CHANGES IN MEAL FREQUENCY ALTER IRON ABSORPTION EFFICIENCY IN RATS

Authors: BENITO, PALOMA - CORNELL UNIVERSITY; House, William; MILLER, DENNIS - CORNELL UNIVERSITY

Submitted to: Nutrition Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: The ability to absorb iron from the diet has been studied extensively because iron deficiency is a common nutritional disorder in women and children. Absorption of iron is influenced by iron stores in the body and the amount and form of dietary iron. In order to better explain results of studies to determine how much of the iron in the diet is available to be absorbed, it is necessary to understand how the amount of iron consumed prior to testing affects the efficiency of iron absorption by the cells lining the digestive tract. Rats were used as a model to study iron nutrition and a study was conducted to determine if the extent to which intestinal cells were able to absorb iron was altered by the frequency at which the rats were fed meals before the iron absorption test. Rats fed four meals daily absorbed more iron than did animals fed the same amount of iron in a single daily meal, but rats fed a single iron-containing meal for one day and then meals without iron for two days absorbed more iron than did rats in the other groups. These results showed that it was not just the amount of iron consumed prior to the absorption test but also the frequency of iron intake that altered the efficiency of iron absorption. Better understanding of steps regulating absorption of dietary iron will lead to improved methods to prevent or reduce the occurrence of iron deficiency anemia, a disorder that is common among some groups of people.

Technical Abstract: There is no standard procedure in regard to the type or feeding pattern of prestudy diet in studies on determinations of iron bioavailability. The objective of this study was to determine the influence of meal frequency on the absorptive capacity of mucosal cells. Male Wistar rats were assigned to three groups of ten rats each and fed 12 g of diet daily for three days. The food allotment was provided in either one meal (M1) daily (70 mg Fe/kg diet), four meals (M4) daily (70 mg Fe/kg diet), or a single meal for one day (210 mg Fe/kg diet) followed by single low-iron ls (9.4 mg Fe/kg diet) for two days (MX). The rats were then deprived of food for 18 hours, administered 59Fe by gavage, and then killed ten hours later. Absorption was estimated as 59Fe retained in the carcass without the gastrointestinal tract. Mucosal cells from the duodenum were isolated by mechanical vibration and mucosal ferritin determined by an immunoassay method. The effect of meal frequency on absorption efficiency of 59Fe was significant and independent of liver iron stores. Absorption of 59Fe dose was higher in rats fed four meals daily (mean = 42.2% of dose) than in those fed one meal daily (27.1%), but rats fed a single meal for one day then iron-deficient meals for two days absorbed significantly more 59Fe (64.8%) than did rats in the other groups. These data indicate that the frequency of iron consumed in a short-term period alter the efficiency of iron absorption in rats. Iron status of mucosal cells alone, as determined by mucosal ferritin, cannot explain the variations in iron absorption.