Background and aim
Nonalcoholic fatty liver disease (NAFLD) and vitamin D deficiency are associated with insulin resistance, type 2 diabetes, and dyslipidemia. Many studies have examined the association between vitamin D and NAFLD, but the results have been contradictory. Our aim was to investigate the association of serum vitamin D assessed by 25-hydroxyvitamin D [25 (OH) vitamin D] with NAFLD and to analyze the role of insulin resistance and dyslipidemia.
Patients and methods
A total of 60 patients with NAFLD, chosen from the gastroenterology outpatient clinic of Internal Medicine, Kasr Al-Ainy Hospital, Cairo University, were included in the study. They were classified into three groups (group 1: 20 diabetic patients; group 2: 20 dyslipidemic patients; and group 3: 20 nondiabetic nondyslipidemic patients). In addition, 20 healthy control individuals were also included. For all participants, clinical and biochemical data were obtained, liver ultrasonography for the diagnosis of fatty liver disease was performed, and serum 25 (OH) vitamin D was measured.
Results
Our data showed that NAFLD patients had lower levels of 25 (OH) vitamin D (15.7 ± 10 nmol/l) compared with controls (43.4 ± 14 nmol/l), with a statistically significant difference between the two groups. There was a statistically significant inverse correlation between 25 (OH) vitamin D and low-density lipoprotein and triglyceride among the studied groups, whereas no significant correlation was detected with other variables. The receiver operating characteristic curve showed that 25 (OH) vitamin D was better positive than negative in discriminating between NAFLD patients and controls at a cutoff of 18. The sensitivity was 99% and specificity was 77%, with an excellent area under the curve of 0.94.
Conclusion
Low 25 (OH) vitamin D levels were associated with the presence of NAFLD independently of age, sex, type 2 diabetes mellitus, and insulin resistance.