or vegan diets, for weighing up prenatal supplementation, and for following patients who have anemia or are losing blood chronically. In Brazil, the SUS hands out ferrous sulfate through the National Program for Iron Supplementation (PNSF) to pregnant women and children aged 6–24 months as part of primary care.

FAQ

Why do women need more iron than men? Each month, menstrual bleeding takes away 15–30 mg of iron, which is enough to more than double the daily requirement during the reproductive years.

Can I take iron with coffee or milk? Better not. Pairing iron-rich meals or supplements with coffee, tea or dairy lets tannins and calcium cut absorption by 40–60%. Take the supplement on an empty stomach, or alongside some vitamin C.

Is this a medical diagnosis? No. What the calculator gives you is a reference value. Diagnosing or treating iron deficiency takes lab work (ferritin, transferrin saturation, a hemogram) and a doctor's guidance.