Fructose and Liver Diseases in Youth: Help Them FLY

Study Rationale: Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease estimated to occur in 10-20% of obese children and adults. High fructose and saturated fat intakes are thought to be major dietary factors contributing to over nutrition, insulin resistance, cardio-metabolic risk (e.g dysplipidemia, hypertension) and disease pathogenesis in adults and children with NAFLD . Although weight loss is the goal of treatment, there are currently no evidence based clinical guidelines regarding the specific dietary treatment needed for NAFLD. The investigator has shown previously that children and adolescents with NAFLD have diets rich in both total fructose (\>10% of total energy intake) and high fructose corn syrup (20-50% of total fructose intake. These levels of intake were associated with increasing indices of liver dysfunction, insulin resistance and inflammation. In a recent pilot study, the investigator has showed that children with NAFLD experienced significant reductions in systolic blood pressure, percentage body fat, plasma markers of liver dysfunction (ALT, AST), cardio-metabolic risk (HOMA-IR, AI-IR, TG, Apo-B100) and alterations in body fat distribution in response to six months of an iso-caloric/low fructose diet (\~5% of total kcal). High levels of fructose in the diet have been independently associated with insulin resistance, visceral adiposity, hepatic and skeletal muscle intramyocellular fat (IMF) deposition, altered hepatic mitochondrial function and energy utilization (ATP depletion), increased rates of de novo lipogenesis, inflammation, and hepatic fibrosis in both animal models and adults with NAFLD. While adult studies in NAFLD have related the impact of high intakes of HFCS to altered liver energetics (ATP production) and increasing insulin resistance and IMF , this has not be studied in obese children and adolescents with NAFLD. In addition, no information is available regarding the impact of dietary fructose reductions on these processes in either obese children, adolescents or adults with NAFLD. The plan is to use validated, non-invasive and safe methodologies such as Magnetic Resonance Imaging (MRI) and Magnetic Resonance Stimulation (MRS) to compare and contrast the effects of varying fructose intakes (low vs high) in iso-caloric diets on liver mitochondrial energetic (ATP production), hepatic and skeletal muscle fat content and markers of cardio-metabolic risk, liver dysfunction, insulin resistance, inflammation and oxidative stress in adolescents with NAFLD.

Hypotheses

1. Obese adolescents with NAFLD treated with a low fructose /low HFCS diet over 12 weeks, in the absence of weight loss, will result in significant improvements in indices of hepatic ATP production and reduced liver/ skeletal muscle fat deposition when compared to the effects of a higher fructose/higher HFCS diet. 2. Obese adolescents with NAFLD treated with a low fructose /low HFCS diet over 12 weeks, in the absence of weight loss, will result in significant improvements in indices of visceral and subcutaneous adiposity, insulin resistance and markers of liver and cardio-metabolic dysfunction, inflammation and oxidative stress when compared to the effects of a higher fructose/higher HFCS diet.

• Change in hepatic intramyocellular surface area in response to dietary intervention. [Срок оценки: Change from baseline to 3 months]
• Change in visceral adipose tissue (VAT cm3/ht2) and subcutaneous adipose tissue (SAT cm3/ht2) surface area in response to the dietary intervention [Срок оценки: Change from baseline to 3 months]
• Change in markers of liver dysfunction in response to the dietary intervention [Срок оценки: Change from baseline to 3 months]
• Change in cardio-metabolic risk factors in response to the dietary intervention [Срок оценки: Change from baseline to 3 months]
• Change in measures of insulin resistance in response to the dietary intervention [Срок оценки: Change from baseline to 3 months]