Almost 40% of obese Hispanic children and adolescents are estimated to have non-alcoholic fatty liver disease (NAFLD). Very few studies have examined the efficacy of treatment strategies for reducing elevated liver fat (ELF), with no studies in Hispanic children and adolescents. Consequently, there are no specific guidelines for treating pediatric NAFLD or reducing ELF other than general advice for weight loss. In addition, a recent genome-wide association study in adults identified a variant in the PNPLA3 gene as a novel factor explaining increased liver fat in Hispanics, but there are no studies that have evaluated the efficacy of treatments for ELF as a function of PNPLA3 genotype. In preliminary data, we show that obese Hispanic children and adolescents who carry the GG genotype of PNPLA3: a) have > 2-fold higher liver fat compared to CC and CG individuals; and b) are more susceptible to liver fat accumulation in the context of high dietary sugar. This latter finding fit with a recently published study in mice and our current, though limited, understanding of the function and regulation of PNPLA3. Taken together, these observations suggest that different dietary strategies may have differential effects on reducing liver fat, depending on PNPLA3 genotype. Therefore, our overall objective is to identify novel interventions that target the mechanism of fat deposition in liver rather than rely on weight loss, which is typically difficult o achieve and challenging to sustain. We therefore propose to conduct a randomized trial to test the efficacy of dietary sugar reduction for improving liver fat content in obese Hispanic children and adolescents and examine whether the effects of this approach vary by PNPLA3 genotype. We will recruit 120 Hispanics (10-18 years) with clinically diagnosed NAFLD and randomize them to 16-week interventions under weight stable conditions: 1) standard of care advice for healthy eating (control/placebo group); and 2) reduction of dietary sugars (treatment group). The following will be measured before and after intervention: total liver fat, liver fibrosis, visceraland subcutaneous abdominal adipose tissue volume by magnetic resonance imaging methods at 3 Tesla; total body fat by DEXA; plasma liver enzymes, fasting insulin, glucose, lipids, free fatty acids, and inflammatory markers, and insulin and glucose response to an oral glucose challenge. The hypotheses are: a) liver fat content and metabolic outcomes, such as lipids and inflammatory biomarkers, will show significantly greater improvements with sugar reduction relative to control; and b) greater benefits in liver fat reduction and metabolic outcomes will be observed in GG subjects relative to CC/CG individuals. These results will provide efficacy data for a novel treatment strategy for ELF in obese Hispanic children and adolescents and has the potential to impact personalized dietary recommendations for treatment and prevention of NAFLD in Hispanics, as a function of genetic predisposition.

Public Health Relevance

Currently used strategies to reduce elevated liver fat (ELF) are inadequate to address this emerging public health problem. This is particularly relevant in Hispanics who are highly susceptible to ELF, in part due to genetic predisposition. This project will carry out a nutrigenetic intervention focused on reducing dietary sugar as an effective strategy to decreasing ELF in Hispanics. The results of this study could potentially impact personalized dietary recommendations for treating excess liver fat content as a function of genetic predisposition.

National Institute of Health (NIH)
National Institute on Minority Health and Health Disparities (NIMHD)
Research Project (R01)
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Kidney, Nutrition, Obesity and Diabetes Study Section (KNOD)
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Rajapakse, Nishadi
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University of Southern California
Public Health & Prev Medicine
Schools of Medicine
Los Angeles
United States
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Hartiala, Jaana; Schwartzman, William S; Gabbay, Julian et al. (2017) The Genetic Architecture of Coronary Artery Disease: Current Knowledge and Future Opportunities. Curr Atheroscler Rep 19:6
Barrington, William T; Salvador, Anna C; Hartiala, Jaana A et al. (2017) Proceedings of the 11th Congress of the International Society of Nutrigenetics and Nutrigenomics (ISNN 2017). J Nutrigenet Nutrigenomics 10:155-162