Presentation Authors: Joshua Calvert*, Xiang Shu, Hui Cai, Nashville, TN, Yong-Bing Xiang, Honglan Li, Shanghai, China, People's Republic of, NIcole Miller, Wei Zheng, Xiao-Ou Shu, Ryan Hsi, Nashville, TN
Introduction: Animal protein intake is a risk factor for nephrolithiasis. Whether fruit and vegetable sources of protein associate with kidney stone risk is not well studied. We sought to better describe the association of animal and plant sources of protein with kidney stone risk.
Methods: We examined the association of intakes of animal (dairy + non-dairy) and plant protein (fruit + vegetable) and risk of incident, or first time kidney stones in the Shanghai Women's Health Study (SWHS, n=67,715, baseline age 40-70 years) and the Shanghai Men's Health Study (SMHS, n=56,852, baseline age 40-74 years). Dietary intakes were obtained from validated food frequency questionnaire at baseline and stone event histories were collected at both baseline and during the follow-ups. Cox regression models were used to evaluate the associations of protein intakes with stone risk with adjustment of demographics, medical history, and dietary intakes.
Results: During 319,211 and 696,950 person-years of follow-up, respectively, 1,451 men and 1,202 women reported incident stones. MeanÂ±SD animal and plant protein intakes were respectively 31.3Â±13.7 and 48.4Â±7.2 g/day/2000 Kcal for women and 30.8Â±13.3 and 51.3Â±7.6 g/day/2000 Kcal for men. On multivariable Cox regression analysis, women in the highest quintile of animal protein consumption, showed an increased risk of incident stone formation compared to the lowest quintile (HR=1.20, 95% CI 1.01- 1.44, Ptrend= 0.04). No association was seen among men. Greater animal to plant protein ratios and non-dairy animal to plant ratios of intake were each associated with increased risk among women (both Ptrend < 0.05), but not among men. Plant protein intake was not associated with risk for both groups.
Conclusions: Among this population of relatively low animal protein intake and high plant protein intake, greater animal protein intake is associated with stone risk among women. Lowering the proportion of animal protein relative to plant protein intake may be protective in women.