For those who form calcium oxalate stones, which one is healthier?

Abstract

PurposeAlthough black tea is commonly consumed in Iran, within the last years the popularity of green tea, especially green tea bags, has dramatically increased due to all scientific papers reporting that green tea has benefit impacts on human health. Considering the postulated role of increased dietary oxalate intake on calcium oxalate stone formation, this paper aimed to study the oxalate content of most popular green and black tea bags consumed in Iran.Design/methodology/approachFive green tea samples and ten black tea samples were purchased from various markets in Tabriz, Iran. The oxalate content of each sample after infusion for five minutes was measured in triplicate using an enzymatic assay. Statistical analysis used: the ANOVA with Tukey's post‐hoc test, and also an independent t‐test were used for statistical analysis.FindingsThe oxalate concentration in different brands of green tea bags ranged from 0.73 to 1.75 and from 3.69 to 6.31 mg/240 ml for black tea bags. There were significant differences in oxalate content of different brands, both in green and black tea bags (P<0.001). The mean oxalate content of green and black tea samples also differed significantly from each other (P<0.001).Originality/valueFrom the oxalate point of view, consumption of green and black tea bags infusions several times per day may not pose significant health risks in kidney stone patients and susceptible individuals.