Tea components influencing bioavailability of fluoride and potential transport mechanism in the Caco-2 cell line model

Previous work showed that the bioavailability of fluoride in dark tea was lower than NaF solution. However, limited information is available indicating the effects of tea components on the fluoride bioavailability. In this study, the effects of the components in tea on the bioavailability of fluoride were evaluated in the Caco-2 cell line model. Additionally, the mechanism of effect of aluminium on fluoride transport was investigated. The result showed that 10-100 mu m of epigallocatechin gallate (EGCG) could not influence fluoride transport. Al3+ significantly decreased fluoride transport in both apical-basolateral and basolateral-apical directions. Moreover, aluminium could form different forms of aluminium fluoride complexes, which were transported through Caco-2 cells by different pathways. F- transport was mainly dependent on the paracellular pathway and active transport involving Cl- channels. The paracellular pathway played a predominant role in transport of AlF3. The paracellular pathway and active transport both participated in AlF2+ transport.