Background: This study determined the fluoride content of green tea from various parts of Asia, where green tea originates.
Methods: We brewed 2.5 g each of 4 types of green tea (from China, South Korea, Japan and Sri Lanka) using deionized water heated to boiling. Water was cooled to 71°C, then tea was steeped for 2 minutes. This process was repeated 20 times, thus providing 20 samples for each tea type. In addition, 20 control samples of deionized water were brewed to the same specifications. Samples were analyzed using a fluoride probe, and statistical power was calculated.
Results: The tea samples from different countries varied in the amount of fluoride they contained. The Chinese sample contained the most fluoride, while the Japanese sample contained the least. Means and interquartile ranges of fluoride concentration were calculated for each sample: Sri Lanka 3.58 ppm (0.1425), Chinese 6.83 ppm (0.140), South Korean 5.36 ppm (0.0975), Japanese 1.88 ppm (0.1375) and control 0.33 ppm (0.0078).
Conclusion: The origin of tea and environmental factors, such as pollution, groundwater, air and the soil in which it was grown appear to directly affect the amount of fluoride that accumulates in the plants. Considering the fluoride content revealed by this study, green tea consumption habits should be taken into account when prescribing adjunct fluoride therapy as part of a preventative program for patient care.