Bioavailability of iron supplements consumed daily is not different from that of iron supplements consumed weekly.

摘要

This study was based on the hypothesis that prior administration of Fe produces a mucosal block to Fe absorption. A weekly dose schedule would allow the renewal of the Fe loaded enterocytes, presumably avoiding the Fe absorption blockade. The efficacy of a weekly vs. daily supplementation schedule on absolute Fe absorption was tested. Fe availability was measured in 3 groups of women. In group 1 (n=13) subjects received Fe 60 mg daily for 6 days and in group 2 (n=14) subjects received 120 mg every7 days for 3 weeks. In both groups the last 240 mg of Fe were radioisotopically labelled. In group 3 (n=14) subjects received 60 mg of radioisotopically labelled Fe before and after a daily supplementation with 60 mg of unlabelled Fe during 6 days. Geometric mean Fe absorption, standardized to 40% absorption of the reference dose of ferrous ascorbate, with daily (group 1) and weekly (group 2) dosages were 7.7 and 10.9%, respectively (unpaired Student t test). The corresponding values for Fe absorption before and after daily Fe supplementation (group 3) were 9.7 and 12.5%, respectively (paired Student t test). The total Fe absorption of the 240 mg of radioisotopically labelled Fe were 18.5 mg and 26.2 mg with daily (group 1) and weekly (group 2) Fe supplementation, respectively. It is concluded that these results do not support the Fe absorption blockade hypothesis. The demonstration that the absolute amount of Fe absorbed is similar in both daily and weekly schedules has practical implications for Fesupplementation programmes.