ARS | Publication request: Effects of Tea Phenolics on Iron Uptake from Different Fortificants by Caco-2 cells

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 2009
Publication Date: August 1, 2009
Citation: Laparra, J., Glahn, R.P., Miller, D.D. 2009. Effects of Tea Phenolics on Iron Uptake from Different Fortificants by Caco-2 cells. Food Chemistry. 115(3):974-981.

Interpretive Summary: Our lab has developed a model for studying mineral absorption from different foods and food combinations. Food samples undergo a simulated digestion and are placed over Caco-2 cells, which act as a mimic of the intestinal lining. An increase in cell ferritin (an iron storage protein) formation was used as a measure of iron uptake. Previous studies have shown that some food or drink components can impair iron absorption. A very commonly consumed beverage ,tea, has been related to decreased iron absorption due to its polyphenol content. This study is to assess what group of phenols from green and black tea may be involved in, and the way they presumably inhibit iron absorption to Caco-2 cells. Results indicate the need to evaluate real foods, which affect Fe uptake in a different way than pure polyphenols do. A special consideration on the fortificant used is needed. The lowest inhibitory effect on Fe uptake was noted from ferrous forms of iron used as fortificants.

Technical Abstract: The in vitro effects of tea phenolics on Fe uptake from different fortificants (FeSO4, FeCl3, FeEDTA) by Caco-2 cells were compared. Cell cultures were exposed to catechin, tannic acid, green or black tea solutions added within Fe-containing solution, or used to pre-treat cell cultures before Fe-exposure. Cell ferritin formation was used as a measure of Fe uptake. Reverse phase chromatography was used to identify specific phenolics in tea solutions, and the Fe-binding catechol and galloyl groups were determined spectrophotometrically. The results showed a positive effect of catechin on Fe uptake only from dissociable Fe sources, and a marked inhibitory effect of tannic acid regardless the Fe source. Tea phenolics exhibit a similar inhibitory pattern on Fe uptake from FeCl3 and FeEDTA solutions; however, the Fe uptake from FeSO4 solutions was significantly less affected. These data improve the understanding of interactions by which tea phenolics affect Fe uptake at intestinal level.