This outpatient feeding study will determine whether removal of all added sugars from the diet can slow or reverse progression of nonalcoholic fatty liver disease in adolescent children.
While some pediatricians have anecdotally observed that a sugar-restricted diet reverses nonalcoholic fatty liver disease in children and adolescents with this condition, insufficient evidence exists to support a shift in public health recommendations or the clinical guidelines that determine how most pediatricians treat such patients.
In this trial, 40 children with fatty liver disease will be randomized to follow either their usual diets, or a version of their regular diet devoid of all added sugars. Subjects on the reduced sugar diet will have all meals provided for them and their families alongside nutritional counseling and home visits from dietitians. Researchers will assess how liver fat content in both groups varies over time.
This study should provide the best evidence to date of whether removing added sugars from the diet affects liver fat content in adolescents, and thus inform our understanding of both the potential causes of and possible treatments for pediatric fatty liver disease. It will also provide unprecedented insight into the natural course of fatty liver disease, and serve as an essential step toward future trials investigating the role diet plays in fatty liver disease progression.
For most of the 20th century, physicians assumed that fatty liver and liver cirrhosis had two primary causes—either drinking too much alcohol or infection with the hepatitis B or C virus. This perspective has changed dramatically as the hospitals and physicians’ offices of this country have been confronted with an epidemic of patients with inflamed, fatty livers. In fact, in the more severe cases, their livers are almost indistinguishable from the livers of hardened alcoholics, although these patients rarely consume alcohol. Even more disturbing, this pattern of liver disease is now showing up in children, and the condition has even been diagnosed in infants less than a year old. These patients suffer from what is now referred to as nonalcoholic fatty liver disease or NAFLD, which is on pace to become the next metabolic epidemic in the country and perhaps around the world.
Today, the CDC estimates that one in five adult Americans—or 40 million adults—and one in ten adolescents—or 7 million children—have NAFLD.
Despite the prevalence and severity of the disease, research funding is limited. More American adults have NAFLD than prostate cancer, Alzheimer’s disease, type 2 diabetes, or even heart disease, and yet public funding for NAFLD research is only a fraction of what is allocated for these other conditions. And while a fatty liver does not kill as quickly as a heart attack, the long-term effects can be just as severe.
The evidence is compelling that the trigger of fatty liver disease is in the American diet, but the precise cause remains controversial. Because of the strong correlation between NAFLD and body weight—90% of the morbidly obese have fatty livers—many clinicians advise their patients to lose weight. Not surprisingly, this approach typically fails because people find it far easier to gain weight than to take it off and keep it off. Some physicians think eating too much fat causes NAFLD, and thus recommend low-fat diets to their patients. Still others, including many of the academic researchers studying NAFLD, believe that carbohydrates and added sugars, especially sucrose and high fructose corn syrup, are the primary dietary triggers for this diseases and recommend low-carbohydrate and low-sugar diets.
This study is designed as the first rigorously controlled experiment to test the effects of sugar restriction in children with fatty liver disease – and, by implication, provide insight into the role, if any, that sugar plays in NAFLD progression.
University of California, San Diego Medical Center
San Diego, California, 92103
Emory University School of Medicine
Atlanta, Georgia, 30322
Jeffrey Schwimmer, M.D. (Co-principal investigator)
Miriam Vos, M.D., MSPH (Co-principal investigator)
Jeffrey Schwimmer is a clinician and clinical researcher whose interests include the metabolic and behavioral factors associated with obesity, especially fatty liver disease in children. His research focuses on identifying the clinical predictors and correlates of pediatric NAFLD, the potential role of genes and familial factors in susceptibility to fatty liver, trials of potential pharmacological treatments for fatty liver disease, and investigation into the quality of life of children with obesity and NAFLD. Rady Children’s Hospital, where Dr. Schwimmer serves as Director of the Fatty Liver Clinic, is the first clinic in the United States dedicated to the care of children with fatty liver disease.
Miriam Vos is a clinician and clinical researcher whose interests include the effects of nutrition, especially fructose and other sugars, on fatty liver disease in children. Her research includes both large-scale surveys to quantify the diets of children with metabolic diseases and obesity, and clinical trials to test the effects of dietary manipulations on children with and without fatty liver disease. Her work has been reported in The New York Times, CNN, and many other major publications, and she is the author of The No-Diet Obesity Solution for Kids.