Conventional indirect indicators of iron status, using serum and red blood cell biomarkers, are confounded by inflammation from common infections and are therefore of limited use in populations carrying a high burden of infection and inflammation, as for example women of reproductive age in malaria endemic areas in developing countries. Even without the confounding effect of inflammation, current markers of iron status are insensitive to small changes in dietary iron and do not allow to establish associations between dietary, lifestyle and genetic factors and iron balance. With a new method based on the dilution of a previously administered and equilibrated stable isotope signal, an accurate measurement of long-term oral iron balance and absorption is possible, allowing the estimation of iron requirements and potentially providing fundamental guidance for supplementation and fortification programs in both healthy and chronically inflamed/infected patients. In the current study the novel methodology will be validated in generally healthy subjects with low iron status. The technique will be used to assess dietary and lifestyle determinants of iron status and to compare the effect on iron balance and iron status of three distinct, commonly used iron interventions: food fortification with iron; oral iron supplementation, and intravenous iron infusion.

Inclusion Criteria:

• Have participated in a former absorption study in our lab,
• Signed written informed consent to participate in the new study,
• Serum ferritin < 25 µg/L

Exclusion Criteria:

• Anaemia (Hb < 117 g/L),
• Any metabolic, gastrointestinal, kidney or chronic disease such as diabetes, renal failure, hepatic dysfunction, hepatitis, hypertension, cancer or cardiovascular diseases (according to the participants own statement),
• Allergic or similar reactions against iron supplements,
• Known fructose intolerance, glucose-galactose malabsorption or saccharase-isomaltase deficiency,
• Known hypersensitivity to ponceau R4 and ponceau R4 aluminium salt (E124)
• Continuous/long-term use of medication during the whole study (except for contraceptives),
• Regular consumption of mineral and vitamin supplements within 2 weeks prior to 1st supplement administration (more than 3 consecutive days or more than 5 times within 14 days),
• Blood transfusion, blood donation or significant blood loss (accident, surgery) over the past 6 months,
• pregnancy or breast feeding,
• Intention to become pregnant during the course of the study,
• Known or suspected non-compliance, drug or alcohol abuse,
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant,
• Participation in another study with investigational drug within the 30 days preceding and during the present study,
• Enrollment of the investigator, his/her family members, employees and other dependent persons