Submitted to: Nutrition Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/1997
Publication Date: N/A
Interpretive Summary: The number of meals eaten daily by people varies considerably, and the influence of going without food, or fasting, for short periods of time on the absorption of many nutrients, including iron, is not known. The present study, in which rats were used to study iron nutrition, was conducted to determine if absorption of dietary iron is affected by the number of meals eaten daily. This study showed that meal frequency affected iron absorption when dietary iron was provided as an available salt administered in meals fed to the rats. Those animals fed either four or two small meals daily absorbed and utilized the iron in the diet more efficiently than did animals fed one meal daily. Because iron absorption was affected by the number of meals eaten daily, the pattern of eating is a factor that should be considered in studies to assess the absorption of dietary iron. Increased understanding of factors that either promote or inhibit absorption of dietary iron will lead to improved methods to preven or reduce the occurrence iron deficiency, a nutritional disorder that is common among some groups of people.
Technical Abstract: The effects of short periods of fasting, characteristic of a human eating pattern consisting of one, two, or four meals daily, on iron absorption were investigated in anemic rats by hemoglobin repletion assay. Sixty weanling rats were fed a low-iron diet (8 mg Fe/kg diet) for 13 days. The anemic rats were then fed iron (FeSO4 or FePO4) fortified diets (35 mg Fe/kg diet) for 11 days under three feeding regimens: one, two, or four meals daily. Hemoglobin regeneration efficiency (hemoglobin gain/Fe intake) was the indicator of iron absorption. Greater hemoglobin regeneration efficiency was found in rats fed a FeSO4 diet with four (82.5+/-4.8%) or two (78.8+/-4.1%) meals daily than in rats pair-fed one (63.4 +/- 3.4%) meal daily; differences among groups fed the FePO4 diet were not significant. Both iron source and meal frequency affected iron absorption but the interaction effect was not significant. We conclude under the conditions of this study that fasting for as long as 24 hours does not enhance iron absorption and that the feeding pattern may be a factor to consider in studies to determine iron bioavailability.