Element composition of tea leaves and tea infusions and its impact on health

Tea infusion is the most frequently consumed beverage worldwide next to water, with about 20 billion cups consumed daily. In Taiwan, daily consumption averages 2.5 cups of tea infusion per person. Many studies have concluded that tea has numerous beneficial effects on health. However, some undesirable trace elements, such as arsenic, chromium, cadmium, lead, etc., are a concern. This study has three aims: (1) to measure the concentrations of arsenic and heavy metal elements, such as chromium, cadmium, and lead, as well as the essential trace elements contained in dried tea leaves of the common brands in Taiwan; (2) to determine the percentage released and concentration of each of these elements after infusion of these tea leaves with boiling water; (3) to assess the carcinogenic risk from daily tea consumption, to provide reference values for the general public. This study showed the total content of arsenic and heavy metals in green tea, oolong tea, and black tea produced in Taiwan was 0.11, 5.61, and 10.11 microg/g, respectively, indicating that the level of arsenic and heavy metal contamination of tea leaves was lower in Taiwan than other regions of the world. The hazard index (HI) of daily tea drinking of green tea, oolong tea, and black tea was low and within the bounds of safety (<1). Tea is an indispensable part of everyday life for many people in Taiwan, studies should continue to ensure that public health is maintained.