A comparison of aluminum levels in tea products from Hong Kong markets and in varieties of tea plants from Hong Kong and India.

This study project aimed to investigate the concentrations of aluminum (Al) in tea products available in Hong Kong markets. Tea samples consisting of 47 different tea bags and 28 samples of tea leaves were analysed for concentrations of Al. All tea samples released Al (0.70-5.93 mg L(-1)) during a standard infusion period. In comparison to the Joint FAO/WHO Provisional Tolerable Weekly Intake guideline of 7 mg Al kg(-1) body weight, it was concluded that tea made with these tea leaves will not impose adverse human health impacts. The relative effects of age, soil available Al, and genetic differences on the levels of Al accumulated by tea bushes were investigated. It was found that there was no definite trend between the amount of Al accumulated and the age of tea bushes. The soil available Al influenced the levels of Al in Camellia sinensis to a certain extent, but it was evident that the ability of different varieties of C. sinensis to accumulate Al was variable. C. sinensis accumulated Al in all stages of growth. Young seedlings had lower contents of Al while the mobility of Al within the tea bushes was high. In a manner typical of hyperaccumulators, Al was not retained in the roots, but was consistently transported to the shoots. Aluminum in the tea bush was distributed between the different parts in the following order: mature leaves>roots>branches>young leaves.

Aluminium and fluoride contents of tea, with emphasis on brick tea and their health implications.

Tea plant takes up a large quantity of aluminium (Al) and fluoride (F) from acidic soils. It has been known that fluorosis can be developed for people who consume a large quantity of tea made from brick tea, a low quality tea consisting mainly of old tea leaves in China. In addition, it has been claimed that Alzheimer's disease (AD) is linked with the Al content in the human brain. Therefore, the high Al content in tea, especially brick tea is also a concern. This article reviews the basis background on tea including classification, growth conditions, types of tea leaves and their production, and processing of tea. Special emphasis is made on the transfer of Al and F from soil to tea plant and then to tea liquor. Health implications of drinking a large quantity of tea liquor especially those made from brick tea are discussed. Recommendations are suggested to reduce the uptake of these two elements by tea plant, and lower their contents in tea products.