Knowledge Related to Blood Donation and Iron, and Willingness to Take Iron Supplements Among Blood Donors in Multiple Countries

Frequent blood donation can deplete iron stores, increasing the risk of iron deficiency anemia. Postdonation iron supplements may help preserve donor health, but willingness to take supplements likely depends on donor knowledge and confidence. We conducted a cross-sectional survey among 5691 whole blood donors from 6 countries (Netherlands, USA, Japan, Finland, Sweden, Germany). Knowledge was assessed using 16 true-or-false statements on 4 blood donation-related topics; confidence by asking if donors were "certain" or "guessing." Willingness to take supplements was assessed using 3 scenarios: to continue donating, when advised by a donor physician, and general iron supplementation rejection. Using logistic regressions, we assessed associations between knowledge, confidence, and willingness to take iron supplements for each scenario, adjusted for sex, age, country, prior supplement use, and trust in the blood service. Most donors exhibited medium to high knowledge and under confidence in that knowledge. Willingness to take supplements was high (80.6%-84.2% across scenarios). Knowledge and confidence were not consistently associated with willingness to take supplements. In contrast, trust in the blood service (odds ratio [OR] = 1.64, P < .001) and prior supplement use (OR = 1.87, P < .001) were strongly associated with willingness when supplements were required to continue donating, with similar effects across other scenarios. Willingness varied across countries, with higher willingness in Nordic countries. These findings suggest that trust-building approaches may be more promising than education-focused strategies, though causal relationships require further research. High acceptance rates suggest that postdonation iron supplementation may be a feasible strategy for donor iron management.