Losartan for the Treatment of Pediatric NAFLD

Inclusion Criteria: * Age 8-17 years at initial screening interview * Histological evidence of NAFLD with or without fibrosis and a NAFLD activity score (NAS) of ≥3, on a liver biopsy obtained no more than 730 days prior to enrollment. * Serum ALT at screening ≥ 50 IU/L Exclusion Criteria: * Body weight less than 70 kg or greater than 150 kg at screening * Significant alcohol consumption or inability to reliably quantify alcohol intake * Use of drugs historically associated with NAFLD (amiodarone, methotrexate, systemic glucocorticoids, tetracyclines, tamoxifen, estrogens at doses greater than those used for hormone replacement, anabolic steroids, valproic acid, other known hepatotoxins) for more than 2 consecutive weeks in the past year prior to randomization * New treatment with vitamin E or metformin started in the past 90 days or plans to alter the dose or stop over the next the 24 weeks. A stable dose is acceptable. * Prior or planned bariatric surgery * Uncontrolled diabetes (HbA1c 9.5% or higher) * Presence of cirrhosis on liver biopsy * History of hypotension or history of orthostatic hypotension * Stage 2 Hypertension or \>140 systolic or \>90 diastolic at screening * Current treatment with any antihypertensive medications including all angiotensin converting enzyme (ACE) inhibitors or aliskiren * Current treatment with potassium supplements or any drug known to increase potassium * Current daily use of nonsteroidal anti-inflammatory drugs (NSAIDs) * Current treatment with lithium * Platelet counts below 100,000 /mm3 * Clinical evidence of hepatic decompensation (serum albumin \< 3.2 g/dL, international normalized ratio (INR) \>1.3, direct bilirubin \>1.3 mg/dL, history of esophageal varices, ascites, or hepatic encephalopathy) * Evidence of chronic liver disease other than NAFLD: * Biopsy consistent with histological evidence of autoimmune hepatitis * Serum hepatitis B surface antigen (HBsAg) positive. * Serum hepatitis C antibody (anti-HCV) positive. * Iron/total iron binding capacity (TIBC) ratio (transferrin saturation) \> 45% with histological evidence of iron overload * Alpha-1-antitrypsin (A1AT) phenotype/genotype ZZ or SZ * Wilson's disease * Serum alanine aminotransferase (ALT) greater than 300 IU/L * History of biliary diversion * History of kidney disease and/or estimated glomerular filtration rate (eGFR) \< than 60 mL/min/1.73 m2 using Schwartz Bedside GFR Calculator for Children isotope dilution mass spectroscopy (IDMS)-traceable * Known Human Immunodeficiency Virus (HIV) infection * Active, serious medical disease with life expectancy less than 5 years * Active substance abuse including inhaled or injected drugs, in the year prior to screening * Pregnancy, planned pregnancy, potential for pregnancy and unwillingness to use effective birth control during the trial, breast feeding * Participation in an investigational new drug (IND) trial in the 150 days prior to randomization * Any other condition which, in the opinion of the investigator, would impede compliance or hinder completion of the study * Inability to swallow capsules * Known allergy to losartan potassium or other angiotensin receptor blocker * Failure of parent or legal guardian to give informed consent or subject to give informed assent