Daily Green Tea Infusions in Hypercalciuric Renal Stone Patients: No Evidence for Increased Stone Risk Factors or Oxalate-Dependent Stones

Abstract

Green tea is widely used as a ‘’healthy’’ beverage due to its high level of antioxidant polyphenol compounds. However tea is also known to contain significant amount of oxalate. The objective was to determine, in a cross-sectional observational study among a population of 273 hypercalciuric stone-formers referred to our center for metabolic evaluation, whether daily green tea drinkers (n = 41) experienced increased stone risk factors (especially for oxalate) compared to non-drinkers. Stone risk factors and stone composition were analyzed according to green tea status and sex. In 24-h urine collection, the comparison between green tea drinkers and non-drinkers showed no difference for stone risk factors such as urine oxalate, calcium, urate, citrate, and pH. In females, the prevalence of calcium oxalate dihydrate (COD) and calcium phosphate stones, assessed by infrared analysis (IRS) was similar between green tea drinkers and non-drinkers, whereas prevalence of calcium oxalate monohydrate (COM) stones was strikingly decreased in green tea drinkers (0% vs. 42%, p = 0.04), with data in accordance with a decreased oxalate supersaturation index. In males, stone composition and supersaturation indexes were similar between the two groups. Our data show no evidence for increased stone risk factors or oxalate-dependent stones in daily green tea drinkers.

Tea in Health and Disease

“…Rode et al, determined, in a cross-sectional observational study among a population of 273 hypercalciuric stone-formers, whether daily green tea drinkers experienced increased stone risk factors (especially for oxalate) compared to non-drinkers, and found no evidence for increased stone risk factors or oxalate-dependent stones in daily green tea drinkers [14].…”

Preprotection of Tea Polysaccharides with Different Molecular Weights Can Reduce the Adhesion between Renal Epithelial Cells and Nano-Calcium Oxalate Crystals

“…The molecular weight of TPSs affected their protective effect on HK-2 cells. The cell membrane cannot be crossed when the molecular weights of the TPSs were large (e.g., 10.88 kDa of TPS0) [25,26]. However, the hydrogen chain was weak, and the active helical structure was not formed because of the short sugar chain [27,28] when the molecular weight of TPSs was small (such as 2.31 kDa of TPS3), thereby leading to a decrease in the protective effect.…”

“…The main component of kidney stones is calcium oxalate (CaOx) [7]. The antistone effect of tea has become the focus of researchers [8][9][10][11]. Alhaji herbal tea prevents the formation of CaOx kidney stones at high concentrations of calcium and oxalate ions [8].…”

“…Blumea balsamifera (sambong) tea can form small stones that can be easily eliminated through urination because of the decrease in surface free energy and increase in nucleation rate [9]. Rode et al [10] showed that the prevalence of CaOx monohydrate (COM) stones immensely decreases among green tea drinkers in a population of 273 hypercalciuric stone formers. Chen et al [11] evaluated 13842 subjects with kidney stones through ultrasound and observed that the amounts of daily tea consumption are 119:2 ± 306:8 and 131:7 ± 347:3 mL in groups with and without renal stone disease, respectively.…”

Physicochemistry in medicine: some selected examples

“…Our data show no evidence for increased stone risk factors or oxalate-dependent stones in daily green tea drinkers. 104 Fourier transform infrared spectroscopy FT-IR spectroscopy has been proved to be a powerful characterisation tool for investigations on inorganic as well as organic chemical compounds in both qualitative and quantitative modes. 46,47 This technique is nondestructive and label-free.…”