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The influence of previous iron intake on the estimation of bioavailability of Fe from a test meal given to rats
Published online by Cambridge University Press: 09 March 2007
Abstract
1. Iron retention and its subsequent distribution from 3 g 59Fe extrinsically-labelled wholewheat flour in rats given a low (8 μg Fe/g)- or high (566 μg Fe/g)-Fe diet during the previous 3 d was measured (Expt 1). The mean (with se) proportion of Fe retained from wholewheat flour was 0.46 (0.04) in the group given the low-Fe diet and 0.15 (0.01) in the group given the high-Fe diet (P < 0.001). There was no difference in distribution of absorbed 59Fe in the tissues examined.
2. The procedure was repeated in rats given diets containing a range of Fe concentrations, groups 1–6 respectively: 8, 77, 136, 334, 566, 1270 μg Fe/g (Expt 2). The mean (with se) proportions of Fe retained in groups 1–6 respectively were 0.60 (0.02), 0.34 (0.02), 0.30 (0.02), 0.20 (0.20), 0.17 (0.02), 0.09 (0.01). Regression analysis showed that Fe retention was a function of the logarithm of the Fe concentration of the diet consumed before the test meal (R -0.997, P < 0.0001) where Fe retained (μg) = 95–28 log10 Fe concentration of diet.
3. Rats were given a low-, medium- or high-Fe diet (8, 136 or 1270 μg Fe/g respectively) for 1 or 2 d instead of 3 d before measuring Fe retention from 3 g wholewheat flour (Expt 3). The mean (with se) proportions of Fe retained in rats given the low-, medium- or high-Fe diets for I d were 0.45 (0.02), 0.25 (0.02) and 0.13 (0.01) (P < 0.001) and for 2 d 0.47 (0.03), 0.31 (0.03) and 0.18 (0.02) (P < 0.001). There were no significant differences in Fe retention from animals given similar diets for 1 or 2 d before the test meal. As in Expt 2 regression analysis showed a highly-significant relationship between Fe retention and the logarithm of the previous dietary Fe concentration in both sets of groups.
4. It was concluded that the amount of Fe retained by rats from a 3 g meal of wholewheat flour depended on the previous dietary Fe intake. Only one meal in the previous 24 h was required to influence the ‘mucosal setting’ since there was no difference in response between rats preloaded for 1 or 2 d before the test meal.
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- Copyright © The Nutrition Society 1984
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