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Green tea intake and risk of incident kidney stones: Prospective cohort studies in middle‐aged and elderly Chinese individuals
Author(s) -
Shu Xiang,
Cai Hui,
Xiang YongBing,
Li Honglan,
Lipworth Loren,
Miller Nicole L,
Zheng Wei,
Shu XiaoOu,
Hsi Ryan S
Publication year - 2019
Publication title -
international journal of urology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 67
eISSN - 1442-2042
pISSN - 0919-8172
DOI - 10.1111/iju.13849
Subject(s) - medicine , hazard ratio , confidence interval , prospective cohort study , proportional hazards model , cohort study , demography , traditional medicine , sociology
Objectives To investigate the association between green tea intake and incident stones in two large prospective cohorts. Methods We examined self‐reported incident kidney stone risk in the Shanghai Men's Health Study ( n = 58 054; baseline age 40–74 years) and the Shanghai Women's Health Study ( n = 69 166; baseline age 40–70 years). Information on the stone history and tea intake was collected by in‐person surveys. Multivariable Cox proportional hazards models were adjusted for baseline demographic variables, medical history and dietary intakes including non‐tea oxalate from a validated food frequency questionnaire. Results During 319 211 and 696 950 person‐years of follow up, respectively, 1202 men and 1451 women reported incident stones. Approximately two‐thirds of men and one‐quarter of women were tea drinkers at baseline, of whom green tea was the primary type consumed (95% in men, 88% in women). Tea drinkers (men: hazard ratio 0.78, 95% confidence interval 0.69–0.88; women: hazard ratio 0.8, 95% confidence interval 0.77–0.98) and specifically green tea drinkers (men: hazard ratio 0.78, 95% confidence interval 0.69–0.88; women: hazard ratio 0.84, 95% confidence interval 0.74–0.95) had lower incident risk than never/former drinkers. Compared with never/former drinkers, a stronger dose–response trend was observed for the amount of dried tea leaf consumed/month by men (hazard ratio highest category 0.67, 95% confidence interval 0.56–0.80, P trend < 0.001) than by women (hazard ratio highest category 0.87, 95% confidence interval 0.70–1.08, P trend = 0.041). Conclusions Green tea intake is associated with a lower risk of incident kidney stones, and the benefit is observed more strongly among men.