Thesis Tiffany Timmer

Summary

Blood donors are prone to iron deficiency, as they lose approximately 250 mg of iron with every whole blood donation. Many European blood supply organizations have set selection criteria for donors, among which minimum hemoglobin (Hb) levels, in order to protect donor health (e.g. against iron efficiency) and blood product quality. Individual Hb levels are known to differ by factors such as sex, age and season, but less is known about the influence of lifestyle behaviors (i.e. dietary iron intake and physical activity) and genetic predisposition. Therefore, this thesis comprises epidemiological studies aimed at gaining insight into whether lifestyle behaviors and genetic factors are associated with iron and erythrocyte parameters in Dutch blood donors.
Most studies in this thesis used data from Donor InSight (DIS)-III (2015-2016), an observational cohort study including three groups of Dutch donors who participated in previous rounds of DIS, namely a group with (1) stable Hb trajectories, (2) declining Hb trajectories and (3) a randomly selected group. 
This thesis showed that heme iron intake has a positive impact on ferritin and Hb levels in a cohort representative of the Dutch donor population (DIS-III). One single nucleotide polymorphism (SNP), rs112016443 known to influence WDSUB1 gene expression, was associated with ferritin levels in our genome-wide association study using DIS-III data. A small number of SNPs in fourteen genes were repeatedly associated with erythrocyte parameters in previous population-based studies. These results provide starting points for further research on lifestyle behaviors and genetic factors in iron and erythrocyte parameters in blood donors.