Blood donation

Donate because it helps others, not as a longevity treatment: roughly 3–4 times a year at most for men and 1–2 for premenopausal women, at least 12 weeks apart for men and 16 weeks for women, and get ferritin checked if you donate regularly.

What it does to your iron

The body has no regulated way to get rid of iron, so in adults who aren't losing blood, stores tend to creep up with age (see Iron and aging). Each donation removes iron with the blood, so donating reliably lowers stores and modestly offloads iron.

The mortality benefits claimed in donor studies are heavily confounded by the healthy donor effect. People have to be well to be accepted as donors and to keep donating, so donors would look healthier than average even if giving blood did nothing.

What it hasn't been shown to do

• Prevent heart attacks or extend life. The one large randomised test of lowering iron by removing blood, in people with peripheral artery disease, found no reduction in deaths or cardiovascular events.^[1] A pooled analysis of small studies in people with metabolic problems linked to high ferritin,^[2] and a small trial in donors with prediabetes,^[3] both from one research group, found slight improvements in insulin resistance on lab tests, but nobody has shown that this prevents diabetes, heart attacks or deaths. Bleeding toward deficiency has no benefit at all.
• Clear iron from the brain. In a small study of people with haemochromatosis, how often they had been bled poorly predicted how much iron sat in their deep brain regions,^[4] and whether donation changes brain iron in ordinary adults has not been tested.

How often to donate

The World Health Organization's minimum gaps between whole-blood donations are 12 weeks for men and 16 weeks for women, a precautionary minimum resting on low-certainty evidence.^[5] In a trial of about 45,000 English donors, donating more often than the UK standard (the same 12 and 16 weeks) lowered haemoglobin and ferritin and brought more tiredness, dizziness and deferrals for low haemoglobin.^[6]

Why regular donors need a ferritin check

Routine haemoglobin checks at donation don't catch falling iron stores. When Dutch donation centres began measuring ferritin and lengthening the gap to 6 months below 30 µg/L (12 months below 15 µg/L), the odds of iron deficiency among donors fell by about three-quarters in men and postmenopausal women and by about half in premenopausal women.^[7] Frequent donors are one of the groups most prone to iron deficiency, alongside premenopausal women, endurance athletes and long-term plant-based eaters.

What to do

1. Give blood if you can, for the people who receive it.
2. Keep to roughly 3–4 donations a year for men and 1–2 for premenopausal women, with at least 12 weeks between donations for men and 16 weeks for women.
3. Get ferritin checked if you donate regularly. Dutch centres wait 6 months when ferritin is below 30 µg/L and 12 months below 15 µg/L.
4. Don't use donation to treat diagnosed iron overload on your own. Haemochromatosis needs clinical management.

Further reading

• Di Angelantonio E et al. Efficiency and safety of varying the frequency of whole blood donation (INTERVAL): a randomised trial of 45 000 donors. Lancet 2017.^[8]
• Meulenbeld A et al. Effectiveness of ferritin-guided donation intervals in whole-blood donors in the Netherlands (FIND'EM): a stepped-wedge cluster-randomised trial. Lancet 2024.^[9]
• Severijns P et al. What is the impact of whole-blood donation frequency on donor health? A systematic review. Vox Sang 2026.^[10]
• Zacharski LR et al. Reduction of iron stores and cardiovascular outcomes in patients with peripheral arterial disease: a randomized controlled trial. JAMA 2007.^[11]