Low-dose Iron Supplementation in Non-anaemic Iron-deficient Women

Inclusion Criteria: * informed consent as documented by signature * female gender * premenopausal * age \> 18 years * regular menstrual cycle * BMI in normal range (18-25 kg/m²) * serum-ferritin ≤30µg/l * no anaemia (Hemoglobin ≥117g/l) * no intake of dietary supplements containing iron (last 4 weeks) * the participant is linguistically and cognitively able to understand the study procedure Exclusion Criteria: * Current pregnancy * breastfeeding * hypermenorrhea (more than 5 unties/tampons per day) * chronic inflammatory diseases (e.g. colitis) * psychiatric disorders * chronic kidney disease (creatinine \>80 µmol/l) * liver disease (ALT \>35 U/l) * increased CRP (\>5mg/l) * hypersensitivity to iron-supplements * intake of medicines that interact with oral iron supplementation (e.g. PPI)