title: Oxalate content of different drinkable dilutions of tea infusions after different brewing times.
abstract: BACKGROUND
  The aims of this study were to determine the effect of different brewing times and diluting on oxalate content of loose-packed black teas consumed in Tabriz, Iran.
  
  
  METHODS
  The oxalate content of black teas after brewing for 5, 10, 15, 30, 60 minutes was measured in triplicate by enzymatic assay. In order to attain the most acceptable dilution of tea infusions, tea samples which were brewed for 15, 30 and 60 minutes were diluted two (120 ml), three (80 ml) and four (60 ml) times respectively.
  
  
  RESULTS
  There was a stepwise increase in oxalate concentrations associated with increased brewing times (P< 0.001) with oxalate contents ranging from 4.4 mg/240 ml for the 5 min to 6.3 mg/240 ml for 60 min brewing times, respectively. There were significant differences between the mean oxalate content of different dilutions after brewing for 15, 30 and 60 minutes (P< 0.001).
  
  
  CONCLUSIONS
  The oxalate content of Iranian consumed black tea after different brewing times and different dilution was below the recommended levels. Therefore, it seems that consumption of black tea several times per day would not pose significant health risk in kidney stone patients and susceptible individuals.
authors.affiliation: Student Research Committee, Faculty of Health and Nutrition, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Neda
authors.initials: N
authors.lastname: Lotfi Yagin
authors.affiliation: Nutrition Research Centre, Faculty of Health and Nutrition, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Mahdavi
authors.affiliation: Student Research Committee, Faculty of Health and Nutrition, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Nikniaz
keywords: Black tea; Brewing times; Different dilutions; Kidney stones; Oxalate