Iron Overload from Daily High-Dose Supplements: Why Most Men Do Not Need a 65 mg Tablet

Iron is the supplement most likely to cause real harm to someone who takes it without needing it. The harm shows up two ways: acute pediatric poisoning, which is well-recognized, and chronic iron loading in adults, which is not. The standard 65 mg ferrous sulfate tablet found in virtually every drugstore was designed for iron deficiency anemia in menstruating or pregnant women. For adult men without diagnosed deficiency, daily use produces a slow, asymptomatic accumulation with real downstream consequences.

Adult male iron physiology

The human body has no regulated mechanism for excreting iron. Total body iron is regulated almost entirely on the absorption side, by hepcidin, with daily losses of roughly 1 mg through sloughed cells and minor bleeding. Adult men have no regular blood loss and reach their adult iron stores by age 18–25; their iron requirement after that is roughly 1 mg/day, easily met by a normal omnivorous diet.

A 65 mg ferrous sulfate tablet (or even a 27 mg over-the-counter iron capsule) provides 5–20x physiological need. Even with hepcidin throttling, daily supplementation pushes net positive iron balance and over years drives up serum ferritin and tissue iron deposition. The progression from elevated ferritin to functional iron overload to cirrhosis or cardiomyopathy takes years to decades, but the trajectory is one-way in the absence of bleeding.

Who benefits and who is harmed

Iron supplementation is indicated in diagnosed iron deficiency (low ferritin with or without anemia), in pregnancy, in chronic blood loss (menorrhagia, GI bleeding, frequent blood donation), and in malabsorption (celiac disease, bariatric surgery, autoimmune gastritis). Most premenopausal women fall into one of those categories with reasonable frequency.

Adult men without a documented indication should not take routine iron supplements. The number of men in the US taking daily multivitamins that include 18–27 mg of iron is in the tens of millions; this is not the largest health threat in their lives, but it is a slow, avoidable one. The same logic applies to postmenopausal women without ongoing blood loss. The HEIRS trial showed asymptomatic adult iron overload is more common than typically assumed, particularly in men of Northern European ancestry where HFE-related hereditary hemochromatosis affects roughly 1 in 200.

Practical screening and what to do

A simple serum ferritin and transferrin saturation panel at routine adult health visits identifies most cases. Ferritin above 300 ng/mL in men or 200 ng/mL in non-pregnant women, particularly with transferrin saturation above 45%, warrants stopping supplemental iron and investigating for hemochromatosis or other causes of iron loading. Inflammatory states elevate ferritin independently and need to be interpreted alongside CRP.

For men, the practical rule is: take an iron-containing multivitamin only with a documented reason. "Senior" formulations typically omit iron specifically because of this issue; men's formulations more variably do. Check the label. If you have been on daily iron for years without a clear indication, get a ferritin check before the next refill.

Bottom line

Iron supplementation outside of a documented indication slowly loads iron in adult men and postmenopausal women, with no benefit and meaningful long-term harm. Men taking iron-containing multivitamins should switch to an iron-free formulation unless their clinician has documented deficiency. Hereditary hemochromatosis is common enough that periodic ferritin screening in adults is a low-cost, high-yield intervention.