Low 25 (OH) vitamin D levels are associated with increased prevalence of nonalcoholic fatty liver disease and significant liver fibrosis

Evidence on the role of 25-Hydroxyvitamin D (25(OH)D) in the occurrence and progression of nonalcoholic fatty liver disease (NAFLD) is conflicting and population-based data are scarce. Here, we assess the association between 25(OH)D levels, NAFLD and liver fibrosis in the general population.This is an analysis of data from the 2017-2018 cycle of the National Health and Nutrition Examination Survey. We included adult participants with available data on vibration-controlled transient elastography (VCTE) and without viral hepatitis and significant alcohol consumption. Steatosis and fibrosis were diagnosed by the median values of controlled attenuation parameter (CAP) and liver stiffness measurement (LSM), respectively. 25(OH)D was measured by high performance liquid chromatography-tandem mass spectrometry.A total of 3970 participants (1928 men and 2042 women) were included in the study. The prevalence of NAFLD (CAP ≥ 274 dB/m) and significant liver fibrosis (LSM ≥ 8 kPa) were 41.7% (95% CI 39.4-44.0) and 8.4% (95% CI 7.0-9.9), respectively, while 21.1% (95% CI 17.3-25.4) of participants had low 25(OH)D levels (<50 nmol/L). A multivariable logistic regression model adjusted for age, sex, race-ethnicity, body mass index, waist circumference, calendar period, diabetes, chronic kidney disease, and vitamin D supplementation showed that compared with participants with low 25(OH)D, those with optimal levels (≥75 nmol/L) had lower odds of both NAFLD (OR 0.73, 95% CI 0.55-0.98 p = 0.038) and significant liver fibrosis (OR 0.65, 95% CI 0.44-0.96, p = 0.033).An inverse relationship was found between 25(OH)D and NAFLD and fibrosis, suggesting a possible role of vitamin D in NAFLD occurrence and progression.