Chromium in tea leaves

Tea is a foodstuff that can accumulate mineral and trace elements. 50 different kinds of tea that had been imported from various tea producing countries were analysed. The average value of all these varieties was 0.796 ppm chromium. Black tea yielded an average of 0.716 ppm and green tea an average of 0.906 ppm. Altogether 8 kinds of tea had a chromium content above 1 ppm. After preparing the tea samples (2 g tea boiled with 100 mi water for 5 resp. 15 minutes) the extraction rate was determined. With this procedure 18.6 to 30.0 % of the total chromium were solubilised except Assam BOP CTC tea. The Assam BOP CTC tea showed a special value of total chromium (4.450 ppm) and an outstanding value for the extraction rate (40.9 %). An explanation is that only this kind of tea was processed with the CTC (crushing tearing curling) technique. The boiling of tea for 5 resp. 15 minutes did not have a great effect on the extraction rate. These values correspond to the ones found in literature. Since 1996 the WHO recommends a minimum mean intake of 33 mu g chromium per day as a normative requirement. In relation to this recommendation tea can cover about 5 % of the chromium supply.