Vegetable protein intake is associated with lower gallbladder disease risk: Findings from the Women's Health Initiative prospective cohort

Objective: This study aimed to measure associations between gallbladder disease and protein intake patterns, separated by quantity and type (vegetable vs. animal), among postmenopausal women. Methods: Analyses were based on 130,859 postmenopausal women enrolled from 1993 to 1998 at 40 U.S. clinical centers in the Women's Health Initiative clinical trials and observational study. Women were excluded if they reported a history of gallbladder disease prior to baseline. Cox proportional hazards regression models, adjusted for gallbladder disease risk factors, were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between energy-adjusted protein intake and gallbladder disease. Results: In this study sample, 8.1% of postmenopausal women self-reported incident gallbladder disease. In multivariate analysis, women in the highest quintile of energy-adjusted vegetable protein intake (>24.0 g/d) had a lower risk of gallbladder disease (HR, 0.87; 95% CI, 0.81-0.93) as compared to women in the lowest quintile (<16.3 g/d) (P_trend < 0.001). Total protein intake was modestly protective against gallbladder disease (P_trend < 0.021). Animal protein intake was not associated with gallbladder disease risk. The protective effect of vegetable protein held stable only for women without history of diabetes (HR, 0.86; 95% CI, 0.80-0.92) and without recent weight loss (HR, 0.88; 95% CI, 0.80-0.97). Conclusions: Vegetable protein intake is inversely associated with gallbladder disease risk in our sample of postmenopausal women. In addition to weight management, healthcare providers could emphasize vegetable protein as an additional dietary modality to promote lower risk for gallbladder disease.