Oxalate, magnesium and calcium content in selected kinds of tea: impact on human health

摘要

The aim of the study was to determine oxalate content in black, dark and green teas as well as to estimate the content ratio of Mg to Ca in tea infusions that is significant for patients with kidney stones. Atomic absorption spectrometry was used to determine Ca and Mg, while oxalate was analyzed by manganometric method. The highest levels of oxalate were found in black and dark tea (156 and 224 mg/200 mL, respectively) and the lowest in green tea (80 mg/200 mL). The greatest degree of leaching to tea infusions was determined for Mg in green (37 %) and black tea (34 %). The lowest percentage of leaching was estimated for Ca (7 %) in black tea. It was concluded that people with hyperoxaluria or a tendency to form kidney stones should consume tea, especially this of darker color, in moderate quantities.