Iron for Athletes, Heavy Periods and Blood Donors: Who Loses More Iron and What Is Advised

See a clinician first

Tiredness, breathlessness or weak performance have many causes, and iron deficiency is only one. The NHS says to see a GP if you think you might have iron deficiency anemia, and that a blood test is the usual first step. [1] Heavy periods that affect your life, last for some time or come with severe pain or bleeding between periods also need a GP. [2] Do not start iron tablets on a guess. Iron overdose is particularly dangerous for children; in the US call 911 or Poison Help at 1-800-222-1222 if a child may have swallowed iron. [3]

The short answer

Three groups lose iron faster or absorb it less well: people with heavy menstrual bleeding, endurance athletes, and frequent blood donors. MedlinePlus lists menstruating women (especially with heavy periods), long-distance runners and people who frequently donate blood among those at risk of a low iron level. [4] For all three groups the sources we read point the same way: test iron stores (ferritin and hemoglobin) before treating, find the cause, and let a clinician choose any treatment. [5][6]

Evidence labels used below: established nutritional role, promising but limited, mixed, and Proper evidence not found.

Heavy periods

The NHS says women who lose a lot of blood during their period are at higher risk of iron deficiency anemia and may need iron supplements, and to speak to a GP or registered dietitian. [7] It lists heavy periods and pregnancy as very common causes of iron deficiency anemia. [1] A 2023 review described heavy menstrual bleeding as highly prevalent and a major contributor to iron deficiency and iron-deficiency anemia, frequently normalized by society, health care providers and affected women themselves. [8] A 2025 JAMA review reported that in high-income countries about 38% of non-pregnant women of reproductive age have iron deficiency without anemia and about 13% have iron-deficiency anemia. [5]

The NHS notes heavy periods do not always need treatment, and that a series of blood tests may check for underlying conditions such as iron deficiency anemia. [2] Heavy bleeding can have its own causes that a clinician should look for; see Heavy or irregular periods and Women's health: when to get help.

Athletes

A narrative review found iron deficiency is most common in female athletes (roughly 15 to 35% of athlete cohorts) and also occurs in about 5 to 11% of male athlete cohorts. [9] Another review lists sweating, blood in the urine, gastrointestinal bleeding, inflammation and red-cell breakdown as ways iron is lost during exercise. [6] Exercise also raises hepcidin, described as the master iron regulatory hormone; one review says hepcidin peaks around 3 to 6 hours after exercise and limits absorption from the gut. [9][10] Common pain relievers such as ibuprofen and aspirin can cause stomach bleeding, a cause of iron loss the NHS names. [1]

What this does not show: that iron helps athletes with normal stores. In one small trial, 14 distance runners with ferritin 30 to 100 micrograms per liter received injected iron or saline; the authors reported better perceived fatigue and mood but no significant improvement in the 3,000 m time trial and no change in hemoglobin mass. [11] We did not retrieve a meta-analysis on iron supplements and performance in athletes with normal iron (searched PubMed), so for that question: Proper evidence not found. Reviews suggest assessing hemoglobin and ferritin in athletes at risk, with cut-offs that may need to differ by sex, age and sport. [6] More on active people is on Minerals for athletes and active people and Recovery after exercise.

Blood donors

A hematology review calculated that the iron removed in one whole-blood donation takes over 24 weeks to replace on a standard diet without supplements, and that repeated donation without enough replacement or a longer wait leads to iron deficiency. [12] Several trials looked at iron after donating. They gave study amounts, not advice:

We did not read a blood service's own donor iron policy (the Red Cross page refused access), so ask your donor center what it advises. Do not donate or supplement based on this page.

Testing and interpretation

Ferritin and hemoglobin are the usual starting measures. [6] A review says testing is indicated for people with anemia or symptoms, and should be considered for those with risk factors such as heavy menstrual bleeding. [5] The JAMA review defines iron deficiency as a low ferritin (typically under 30 ng/mL) in people without inflammatory conditions, so inflammation complicates interpretation, and ranges differ between laboratories. [5] See Iron tests explained and Iron deficiency and iron-deficiency anemia. Oral iron is first-line treatment for most patients, per the same review. [5] Intravenous options are on Iron infusions and prescription iron.