Association of vitamin D supplementation with serum leptin and metabolic parameters in Egyptian patients with non-alcoholic steatohepatitis: a prospective study

Background Nonalcoholic steatohepatitis (NASH) is the progressive form of NAFLD, a common cause of liver disease, with increased chance of progression to liver fibrosis, cirrhosis, and hepatocellular carcinoma. Circulating leptin is increased in patients with NASH. It is an independent positive predictor of the severity of hepatic steatosis. Vitamin D is a lipophilic molecule essential to maintain calcium and phosphate balance. Moreover, it has antifibrotic, antiproliferative, and anti-inflammatory effects on the liver. Vitamin D deficiency is a worldwide condition and very common in patients with NASH. Low serum vitamin D has been shown to predispose to intrahepatic lipid accumulation leading to NAFLD. The aim of this study was to investigate the association of vitamin D supplementation with serum leptin and metabolic parameters in Egyptian patients with non-alcoholic steatohepatitis Results Patients with NASH group had statistically significant higher values of diastolic blood pressure (94.3 +/- 11.9 mmHg, p < 0.0001), glycated hemoglobin (8.0 +/- 2.4%, p < 0.0001), fasting blood sugar (165.6 +/- 62.0 mg/dL, p < 0.0001), fasting insulin level (24.2 +/- 3.0 mu U/ml, p < 0.0001), homeostatic model assessment of insulin resistance (HOMA-IR) (1.8 +/- 0.7, p < 0.0001), alanine transferase (ALT) (78.2 +/- 36.7 U/L, p < 0.0001), aspartate transferase (AST) (108.6 +/- 85.6 U/L, p < 0.0001), NAFLD fibrosis score (- 0.78 +/- 0.9, p < 0.0001), total cholesterol (233.0 +/- 40.9 mg/dL, p = 0.0011), low-density lipoprotein (117.5 +/- 41.6 mg/dL, p = 0.0084), and triglycerides (229.7 +/- 62.1 mg/dL, p < 0.0001) than the control group. Moreover, they had lower serum vitamin D level (15.6 +/- 6.6 ng/ml, p = 0.0004) and higher serum leptin level (35.9 +/- 28.4 ng/ml, p < 0.0001) than the control group. Following vitamin D supplementation, there was a statistically significant reduction in HbA1c (6.8 +/- 1.3%, p = 0.0055), fasting blood sugar (136.1 +/- 32.7 mg/dL, p = 0.0094), fasting insulin level (22.9 +/- 1.8 mu U/ml, p = 0.0236), HOMA-IR (1.4 +/- 0.4, p = 0.0026), ALT (55.3 +/- 21.3 U/L, p = 0.0010), AST (73.1 +/- 54.2 U/L, p = 0.0297), and triglycerides (203.6 +/- 49.8 mg/dL, p = 0.0415) in patients with NASH. There was a statistically significant increase in serum vitamin D level (33.0 +/- 7.6 ng/ml, p < 0.0001) and decrease in serum leptin level (23.5 +/- 12.9 ng/ml, p = 0.0140) after treatment. Conclusions Vitamin D supplementation in patients with NASH in a dose of 4000 IU/day for 12 weeks improves severity of hepatic inflammation, decreases insulin resistance, improves glycemic control, corrects dyslipidemia, and protects against lipotoxicity by inhibition of serum leptin.