Serum Vitamin E Level as a Biomarker in Non-Alcoholic Fatty Liver Disease

Abstract

Introduction: Vitamin E treatment has been shown to be superior to placebo in non-alcoholic steatohepatitis in adults without diabetes. In this study, we aim to investigate the usefulness of serum vitamin E level as a biomarker of non-alcoholic fatty liver disease (NAFLD) severity using nationally representative data. Methods: Data was obtained from the Third National Health and Nutrition Examination Survey conducted from 1988-1994. NAFLD was defined by ultrasound detection of hepatic steatosis without other known liver diseases and categorized as normal, mild, moderate, or severe. The severity of hepatic fibrosis was determined by NAFLD fibrosis score (NFS). We used multivariate survey-weighted generalized logistic regression to evaluate the association between serum vitamin E level and the degree of NAFLD. We also performed subgroup analyses by BMI [lean (BMI < 25) vs classic (BMI≥25)] and diabetes status. Analyses were performed in R software version 3.2.2.Table: Table. Vitamin E level by NAFLD status on liver ultrasound findingsTable: Table. Vitamin E level by degree of NAFLD fibrosis score categoryResults: Among 10,921 people, 4,007 (34.4%) had NAFLD. By ultrasound findings, there were 1,488 people with mild, 1,703 people with moderate and 816 people with severe steatosis. There were 2,303 people with low NFS (< -1.455, no significant fibrosis), 1,342 people with intermediate NFS, and 277 people with high NFS (>0.676, advanced fibrosis). To better reflect vitamin E status, serum vitamin E levels were adjusted by cholesterol. Serum vitamin E level was associated with increased age (age 20-39: 5.24 ± 0.04ng/ml, 40-59: 5.88 ± 0.09ng/ml, and ≥60: 6.39 ± 0.09ng/ml, trend p-value < 0.01) and was lower in non-Hispanic blacks (4.95 ± 0.04ng/ml) and Hispanics (5.46 ± 0.03ng/ml) compared to non-Hispanic whites (5.81 ± 0.06ng/ml, p-value < 0.05). Vitamin E levels for normal, mild, moderate and severe steatosis were 5.60 ±0.05ng/ml, 5.71±0.09ng/ml, 5.93±0.11ng/ml, 5.90±0.10ng/ml, respectively (trend p-value= 0.294; table1). Vitamin E levels for low, intermediate and high NFS category were 5.63.7±0.06ng/ml, 6.00±0.13ng/ml, and 6.50±0.27ng/ml, respectively (trend p-value 0.794; table 2). Subgroup analyses by BMI and diabetes did not reveal an association of vitamin E with NAFLD severity. Conclusion: Despite therapeutic evidence of vitamin E, serum vitamin E levels varied significantly by age and race and was not associated with NAFLD severity.