Fluoride Concentrations in Regular and Decaffeinated Teas

Objectives: Leaves of the tea plant, Camellia sinensis, accumulate fluoride to very high concentrations ([F]). Recent research indicates that excessive, chronic consumption of tea is a risk factor for skeletal fluorosis. A previous study found that the fluoride concentrations in brewed decaffeinated tea (DCT) brands were significantly higher than in regular tea (RT). The present study was done to provide more information on this subject.  Methods: Seven pairs of DCT and RT, each pair with the same flavor and manufacturer, were brewed with deionized water according to the manufacturer’s directions and analyzed with the ion-specific electrode using two different preparatory methods: the ‘direct’ method (addition of TISAB) and the HMDS-facilitated diffusion method. The results were analyzed for significant differences using ANOVA.  Results: The [F] in brewed DCT brands were not consistently higher than in the RT brands. The results using the HMDS-diffusion method indicated that DCT [F] were lower than RT [F] in three of the seven pairs (4.88/5.98, 3.40/4.86, 2.93/3.95 mg/L), virtually the same in two pairs (3.92/4.18, 3.90/4.02), and higher in two pairs (3.24/1.16, 7.05/2.50). Overall, the difference between the DCT and RT [F] was not statistically significant (p>0.50). The results using HMDS diffusion, however, were higher than those using the direct method (p<0.025).  Conclusions: Decaffeinated and regular teas produced by the same manufacturers have different F concentrations in the brewed tea. Unlike an earlier study that reported DCT had higher [F] than RT, however, we found the relationship to be unpredictable. There are at least two possible explanations: (1) The use of different methods of decaffeination by different manufacturers; (2) Decaffeinated and regular teas distributed with the same brand name were grown in different regions of the same country or in different countries.