High triglyceride levels are increasingly recognized in children, particularly those who are overweight. There are no studies of treatment of high triglycerides in children and adolescents. Fish oil is attractive because it is considered safe and effective for treating high triglycerides in adults and has been used safely for other purposes in children. The investigators will conduct a randomized study of Lovaza (the only prescription omega-3 fish oil medication) in 44 children and adolescents to study efficacy in lowering triglycerides, safety, and possible mechanisms of beneficial effects.

Participants (n = 42, age 14 + 2 yrs) with hypertriglyceridemia and LDL cholesterol < 160 mg/dl were enrolled in a randomized double blind cross over trial comparing 4 g fish oil daily with placebo. Treatment interval was 8 weeks with a 4 week wash out, between the two treatment intervals. Lipid profile, lipoprotein particle distribution and size, glucose, insulin, high sensitivity C reactive protien (CRP), interleukin-6, fibrinogen, plasminogen activator inhibitor-1 (PAI-1), and thrombin generation were measured.

Patients were evaluated at 6 time points: Visit 1/baseline (week 0), Visit 2/randomization (week 4), Visit 3/after treatment 1 (week 12) , Visit 4/after wash out (week 16), Visit 5/after treatment 2 (week 24) and Visit 6/close out (week 28) . Patients were advised to maintain a stable diet and not alter baseline fish consumption . One participant took an oral contraceptive throughout the trial. Any fish oil supplements were discontinued. Advice on a heart healthy diet was provided. Blood pressure (right arm sitting with appropriate sized cuff, taken 3 times, last measurement used), height, and weight were measured at the beginning of the study, after the first wash out period, and close out. Participant phone contact was made during each treatment arm to assess diet stability. Fasting lipid profile was performed at every visit. Red blood cell fatty acid profile and secondary endpoints were performed at all visits except baseline.

Inclusion Criteria:

• Male or female patients who are 10-17 years of age
• Fasting triglyceride level >150 mg/dl and < 750 mg/dl measured on 2 separate occasions.
• Ability to follow the study procedures and adhere to the diet counseling recommendations
• Written parental permission and assent are obtained prior to any research procedures

Exclusion Criteria:

• Bleeding disorders
• Diabetes mellitus (impaired glucose tolerance is not an exclusion)
• Uncontrolled hypothyroidism
• Liver disease
• Allergy to fish/shellfish
• Patients requiring chronic use of aspirin and non-steroidal anti-inflammatory agents
• Patients requiring lipid lowering agents
• LDL-Cholesterol levels >160 mg/dl
• Current participation in another clinical study or within the previous 30 days
• Alcohol use
• Currently pregnant or planning to become pregnant during the course of this trial (confirmed by pregnancy testing)
• Any significant medical condition which the investigator believes would interfere with the patient's ability to safely participate in this trial

During the 20 week duration of the clinical trial. Specifically, during the first 8 week treatment period, the subsequent 4 week washout period, and the following 8 week treatment period.

Adverse Events were only collected and reported during the clinical trial, not after the conclusion of the trial, or prior to its start.

Intrinsic variability of triglycerides is large and may have confounded analyses; 4-week washout between treatment periods may have been too short; a reduction of triglycerides in the corn oil placebo group may have compromised the results.