INFLUENCE OF IRON SUPPLEMENTATION FREQUENCY ON ABSORPTION EFFICIENCY AND MUCOSAL FERRITIN IN ANEMIC RATS

It is believed that frequent Fe doses decrease the efficiency of absor ption as a consequence of the loading of intestinal mucosal cells with Fe from the previous supplemental dose. We examined this premise in t hirty anaemic Sprague-Dawley rats given Fe supplements as FeSO4 in 1 g preparations of a 50:50 (w/w mixture of low-Fe diet and sucrose under one of the following regimens: one 3 mg Fe dose daily for 3 d, four 0 .75 mg doses daily at 6 h intervals for 3 d, and one 9 mg dose on day 1 followed by two placebo (low-Fe diet) doses on days 2 and 3. All gro ups were fed on two low-Fe meals daily (8.3 mg Fe/kg diet). After an o vernight fast rats were dosed with 1 ml of an Fe-59-labelled ferric ni trilotriacetic acid solution (3.7 kBq Fe-59, 50 mu g Fe) orally and ki lled 10 h later. Absorption of Fe-59 was measured as the percentage of the Fe-59 retained by the carcass without the gastrointestinal tract 10h after dosing relative to the initial Fe-59 dose. Haemoglobin-Fe ga in, liver non-haem-Fe, and mucosal duodenal ferritin were determined a fter the 30 supplementation period. Absorption of the test dose in rat s supplemented once 3 d before assessment of Fe absorption was 2.6-fol d greater than those supplemented with daily single doses and 1.9-fold greater than those supplemented with daily multiple doses. Our data i ndicate that both mucosal ferritin and liver Fe levels account for the higher absorption efficiency found in rats supplemented once to simul ate intermittent regimens.