The entry of most xeno/endobiotics into the organism is limited by their intestinal absorption. The interference of certain foods with the therapeutic efficacy of drugs or with chemical toxicity is becoming evident and growing attention is being given to these subjects. The aim of this work was to study the effect of green tea (GT) and black tea (BT), as well as some of their components, on the transport of organic cation molecules. For this purpose, 3H-MPP+ (radiolabeled 1-methyl-4-phenylpyridinium) was used as a model organic cation and Caco-2 cells were used as an intestinal epithelial model. Our results showed that both GT and BT significantly increased 3H-MPP+ absorption in these cells. Additionally, we studied the effect of epigallocatechin-3-gallate (EGCG), myricetin, caffeine, and theophylline. Whereas EGCG (2 mM) increased, myricetin (50 microM) and caffeine (1 mM) decreased, and theophylline (1 mM) had no effect on the uptake of 3H-MPP+ into Caco-2 cells. When GT was supplemented with caffeine or theophylline, we observed a partial loss of its effect. When BT was supplemented with EGCG, its ability to increase 3H-MPP+ uptake was much more pronounced than that observed with BT alone. In conclusion, this study showed that GT and BT might interfere with the absorption of the model organic cation MPP+ by the intestinal epithelium. Since important compounds are organic cations, the consequences of this interference may have an impact on human health. Although this constitutes only preliminary work and further studies are needed, tea should be included in the growing list of foodstuffs that have the potential to be involved in food-drug interactions.