Dietary Animal Protein vs. Plant Protein Sources in Relation to the Risk of Biliary Stone: A Case-Control Study

Background: Dietary intake is one of the modifiable risk factors for biliary stones. In recent studies, plant protein intake is associated with a lower risk of biliary stones in comparison to animal protein intake; however, the results are contradictory. The current study aims to compare the effect of animal protein and plant protein on the formation of biliary stone in one of the gastroenterology and liver disease centers in Iran. Methods: 110 participants who had a history of biliary stone and 230 controls who were normal in terms of biliary diseases and referred to the medical center from November 2017 to October 2018 enrolled in this study. Food frequency questionnaire (FFQ) was used for the nutritional assessment; moreover, demographic and anthropometric data, habitual history and comorbidities were collected. Statistical analysis was conducted by SPSS software. Results: Plant protein consumption was significantly lower (P=0.03) and animal protein intake was significantly higher (P=0.02) among men in case compared to controls. Furthermore, the relationship between biliary stone disease and animal protein intake was significant in crude model for men (OR: 1.03, 95% CI=1.01-1.05). In addition, the risk of biliary stone was significantly lower in patients with higher consumption of plant protein (for women: OR: 0.94, 95% CI=0.89-0.99, for both sexes: OR: 0.96, 95%CI=0.93-0.99). Conclusion: The present study suggested that consumption of animal protein sources increased the risk of biliary stone, and intake of plant protein sources decreased the risk of biliary stone.