Ferric pyrophosphate (FePP) is a water-insoluble, food grade iron compound used to fortify rice, infant cereals and chocolate-drink powders as it causes no organoleptic changes to the food vehicle. However, it is only of low absorption in man. Therefore, strategies to enhance the bioavailability of FePP, such as adding citrate or decreasing the particle size of FePP need to be investigated. The primary objectives of the present study are: 1) to test whether the presence of citrate in iron fortified rice with FePP results in higher iron bioavailability, and 2) to test whether the presence of citrate in the rice grain during the extrusion and cooking process results in higher iron bioavailability compared with iron-fortified rice where citrate has been added shortly before consumption. As a secondary objective the investigators will compare the absorption from different FePP combinations with a reference meal fortified with ferrous sulphate. The investigator hypothesize that the addition of citrate enhances iron absorption and that the positive effect is greater when the citrate is added during the extrusion.

The investigator will conduct an iron absorption study in 20 women, 18 to 45 years old to evaluate the iron bioavailability from extruded rice fortified with 1) regular FePP, 2) regular FePP and citrate (both extruded into the rice kernels), 3) regular FePP and citrate added at the time of consumption, and 4) from normal rice fortified with ferrous sulphate at the time of consumption. Iron absorption will be measured as erythrocyte incorporation of stable iron isotopes at least 14 days after the administration of the isotopically labelled test meals. The iron absorption from the different meals within the same participant will be compared by repeated-measures ANOVA followed by a Bonferroni corrected pairwise comparison.

The present study will provide important data where iron bioavailability from rice is accurately and directly measured using stable isotopic labels as absorption tracers. This direct data can be used to base decisions on the level of fortification, can potentially reduce costs and optimize iron delivery to the targeted population in iron fortification programs.

Inclusion Criteria:

• Female, 18 to 45 years old
• Normal body Mass Index (18.5 - 25 kg/m2)
• Body weight < 65 kg
• Signed informed consent

Exclusion Criteria:

• Pregnancy (assessed by a pregnancy test)
• Lactating
• Any metabolic, gastrointestinal kidney or chronic disease such as diabetes, hepatitis, hypertension, cancer or cardiovascular diseases (according to the participants own statement)
• Continuous/long-term use of medication during the whole study (except for contraceptives)
• Consumption of mineral and vitamin supplements within 2 weeks prior to 1st meal administration
• Blood transfusion, blood donation or significant blood loss (accident, surgery) over the past 4 months
• Earlier participation in a study using Fe stable isotopes or participation in any clinical study within the last 30 days
• Participant who cannot be expected to comply with study protocol (e.g. not available on certain study appointments)