Dietary Fat and Protein Intake Are Not Associated With Incident Biliary Sludge and Stones During Pregnancy

Background: Dietary composition can cause insulin resistance, elevated serum lipid levels, and obesity, all of which predispose to gallstone formation. The effects of dietary fat (including individual fatty acids) and protein on gallstone formation are controversial. The aim of this study was to examine the effects of dietary fat and protein intake on incident gallstone disease during pregnancy, a high-risk time for stone formation. Methods: We prospectively studied 3070 pregnant women who underwent serial gallbladder ultrasound examinations during pregnancy and at 4-6 weeks postpartum. All women had at least 2 study ultrasounds for comparison. A semi-quantitative food frequency questionnaire was completed by subjects in the early third trimester. Multivariate logistic regression was performed to assess the risk of incident gallbladder disease across quartiles of intake of total fat, individual fatty acids (polyunsaturated, monounsaturated, saturated, and total trans-fatty acids, as well as cholesterol), protein, and protein subtype (animal or vegetable based). Results: The cumulative incidence of new biliary sludge/stones or progression of baseline sludge to stones was 10.2% by 4-6 weeks postpartum. There was no association between total dietary fat (odds ratio [OR], 1.18; 95% confidence interval [CI], 0.64-2.18 comparing lowest and highest quartiles) or protein intake (OR, 0.83; 95% CI, 0.44-1.22 comparing lowest and highest quartiles) and incident gallbladder disease. There was also no association between individual fatty acids or protein subtype and gallbladder disease. Conclusions: Neither total nor subtype of dietary fat or protein was associated with incident biliary stone or sludge formation in this cohort of pregnant women.