Association Between Vitamin D Levels and Nonalcoholic Fatty Liver Disease in Bariatric Surgery Candidates

Introduction: Vitamin D acts on a series of regulatory and signaling processes in the liver parenchyma, which are closely related to energy metabolism and inflammatory responses. This immune-inflammatory role is particularly interesting for understanding the correlation between serum vitamin D levels, obesity, and nonalcoholic fatty liver disease (NAFLD). Methods: This retrospective observational study collected secondary data from medical records of patients who underwent bariatric surgery with vertical gastrectomy from 2014 to 2018. After applying the inclusion and exclusion criteria, 164 patients were selected, with preoperative analysis of anthropometric, clinical, biochemical, and imaging parameters. Results: The group without steatosis showed higher serum vitamin D levels (in median) when compared to the groups with mild and moderate/severe steatosis, respectively. When vitamin D status and variables related to social drinking, body mass index degree, and lipid profile were evaluated, only alcohol consumption was associated with vitamin D insufficiency (p = 0.042). Conclusions: There is a high prevalence of vitamin D insufficiency/deficiency in the bariatric surgery preoperative period. Furthermore, it was not possible to establish a causal relationship between vitamin D deficiency and NAFLD, notwithstanding the verification of higher serum vitamin D levels in individuals who did not have liver lesions on ultrasonography.