Xiang Shu1, Hui Cai1, Yong-Bing Xiang2, Honglan Li2, Loren Lipworth1,3, Nicole L Miller4, Wei Zheng1, Xiao-Ou Shu1, Ryan S Hsi4. 1. Division of Epidemiology, Department of Medicine, Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA. 2. State Key Laboratory of Oncogene and Related Genes, Department of Epidemiology, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. 3. Vanderbilt O'Brien Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, Tennessee,, USA. 4. Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
Abstract
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 ratiohighest category 0.67, 95% confidence interval 0.56-0.80, Ptrend < 0.001) than by women (hazard ratiohighest category 0.87, 95% confidence interval 0.70-1.08, Ptrend = 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.
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 ratiohighest category 0.67, 95% confidence interval 0.56-0.80, Ptrend < 0.001) than by women (hazard ratiohighest category 0.87, 95% confidence interval 0.70-1.08, Ptrend = 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.