Prevalence of gallstones in the adult European population is ̴20 % (mostly cholesterol stones in the gallbladder). Obesity, metabolic syndrome, type 2 diabetes, female sex, pregnancy, multiparity and rapid weight loss (e.g. during very low calorie dieting and in the first year after bariatric surgery) are the most important risk factors. Nucleation of cholesterol crystals is the earliest obligatory step in cholesterol gallstone formation. Various conditions promote the crystallization process, such as bile concentration, biliary cholesterol supersaturation, excess hydrophobic bile salts and abundant pro-nucleating mucin.
