Don’t treat blood donation as a health habit: claims that it “detoxifies, lowers cholesterol, and prevents heart attacks” lack randomized trial support, while frequent donation truly causes iron deficiency

Cost: There is no monetary cost. A single donation — including registration, drawing blood, and post-donation observation — takes about an hour. Over the following weeks, the body works to replenish the lost iron.

In plain terms: The idea that donating blood helps “detoxify,” lowers cholesterol, or prevents heart attacks is not reliable. Those conclusions stem from observational data, and people who regularly donate are generally healthier to begin with. When this baseline difference is accounted for, the original claim that “each additional yearly donation lowers mortality by 18.6%” drops to just 7.5%. One actual randomized trial found no difference in death rates between donors and non-donors. On the other hand, donating too often does make people feel weak and cold — precisely because of iron loss.

Benefit: The Kuopio study in Finland followed 2862 men aged 42–60 for nearly nine years. In the 24 months prior to tracking, 153 men donated blood; only one (0.7%) suffered an acute heart attack. Among the remaining 2529 non-donors, 316 (12.5%) experienced the same outcome (P<0.0001). After adjusting for age and other coronary risk factors, donors showed an 88% lower risk of heart attack; the relative risk was 0.12 (95% CI 0.02–0.86, P=0.035). However, this result came from an observational study without randomization. The Nordic SCANDAT database included 1182495 donors observed over 9526627 person-years; 15401 deaths occurred. After controlling for age and gender, each extra yearly donation lowered mortality by 18.6% (95% CI 16.8%–20.4%). Once the fact that only healthy individuals are allowed to donate was factored in, the benefit fell to 7.5% (95% CI 5.7%–9.4%). Researchers concluded this does not constitute solid proof of health benefits. The FeAST randomized trial enrolled 1277 patients with symptomatic peripheral artery disease; one group received regular blood removal every six months to reduce iron levels, while the other served as a control. Overall mortality rates were 125 out of 636 (20%) versus 148 out of 641 (23%). HR 0.85 (95% CI 0.67–1.08, P=0.17). Combined outcomes of death, heart attack, and stroke also showed no significant difference: 180 out of 205 (28% vs 32%) with HR 0.88 (95% CI 0.72–1.07, P=0.20). The INTERVAL trial involved 45263 whole-blood donors divided into three groups based on donation intervals: 12 weeks, 10 weeks, or 8 weeks for men; 16 weeks, 14 weeks, or 12 weeks for women. Shorter intervals indeed yielded more blood within two years (the 8-week group produced 1.69 extra units compared to the 12-week group, 95% CI 1.59–1.80). Yet no differences emerged in quality of life, physical activity, or cognitive function. However, more donors reported fatigue, shortness of breath, dizziness, lightheadedness, and restless legs — especially at night. Average hemoglobin and ferritin levels also dropped, and more donations were postponed due to low hemoglobin (all P<0.0001). Iron deficiency impairs heat production: ten women with iron-deficiency anemia, eight with depleted iron stores but no anemia, and twelve controls were immersed in 28°C water for 100 minutes. The anemia group’s rectal temperature averaged 36.0±0.2°C versus 36.2±0.1°C in controls (P=0.001); oxygen consumption was 5.28±0.26 versus 5.99±0.29 mL·min⁻¹·kg⁻¹ (P=0.04). Thyroid hormones thyroxine and triiodothyronine were also lower (P<0.002). This pattern occurs because donors are repeatedly screened for good health; the hypothesis that “removing iron protects the heart” has not been confirmed in randomized trials.

Evidence grade: A

Sources: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. https://doi.org/10.1093/oxfordjournals.aje.a009669；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. https://doi.org/10.1111/trf.13205；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. https://doi.org/10.1001/jama.297.6.603；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. https://doi.org/10.1016/S0140-6736(17)31928-1；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. https://doi.org/10.1093/ajcn/52.5.813；全国人大常委会 (1997). 中华人民共和国献血法（第二、九、十四条）. https://flk.npc.gov.cn/detail?id=2c909fdd678bf17901678bf5e71801f9；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. https://www.gov.cn/zhengce/zhengceku/202401/content_6924875.htm

Notes: This entry does not oppose blood donation itself, but rather the notion that it serves as a personal health practice. Donated blood is used for others, and according to the beneficiary classification in this book, it falls under category 4, which refers to strangers. What actually benefits the donor is the policy-related perks. Article 14 of the Blood Donation Law stipulates that unpaid blood donors are exempt from fees related to blood collection, storage, separation, and testing when using blood services themselves; their spouses and direct relatives may also be exempt or receive fee reductions as specified by provincial governments. In January 2024, the National Health Commission announced that 55 provinces and regions have implemented policies allowing unpaid blood donors and their relatives to have such hospital fees waived directly at discharge. Those who receive the National Blood Donation Award are also eligible for local “three free” policies, which cover free public transport, free entry to government-run parks, and waived outpatient consultation fees at public hospitals. Donors should adhere to the legally mandated intervals: Article 9 of the Blood Donation Law states that each donation should be 200 milliliters at minimum and 400 milliliters at maximum, with at least six months between donations. The recommended age range for donation is 18–55 years. Do not shorten the interval merely to meet honor criteria or group targets. Women, those with lower body weight, and individuals with heavy menstrual flow already have limited iron reserves; regular donors may opt for a self-funded ferritin test. If persistent fatigue, cold intolerance, or restless legs at night occur after donation, these are not signs of “vital energy depletion” but likely due to iron deficiency; a blood test and ferritin check are advised, followed by iron supplementation and extended donation intervals as directed by a doctor. The evidence for cold intolerance specifically comes from a study involving just 2024 participants, and this figure is included here solely to illustrate the phenomenon, not to indicate how many people experience it.