JAMA. 2019;321(3):256-265. doi:10.1001/jama.2018.20579 —
Schwimmer JB, Ugalde-Nicalo P, Welsh JA, et al.
determine the effects of a diet low in free sugars in adolescent boys with
- From 1988 to 2010, the prevalence of
nonalcoholic fatty liver disease (NAFLD) increased among children in the United
States. Pediatric NAFLD is more
common in boys than girls, and is now the most common liver disease in
- 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
- A total of 40 adolescent boys, ages 11-16, were
randomly assigned to either the intervention (low in free sugar) diet
group or the usual diet group in a 1:1 ratio. For the intervention diet
group, the target for free sugar intake was less than 3% of daily
calories, in order to align with the current World Health Organization
guidelines which recommend that daily free sugar intake is limited to less
than 10% for all people and to less than 5% in specific circumstances.
- The provided study diet was matched to the
reported baseline diet except for sugar content, and the use of artificial
sweeteners was prohibited. Participants
and their families were instructed not to purchase any food and to consume
only the food provided by the study staff.
- Study visits were conducted at baseline and at
4 and 8 weeks after initiation of the intervention. Demographic
information, as well as medical history, vital signs, anthropometric assessments,
and fasting blood collection for complete blood cell count, comprehensive
metabolic panel, lipid panel, liver panel, prothrombin time, and
international normalized ratio.
- The Nutrition Data System for Research was used
for the collection and analysis of 24-hour dietary recalls along with the
analysis of food records, menus, and recipes. Evaluation of each
participant’s diet was performed during the screening phase and between
study weeks 3 to 8.
- The primary outcome was change in percentage of
hepatic steatosis measured by MRI-PDFF in the intervention diet group
compared with change in the usual diet group over 8 weeks.
- The provision of a diet low in free sugars
compared with usual diet resulted in a greater reduction in hepatic
steatosis 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.
- At week 8, mean levels of ALT, aspartate
aminotransferase, and γ-glutamyl transpeptidasewere significantly lower in
the intervention diet group compared with the usual diet group after
adjusting for center and conditioning on baseline levels. The mean total
cholesterol level changed from 162 to 147mg/dL in the intervention diet
group and from 157 to 158 mg/dL in the usual diet group and there was a
significant adjusted mean between-group difference of −15.16mg/dL.
- There were no significant differences in
glucose, insulin, homeostasis model assessment for insulin resistance,
triglycerides, low-density lipoprotein cholesterol, or high-density
- This study demonstrated that a significant
improvement in hepatic steatosis could be achieved in adolescent boys with
NAFLD by restricting dietary sugars over 8 weeks.
- This clinical trial has shown that children and
families can follow a diet low in free sugars for up to 8 weeks when the
research team plans, purchases, and provides all meals. While this is not practical
to generalize widely, it shows that a low sugar diet reduces biomarkers of
NAFLD activity at least in the short term.
Points to Consider
- In the present study, the sample included
adolescent boys only, and the majority of the sample was Hispanic, thereby
limiting the generalizability of the findings.
- The intervention showed significant change,
but did not achieve reduction of hepatic steatosis or ALT level into the normal
range. Liver biopsies were not included
in this study and are needed to determine any changes in liver inflammation.
- It is unclear if data on the types of sugar
consumed at baseline and those consumes during the intervention were collected
and compared within and between groups. Therefore, it is unclear whether any
effect seen can be contributed to the amount of free sugar intake versus the