Forty-five apparently healthy women aged 35–45 years were
randomly assigned to three Fe absorption sub-studies (15 in each
one). The participants were not taking any medication or vitamins
or mineral supplements two months prior to or during the study.
None of the participants were blood donors, pregnant or lactating,
and all of them were using intrauterine devices or other contraceptive
methods at the time of the study. Pregnancy was ruled out
using a test for human chorionic gonadotropin in urine. Subjects
were characterized by age, weight, height, body mass index and
Fe status (biomarkers are described in Section 2.6).