Effect of Brewing Time on the Level of Fluoride Released from Black and Green Tea

Tea is a hyperaccumulator of fluoride and chronic fluoride intake is associated with multiple negative health outcomes. In this study, six brands of commercially available black and green tea were selected and the fluoride level in tea infusions tested using an ion-selective electrode method.

In this experimental study, the fluoride contents were determined using  ion-selective electrode (Mettler Toledo, USA) in four types of black tea and two types of green tea at different brewing time (3,5,15,30,60 and 120 min). The amount of tea fluoride at any time was investigated by repeated measure ANOVA and two-way ANOVA.

Repeated measure ANOVA analysis showed that fluoride release for green and black tea increased as increased brewing time (p<0.05). Based on the two-way ANOVA and Bonferroni test results, the mean of fluoride concentrations was high in B black tea in all brewing time. E green tea, D black tea, F green tea, A and C black tea released less fluoride respectively p≤0.05.

The results of this study showed that the fluoride content of black and green tea in different companies was different. In regard to the impact of the cultivation site and the plant characteristics which the tea is made, companies should include enough information about their product to inform consumers. The amount of fluoride in the all examined tea increases after 3 and 120 min of brewing.