January 2014 – Polyphenols in Human Health and Disease
The negative impact on iron bioavailability from plant-based foods has largely been demonstrated in humans by iron isotope absorption studies, although their impact on the human iron status is still unclear.High concentrations of polyphenols can be found in numerous vegetables, legumes, fruits and beverages. It is commonly assumed that, depending on their structure, polyphenols form insoluble complexes with iron in the gut and thereby inhibit its absorption. However, the complex formation of polyphenols and iron depends not only on polyphenol structure, but also on pH and the concentration of polyphenols and iron in the solution. Both vitamin C and EDTA (although the latter to a lesser extent) have been shown to protect iron against complex formation with polyphenols and increase its absorption. This chapter studies the negative and positive health aspects of polyphenols on iron absorption and their consequences, by discussing the results of both single and multiple meal studies in an effort to measure the impact of polyphenols on iron absorption.