Low vitamin D level was associated with metabolic syndrome and high leptin level in subjects with nonalcoholic fatty liver disease: A community-based study

Background: This study aimed to evaluate the association between serum vitamin D levels and nonalcoholic fatty liver disease (NAFLD) parameters, such as metabolic syndrome (MS), inflammatory cytokines (tumor necrosis factor, high sensitive C-reactive protein) and adipokines (adiponectin, leptin). Methods: From August 2013 to August 2016, a community-based study was performed in the north-eastern region of Taiwan. All subjects received a demographic survey, blood testing and abdominal ultrasonography (US). The vitamin D level was evaluated by quartile divide or used the classification of deficiency (< 20 ng/ml), insufficiency (20-30 ng/ml) and sufficiency (> 30 ng/ml). Results: Subjects were divided into NAFLD group and normal control (subjects number = 564 in each group) following abdominal US study and matching age and gender. The mean age was 57.1 years in NAFLD group and 57.5 in control group. Subjects in NAFLD group had a lower mean vitamin D than those in the control group (28.5 ± 9.5 ng/ml vs. 29.9 ± 10.2 ng/ml, P = 0.018). Subjects with serum vitamin D deficiency or insufficiency had higher odds for MS than those with sufficient vitamin D levels [deficiency vs. sufficiency, adjusted odds ratio (aOR) =1.860 (95% CI = 1.234-2.804), P = 0.003; insufficiency vs. sufficiency, aOR = 1.669 (95% CI = 1.237-2.251), P = 0.001]. Similarly, subjects in the lowest quartile of vitamin D had higher odds for MS than those in the highest quartile of vitamin D (aOR = 2.792, 95% CI = 1.719-4.538, P < 0.001). Vitamin D level was positively correlated with age and male, but negatively correlated with serum leptin level. Conclusion: Subjects with low vitamin D level had higher odds for MS, but higher levels of leptin, compared to those with high vitamin D levels.