Benito P, House W, Miller D
Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA.
Br J Nutr. 1998 Jun;79(6):533-40. doi: 10.1079/bjn19980092.
To evaluate the extent to which daily oral Fe supplements may block Fe absorption from a subsequent dose, we compared effects of oral and intraperitoneal (i.p.) Fe supplementation on Fe status in anaemic rats (haemoglobin (Hb) 90 g/l). A ligated duodenal loop technique was used to assess the effects of the Fe supplements administered either orally or i.p. at different frequencies on Fe absorption from a subsequent test dose. Anaemic Sprague-Dawley rats were assigned to seven groups of eight rats each and received either oral or i.p. Fe supplements for 3 d as follows: (1) 4 mg oral supplement daily (three doses in 3 d); (2) 4 mg oral supplement once (one dose on day 1, low-Fe dose on days 2 and 3); (3) 12 mg oral supplement once (one dose on day 1, low-Fe dose on days 2 and 3); (4) 3.2 mg i.p. supplement daily (three doses in 3 d); (5) 3.2 mg i.p. supplement once (one dose on day 1); (6) 9.6 mg i.p. supplement once (one dose on day 1); (7) low-Fe diet (control). The effectiveness of the supplements in treating Fe deficiency on each of the two test-factors, i.e. route of administration and frequency of dose, was assessed by determining Hb-Fe gain and liver-Fe stores after the 3 d test period. Oral supplementation was as effective as i.p. in improving the Fe status of the anaemic animals. However, a 15 min absorption of a radio-Fe test dose from a ligated loop in i.p.-supplemented groups was significantly higher (11.68 (SD 1.70)%, 17.49 (SD 4.59)%, 16.71 (SD 3.39)%) than in orally supplemented groups (3.24 (SD 1.35)%, 2.45 (SD 1.05)%, 1.80 (SD 0.35)%) despite equal body Fe stores. No significant difference in intestinal Fe absorption efficiency was detected within the oral groups but those supplemented only once were more effective than or as effective as the group receiving daily supplements for 3 d in improving Fe status as indicated by Hb-regeneration efficiency. We conclude that there is a mucosal block with the administration of oral Fe supplements but the extent of this blocking effect during oral Fe supplementation is not as dramatic as currently thought in the context of the poor efficacy of daily Fe supplementation programmes.
为了评估每日口服铁补充剂可能阻断后续剂量铁吸收的程度，我们比较了口服和腹腔内（i.p.）补充铁对贫血大鼠（血红蛋白（Hb）90 g/l）铁状态的影响。采用结扎十二指肠袢技术评估不同给药频率的口服或腹腔内铁补充剂对后续测试剂量铁吸收的影响。将贫血的斯普拉格-道利大鼠分为七组，每组八只，按以下方式接受口服或腹腔内铁补充剂3天：（1）每日口服补充剂4 mg（3天内分三次给药）；（2）口服补充剂4 mg一次（第1天给药一次，第2天和第3天给予低铁剂量）；（3）口服补充剂12 mg一次（第1天给药一次，第2天和第3天给予低铁剂量）；（4）腹腔内补充剂3.2 mg每日（3天内分三次给药）；（5）腹腔内补充剂3.2 mg一次（第1天给药一次）；（6）腹腔内补充剂9.6 mg一次（第1天给药一次）；（7）低铁饮食（对照组）。通过在3天测试期后测定血红蛋白铁增加量和肝脏铁储存量，评估补充剂在两个测试因素（即给药途径和给药频率）上治疗缺铁的有效性。口服补充剂在改善贫血动物铁状态方面与腹腔内补充剂同样有效。然而，尽管体内铁储存量相等，但腹腔内补充剂组中从结扎肠袢吸收放射性铁测试剂量15分钟的吸收率（分别为11.68（标准差1.70）%、17.49（标准差4.59）%、16.71（标准差3.39）%）显著高于口服补充剂组（分别为3.24（标准差1.35）%、2.45（标准差1.05）%、1.80（标准差0.35）%）。在口服组中未检测到肠道铁吸收效率的显著差异，但仅补充一次的组在改善铁状态方面比接受3天每日补充剂的组更有效或同样有效，这由血红蛋白再生效率表明。我们得出结论，口服铁补充剂的给药存在黏膜阻断作用，但在口服铁补充期间这种阻断作用的程度并不像目前在每日铁补充计划疗效不佳的背景下所认为的那样显著。
