The first aim of this study is to assess oxidative stress and nutritional status in patients with elevated liver enzymes who were found to have either simple steatosis (SS) or nonalcoholic steatohepatitis (NASH) or normal histological findings on liver biopsy by measuring liver lipid peroxides and tumor necrosis factor (TNF)-α, liver pathology and immunohistochemistry, liver function tests, liver and red blood cell membrane fatty composition, insulin resistance (IR) parameters, plasma lipid peroxides, plasma antioxidant vitamins and antioxidant power, lipid profile, subject demographics, medical history and medication use. The second aim is to detect differences in hepatic gene expression (messenger RNA, mRNA) and epigenetic regulation (micro RNA, miRNA) between patients with SS or NASH and healthy controls, in addition to determine in patients with non-alcoholic fatty liver disease (NAFLD = SS+NASH combined) whether there is an association between hepatic n-3 PUFA content and gene expression. The third aim is to determine the intestinal microbiome (microbial composition and metagenome) in patients with SS or NASH and healthy controls.