Heme boosts non‐heme iron absorption in human intestinal Caco‐2 cells

There are two types of dietary iron, heme iron, derived from animal products, and non‐heme iron, derived from plant products. It has long been demonstrated that animal products such as meat, poultry and fish enhance non‐heme iron absorption in humans but the mechanism has never been adequately explained. While it was suggested that the presence of some proteins in animal products led to the increased non‐heme iron absorption, previous studies indicated that certain non‐protein enhancers in animal products could be responsible for the enhanced non‐heme iron absorption. In current study, we proposed that heme is a component of meat that actually boosts intestinal non‐heme absorption, which in turn increases dietary non‐heme iron absorption into circulation. To determine whether heme alone enhances intestinal non‐heme iron absorption, and to explore possible mechanisms, we initially studied the direct effect of heme on non‐heme iron absorption by adding heme during non‐iron absorption study using intestinal Caco‐2 cells. Our results suggest that heme alone induces non‐heme iron absorption. We also investigated whether heme treatments can alter the expression of iron transporting proteins. Our western blot data showed that heme treatments increase the expression of ferroportin‐1, possibly by modulating the transcription of ferroportin‐1 gene in Caco‐2 cells. The results suggest that that non‐heme iron absorption can be enhanced by heme.