The interaction between the gut microbiota and dietary carbohydrates in nonalcoholic fatty liver disease.

Imbalance between fat production and consumption causes various metabolic disorders. Nonalcoholic fatty liver disease (NAFLD), one such pathology, is characterized by abnormally increased fat synthesis and subsequent fat accumulation in hepatocytes1,2. While often comorbid with obesity and insulin resistance, this disease can also be found in lean individuals, suggesting specific metabolic dysfunction2. NAFLD has become one of the most prevalent liver diseases in adults worldwide, but its incidence in both children and adolescents has also markedly increased in developed nations3,4. Progression of this disease into nonalcoholic steatohepatitis (NASH), cirrhosis, liver failure, and hepatocellular carcinoma in combination with its widespread incidence thus makes NAFLD and its related pathologies a significant public health concern. Here, we review our understanding of the roles of dietary carbohydrates (glucose, fructose, and fibers) and the gut microbiota, which provides essential carbon sources for hepatic fat synthesis during the development of NAFLD. Evidence is emerging of a role for interactions between gut microbes and dietary carbohydrates in non-alcoholic fatty liver disease (NAFLD), one of the most prevalent liver disorders of adults worldwide, with children and adolescents also increasingly affected. NAFLD can progress into even more serious conditions such as steatohepatitis, cirrhosis, liver cancer and liver failure. Researchers led by Cholsoon Jang at the University of California Irvine review understanding of the role of dietary glucose, fructose, fiber and gut microbial metabolism in contributing to NAFLD. The involvement of gut microbes in hepatic assimilation of carbohydrates into fatty acids that accumulate in NAFLD indicates possible treatment strategies based on interfering with microbial metabolism. New understanding of the interactions between carbohydrate metabolism and gut microbes will also help reveal why some people develop NAFLD and suggest appropriate preventive interventions.