Regulatory mechanisms of intestinal iron absorption: Iron-deficient mucosal cells respond immediately to dietary iron concentration

Abstract

Iron is a nutrient and its deficiency is the most frequent nutritional disorder worldwide, occurring in 4 to 5 billion people corresponding to about 70-80% of the world's population as estimated by the World Health Organization. However, an excess of iron increases oxidative stress and increases the risk of death and cancer; thus blood transfusion and supplementation should be used with caution. As there is no mechanism for deliberate iron excretion, the regulation of iron absorption in the small intestine is required to maintain total body iron balance and prevent excessive or deficient iron levels. Proteins involved in intestinal iron absorption were first identified in 1997. Molecular mechanisms of iron transport from the lumen of the small intestine to the portal blood through epithelial cells have been elucidated. In addition to long responses to iron deficiency in vivo, a short response exists for iron concentrations in the small intestine. This review describes regulatory mechanisms at the forefront of iron absorption, focusing on short acting mucosal block.

Oral iron supplementation and anaemia in children according to schedule, duration, dose and cosupplementation: a systematic review and meta-analysis of 129 randomised trials

“… 26 27 Some evidence points to changes in gastrointestinal epithelial cells following a large bolus of iron that results in reduced transport of iron into portal blood. 28 A prior meta-analysis of 21 trials concluded that, compared with daily iron supplements, intermittent supplementation had similar effects on haemoglobin levels but was less effective in reducing anaemia. 29 Our findings, based on a much larger number of trials, suggest that frequent and intermittent supplementation are similarly effective in reducing anaemia.…”

“…Furthermore, since mammalian gastrointestinal epithelial cells turn over every 2–6 days, weekly supplementation may not be at a great disadvantage relative to daily supplementation with respect to the total amount of absorbed iron 26 27. Some evidence points to changes in gastrointestinal epithelial cells following a large bolus of iron that results in reduced transport of iron into portal blood 28. A prior meta-analysis of 21 trials concluded that, compared with daily iron supplements, intermittent supplementation had similar effects on haemoglobin levels but was less effective in reducing anaemia 29.…”