A recent randomized study (Jeffrey B. Schwimmer, MD1,2; Patricia Ugalde-Nicalo, MD1; Jean A. Welsh, PhD, MPH, RN3,4,5; et al JAMA. 2019;321(3):256-265. doi:10.1001/jama.2018.20579) examined the beneficial effects of a low free sugar diet for Nonalcoholic Fatty Liver Disease (NAFLD) in adolescent boys. Congratulations to the authors, particularly to Miriam Vos (my Emory colleague & corresponding author) and Jeffrey Schwimmer (whose training overlapped with mine in Cincinnati).
“In this randomized clinical trial that included 40 adolescent boys aged 11 to 16 years with nonalcoholic fatty liver disease followed up for 8 weeks, provision of a diet low in free sugars compared with usual diet resulted in a greater reduction in hepatic steatosis [based on MRI] from 25% to 17% in the low free sugar diet group and from 21% to 20% in the usual diet group, a statistically significant difference of −6.23% when adjusted for baseline.”
Summary of this study in NY Times: To Fight Fatty Liver, Avoid Sugary Foods and Drinks
An excerpt from NY Times:
To make the diet easier and more practical for the children in the limited-sugar group to follow, the researchers asked their families to follow it as well. They tailored the diet to the needs of each household by examining the foods they consumed in a typical week and then swapping in lower sugar alternatives. If a family routinely ate yogurts, sauces, salad dressings and breads that contained added sugar, for example, then the researchers provided them with versions of those foods that did not have sugar added to them.
Fruit juices, soft drinks and other sweet drinks were forbidden. They were replaced with unsweetened iced teas, milk, water and other nonsugary beverages. Dietitians prepared and delivered meals to the families twice a week, which helped them stick to their programs.
Importance Pediatric guidelines for the management of nonalcoholic fatty liver disease (NAFLD) recommend a healthy diet as treatment. Reduction of sugary foods and beverages is a plausible but unproven treatment.
Objective To determine the effects of a diet low in free sugars (those sugars added to foods and beverages and occurring naturally in fruit juices) in adolescent boys with NAFLD.
Design, Setting, and Participants 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) randomized 1:1 to an intervention diet group or usual diet group at 2 US academic clinical research centers from August 2015 to July 2017; final date of follow-up was September 2017.
Interventions The intervention diet consisted of 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. Twice-weekly telephone calls assessed diet adherence. Usual diet participants consumed their regular diet.
Main Outcomes and Measures The primary outcome was change in hepatic steatosis estimated by magnetic resonance imaging proton density fat fraction measurement between baseline and 8 weeks. The minimal clinically important difference was assumed to be 4%. There were 12 secondary outcomes, including change in alanine aminotransferase level and diet adherence.
Results Forty adolescent boys were randomly assigned 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%]) and all completed the trial. The mean decrease in hepatic steatosis from baseline to week 8 was significantly greater for the intervention diet group (25% to 17%) vs the usual diet group (21% to 20%) and the adjusted week 8 mean difference was −6.23% (95% CI, −9.45% to −3.02%; P < .001). Of the 12 prespecified secondary outcomes, 7 were null and 5 were statistically significant including alanine aminotransferase level and diet adherence. The geometric mean decrease in alanine aminotransferase level from baseline to 8 weeks was significantly greater for the intervention diet group (103 U/L to 61 U/L) vs the usual diet group (82 U/L to 75 U/L) and 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). Adherence to the diet was high in the intervention diet group (18 of 20 reported intake of <3% of calories from free sugar during the intervention). There were no adverse events related to participation in the study.
Conclusions and Relevance In this study of adolescent boys with NAFLD, 8 weeks of provision of a diet low in free sugar content compared with usual diet resulted in significant improvement in hepatic steatosis. However, these findings should be considered preliminary and further research is required to assess long-term and clinical outcomes.
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