Don’t treat blood donation as health care: “detox, lower lipids, prevent heart attack” has no randomized-trial support; donating too often does cause iron deficiency

Claims that donating detoxifies, lowers lipids, or prevents heart attacks are unreliable. People who keep donating are already healthier; after subtracting that layer, the death-rate drop from one extra donation a year shrinks from nearly 20% to 7.5%. In trials that truly split people for comparison, death counts did not differ. On the flip side, donating too often does leave people weak and cold-sensitive — from iron deficiency.

Cost

No money. One donation — forms, the draw, plus staying to rest and be observed — takes about an hour. For weeks afterward the body keeps replacing the iron lost.

Benefit

The Finnish Kuopio study followed 2862 men aged 42 to 60 for nearly 9 years on average. Of 153 who had donated in the 24 months before counting started, 1 (0.7%) had an acute heart attack. Of 2529 who had not donated, 316 (12.5%) did (difference between the two rates P<0.0001). After subtracting age and other coronary risk factors, donors’ heart-attack risk was about 88% lower. Relative risk 0.12 (95% CI 0.02–0.86, P=0.035). But that is only from follow-up records, with no randomized comparison. The Nordic SCANDAT database has 1182495 donors followed for 9526627 person-years, with 15401 deaths. Subtracting only age and sex, one extra donation a year linked to 18.6% lower mortality (95% CI 16.8%–20.4%). Subtracting also the layer “only the healthy stay allowed to donate,” the drop is left at 7.5% (5.7%–9.4%). The authors conclude it “cannot be interpreted as solid evidence of a health benefit.” The FeAST randomized controlled trial enrolled 1277 people with symptomatic lower-limb arterial disease, randomized into two groups: one had blood drawn every 6 months to lower iron; one was a control. The main outcome was all-cause death: 125/636 (20%) versus 148/641 (23%). HR 0.85 (HR is a hazard ratio; 1 means the two sides match). 95% CI 0.67–1.08, P=0.17. Death plus non-fatal heart attack and stroke together: 180 (28%) versus 205 (32%), HR 0.88 (0.72–1.07, P=0.20). Neither showed a difference. The INTERVAL randomized trial enrolled 45263 whole-blood donors in three donation intervals: men 12, 10, or 8 weeks; women 16, 14, or 12 weeks. Shorter intervals clearly collected more blood over two years (men’s 8-week group 1.69 units more than the 12-week group, 95% CI 1.59–1.80). Quality of life, physical activity, and cognition showed no between-group differences. But donation-related discomfort rose, including fatigue, shortness of breath, vertigo, dizziness, and restless legs (legs so uncomfortable at night you cannot lie still). Mean hemoglobin and ferritin were also lower, and delays for low hemoglobin were more frequent (all P<0.0001). Iron deficiency affects heat production: 10 women with iron-deficiency anemia, 8 with exhausted iron stores but no anemia yet, and 12 control women sat in 28 °C water for 100 minutes. The anemia group’s rectal temperature was 36.0±0.2 °C versus 36.2±0.1 °C in controls (P=0.001). Oxygen use was 5.28±0.26 versus 5.99±0.29 mL·min⁻¹·kg⁻¹ (P=0.04). Thyroxine and triiodothyronine were also lower (P<0.002). The claim looks true because donors are already repeatedly screened healthy people, and the hypothesis “removing iron protects the heart” did not show up in randomized trials.

Notes

What to reject is “donate for your own body,” not donation itself. The blood is for others; by this book’s beneficiary tiers it sits in tier ④ (strangers). What can return to you is what the system provides. Article 14 of the Blood Donation Law says unpaid donors pay none of the collection, storage, separation, or testing fees when they use blood in hospital. Spouses and lineal relatives may be exempted or charged less under provincial rules. A January 2024 National Health Commission notice states that in 28 provinces unpaid donors and relatives already get those fees waived at discharge in provincial hospitals. Holders of the Voluntary Blood Donation Dedication Award may also, under local “three frees,” ride public transport free, enter government-run parks free, and skip ordinary outpatient consultation fees at public hospitals. Donate on the legal interval. Article 9 of the Blood Donation Law says each session is generally 200 mL, at most 400 mL. Intervals are no less than 6 months. The encouraged age is 18 to 55. Do not compress the interval to chase honors or group quotas. Women, people with low body weight, and people with heavy periods already run tight on iron; frequent donors may pay privately for one ferritin check. If after donating you stay weak, cold-sensitive, or at night must move restless legs, do not guess “vital energy was harmed” — get a blood count and ferritin. If iron deficiency is found, supplement as the doctor says and lengthen the donation interval. The cold-sensitivity human evidence is only 10 people; it explains why it can happen, not how many people it happens to.

Sources · 7

1. Salonen JT, Tuomainen TP, Salonen R, Lakka TA, Nyyssönen K (1998). Donation of blood is associated with reduced risk of myocardial infarction. The Kuopio Ischaemic Heart Disease Risk Factor Study. American Journal of Epidemiology, 148(5), 445-451. doi.org/10.1093/oxfordjournals.aje.a009669
2. Ullum H, Rostgaard K, Kamper-Jørgensen M, et al. (2015). Blood donation and blood donor mortality after adjustment for a healthy donor effect. Transfusion, 55(10), 2479-2485. doi.org/10.1111/trf.13205
3. Zacharski LR, Chow BK, Howes PS, et al. (2007). Reduction of iron stores and cardiovascular outcomes in patients with peripheral arterial disease: a randomized controlled trial. JAMA, 297(6), 603-610. doi.org/10.1001/jama.297.6.603
4. Di Angelantonio E, Thompson SG, Kaptoge S, et al. (2017). Efficiency and safety of varying the frequency of whole blood donation (INTERVAL): a randomised trial of 45 000 donors. Lancet, 390(10110), 2360-2371. doi.org/10.1016/S0140-6736(17)31928-1
5. Beard JL, Borel MJ, Derr J (1990). Impaired thermoregulation and thyroid function in iron-deficiency anemia. American Journal of Clinical Nutrition, 52(5), 813-819. doi.org/10.1093/ajcn/52.5.813
6. 全国人大常委会 (1997). 中华人民共和国献血法（第二、九、十四条）. flk.npc.gov.cn/detail?id=2c909fdd678bf1790167…
7. 国家卫生健康委等 (2024-01-08). 关于进一步做好无偿献血者激励奖励工作的通知. gov.cn/zhengce/zhengceku/202401/content_69248…