Iron absorption after introducing and discontinuation of iron and zinc supplementation in rats

The aim of this study was to investigate the changes in iron apparent absorption (IAA%) during and after iron and zinc supplementation in rats. The study was conducted on 6-week old male Wistar rats in 3 stages: 4-week period of adaptation to the control (C) and iron deficient (D) diets (stage I); 4-week period of supplementation with 10-time more iron (CSFe, DSFe), zinc (CSZn, DSZn) or both iron and zinc (CSFeZn, DSFeZn) compared to C diet (stage II); 2-week of post-supplementation period (rats were fed the same diets as in the adaptation period, stage III). IAA% was measured in five consecutive days directly after introducing and discontinuation of iron and zinc supplementation as well as in the end of stage II (days: 22-24th) and stage III (days: 8-10th). Overall in the second day after introducing and in the fifth day after discontinuation of iron or iron and zinc supplementation, the IAA% had undergone to the level compatible with the values in the end of each stage. At the end of stage II, IAA% in CSFeZn (54.1 ± 2.7%) rats was not different from the IAA% in CSFe rats (53.9 ± 1.9%), but in DSFeZn group IAA% (49.4 ± 2.1%) was significantly lower than in DSFe (57.4 ± 2.3%) group. Moreover, IAA% after stage II and stage III in DSZn group was significantly lower (39.2 ± 2.8% and 38.6 ± 2.6%, respectively) than in group D (60.7 ± 1.9% and 54.3 ± 3.0%, respectively). In conclusion, zinc administered simultaneously with iron (Zn:Fe weight ratio=1:1) decreased IAA% in adult rats fed on iron deficient diet, but not in rats fed on control diet. IAA% reduction by zinc supplementation has been extended to 10 days after discontinuation of the treatment. Adaptation of the rats to high doses of iron or iron and zinc and also to the cessation of these treatments was relatively fast. However, IAA% was stabilized faster after introducing the supplementation than it's discontinuation.