Non-alcoholic Fatty Liver Disease and Gallstones: A Systematic Review

Non-alcoholic fatty liver disease (NAFLD) is steatosis of the liver that resembles alcohol-induced liver injury but is a metabolic disorder. Most patients are obese with increased triglyceride levels due to increased intake of fatty food, which can cause excess fat to build up in the liver. At the same time, continuous ingestion of fatty foods can lead to gallstones (GS) due to the overproduction of cholesterol. NAFLD and GS have been seen to coincide, and there might be a relationship between them. This systematic review analyzes the incidence of NAFLD and GS to determine a bidirectional relationship. A comprehensive literature review was done using ProQuest, PubMed, and ScienceDirect, and included only experimental studies and meta-analyses. The search included the keywords 'gallstones and non-alcoholic fatty liver disease' and 'cholelithiasis and non-alcoholic fatty liver disease'. Our initial search included 10,665 articles and was narrowed down to 19 through extensive inclusion and exclusion criteria. There is a bidirectional relationship between the incidence of NAFLD and GS, where an increase in either can lead to an increase in the other. Both NAFLD and GS share similar risk factors leading to the development of each disease. On average, there's an increase in the prevalence of gallstones in NAFLD patients, and patients with GS were also more likely to have NAFLD. There was a prevalence of NAFLD in those with asymptomatic gallstones as well, indicating that the risk factors are crucial in the development of both. As a result, some research is determining whether an evaluation of the liver should be routine during cholecystectomy due to the increased risk of developing NAFLD.