Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/1997
Publication Date: N/A
Interpretive Summary: Iron deficiency is one of the most common nutritional disorders in people, particularly in women and children who regularly consume diets that lack adequate amounts of iron. This debilitating disorder can be prevented by consuming supplemental doses of iron, but the most useful rate at which to take iron supplements has not been firmly established. The present study, in which rats were used as a model to study iron nutrition, was conducted to evaluate the influence of the frequency of iron supplementation on the efficiency of iron absorption. Animals fed four small doses of iron per day absorbed iron more efficiently than did animals fed a single daily dose of the same amount of iron; however, iron absorption efficiency was the highest in animals provided supplemental iron at a rate timed to coincide with the interval (about every three days) that approximated the lifetime of the cells lining the intestinal tract. These results suggest that supplemental iron may be utilized more effectively when it is consumed on an intermittent or alternate basis rather than when consumed on a consecutive or daily basis. Better understanding of the optimal frequency at which it is necessary to consume dietary supplements should lead to improved nutritional health of those at risk.
Technical Abstract: It is believed that frequent iron doses decrease the efficiency of iron absorption as a consequence of the loading of intestinal mucosal cells with iron from the previous supplemental dose. We examined this premise in 30 anemic Sprague-Dawley rats that were given iron supplements as 1-g preparations of ferrous sulfate in a 50:50 mixture of low-iron diet and sucrose under one of the following regimens: one 3-mg iron dose daily for three days, four 0.75-mg doses daily at six-hour intervals for three days, and one 9-mg dose on day 1 followed by two placebo (low-iron diet) doses on days 2 and 3. All groups were fed two low-iron meals daily (8.3 mg Fe/kg diet). After the rats were denied food overnight, they were dosed by gavage with 1 ml of an 59Fe-labeled ferric-nitrilotriacetic acid solution (37kBq 59Fe, 50 mu g Fe) and then killed 10 hours later. Absorption of 59Fe was measured as the proportion of the 59Fe retained by the carcass without the gastrointestinal tract. Also, hemoglobin iron gain, liver non heme iron and mucosal duodenal ferritin were determined. Rats provided either single or multiple doses of iron daily absorbed considerably less 59Fe from the test solution than did rats provided one iron supplement three days prior to assessment iron absorption. This suggests that supplemental iron may be utilized more effectively when it is consumed on an intermittent or alternate basis rather than when consumed on a consecutive or daily basis.