Daily Green Tea Infusions in Hypercalciuric Renal Stone Patients: No Evidence for Increased Stone Risk Factors or Oxalate-Dependent Stones
Sorbonne Université, Service d’Explorations Fonctionnelles Multidisciplinaires, AP-HP, Hôpital Tenon, 75020 Paris, France
Laboratoire de Chimie Physique, Université Paris-Sud, Bat 349, 91405 Orsay, France
Centre National de la Recherche Scientifique (CNRS), Département de Physique, 91405 Orsay, France
Sorbonne Université, GRC n°20, Groupe de Recherche Clinique sur la Lithiase Urinaire, Hôpital Tenon, F-75020 Paris, France
Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-S 1155 Paris, France
Service d’Urologie, Hôpital Henri Mondor, Assistance Publique-Hôpitaux de Paris, 94000 Créteil, France
Sorbonne Université, Service d’Urologie, AP HP, Hôpital Tenon, 75020 Paris, France
Author to whom correspondence should be addressed.
Nutrients 2019, 11(2), 256; https://doi.org/10.3390/nu11020256
Received: 11 December 2018 / Revised: 15 January 2019 / Accepted: 22 January 2019 / Published: 24 January 2019
(This article belongs to the Special Issue Tea in Health and Disease)
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.