The purpose of this interventional study is to evaluate the efficacy and tolerability of docosahexaenoic acid (DHA) in children or adolescents with well-characterized and liver biopsy confirmed nonalcoholic fatty liver disease (NAFLD).

Sixty children or adolescents (4-16 years) with liver biopsy proven NAFLD will be enrolled. They will be randomized to treatment with DHA 250 mg/kg/d (n=20), DHA 500 mg/kg/d (n=20), or an identical placebo (n=20) given orally for a period of 24 months. All patients will be included in a lifestyle intervention program consisting of a diet tailored on the individual requirements and physical exercise.

Patients will undergo a medical evaluation every three months during the 24-month study period. Liver biopsy will be performed only at baseline and at the end of treatment. Anthropometric analysis, laboratory tests, including liver enzymes and lipids will be repeated at 3-month intervals during the 24-month study duration. Ultrasonography and Fibroscan of the liver will be repeated at the end of the study period.

Inclusion Criteria:

• persistently elevated serum aminotransferase levels
• diffusely echogenic liver on imaging studies suggestive of fatty liver
• biopsy consistent with the diagnosis of NAFLD

Exclusion Criteria:

• hepatic virus infections (HCV RNA-PCR negative)
• Hepatitis A, B, C, D, E and G
• cytomegalovirus and Epstein-Barr virus
• alcohol consumption
• history of parenteral nutrition
• use of drugs known to induce steatosis or to affect body weight and carbohydrate metabolism
• autoimmune liver disease, metabolic liver disease, Wilson's disease, and a-1-antitrypsin-associated liver disease were ruled out using standard clinical, laboratory and histological criteria