Schwimmer JB, et al. - In this randomized clinical trial, researchers investigated the effects of diet low in free sugars (those sugars added to foods and beverages and occurring naturally in fruit juices) in adolescent boys with nonalcoholic fatty liver disease (NAFLD). Adolescent boys with NAFLD with 8 weeks of provision of a diet low in free sugar content compared with usual diet had significant improvement in hepatic steatosis.

• Researchers undertook an open-label, 8-week randomized clinical trial of adolescent boys aged 11 to 16 years with histologically diagnosed NAFLD and evidence of active disease (hepatic steatosis >10% and alanine aminotransferase level ≥45 U/L) at 2 US academic clinical research centers from August 2015 to July 2017.
• The patients were randomized 1:1 to an intervention diet group or usual diet group; final date of follow-up was September 2017.
• Individualized menu planning and provision of study meals for the entire household to restrict free sugar intake to less than 3% of daily calories for 8 weeks were included in the intervention diet.
• They assessed diet adherence via twice-weekly telephone calls.
• The regular diet was consumed by usual diet participants.
• Change in hepatic steatosis estimated by magnetic resonance imaging proton density fat fraction measurement between baseline and 8 weeks was assessed as the primary outcome.
• They assumed the minimal difference of 4% as clinically important.
• Change in alanine aminotransferase level and diet adherence were included in the 12 secondary outcomes assessed.

• Researchers randomly assigned 40 adolescent boys to either the intervention diet group or the usual diet group (20 per group; mean [SD] age, 13.0 [1.9] years; most were Hispanic [95%]); all completed the trial.
• The intervention diet group (25% to 17%) displayed significantly greater mean decrease in hepatic steatosis from baseline to week 8 compared to the usual diet group (21% to 20%); the adjusted week 8 mean difference was −6.23% (95% CI, −9.45% to −3.02%; P < .001).
• Of the 12 prespecified secondary outcomes, they identified 7 as null and 5 as statistically significant; alanine aminotransferase level and diet adherence were included in the 5 statistically significant prespecified secondary outcomes.
• The intervention diet group had significantly greater geometric mean decrease in alanine aminotransferase level from baseline to 8 weeks (103 U/L to 61 U/L) than the usual diet group (82 U/L to 75 U/L); the adjusted ratio of the geometric means at week 8 was 0.65 U/L (95% CI, 0.53 to 0.81 U/L; P < .001).
• The intervention diet group had high adherence to the diet (18 of 20 reported intake of <3% of calories from free sugar during the intervention).
• No adverse events related to participation in the study were evident.