Dietary bioactive polyphenols inhibit heme iron absorption in human intestinal Caco‐2 cells

Abstract

Heme iron is an important source of dietary iron in humans. It is known that heme iron and non‐heme iron are absorbed differently. Recently, bioactive dietary polyphenols are receiving increasing interest due to their reported health benefits for a variety of disorders. Dietary polyphenolic compounds have a wide range of effects in vivo and vitro, including chelation of metals such as iron. We previously reported that bioactive polyphenols impair the utilization of dietary non‐heme iron in human intestinal cells. In the current study, we examined the influence of the dietary polyphenols, (‐) ‐epigallocatechin‐3‐gallate (EGCG) and grape seed extract (GSE) on heme‐55Fe absorption in Caco‐2 intestinal cells. The rate of heme iron absorption was linear (R> 0.99) during 7 hour incubation time. Both EGCG and GSE decreased the rate of heme iron absorption by > 85%. The addition of EGCG and GSE also significantly (P < 0.001) decreased heme iron transport across the basolateral membrane of enterocyte. However, apical heme iron uptake was significantly (P < 0.001) increased by addition of EGCG. Despite the increased cellular levels of 55Fe the transfer of 55Fe across the basolateral membrane of the enterocyte was extremely low in the presence of EGCG. Our data show that bioactive polyphenols also inhibit heme iron absorption by reducing basolateral iron exit rather than by decreasing apical heme iron uptake in intestinal cells. (Supported by the College of Human and Health Development at the PSU and USDA: 2005‐35200‐16543.)