Nonalcoholic fatty liver disease (NAFLD) is a common and potentially serious form of chronic liver disease that occurs in patients who do not abuse alcohol. Present dietary recommendations for all Americans, including those with NAFLD, endorse a low-calorie, low-fat diet. However, little is known about the effect of diet composition on liver histopathology in patients with NAFLD. The aim of this study was to determine whether overall calorie intake and diet composition are associated with the severity of NAFLD histopathology. Seventy-four consecutive morbidly obese patients presenting for bariatric surgery from January 2001 to March 2002 were retrospectively reviewed. In addition to a standard surgical and psychological evaluation, all patients underwent a preoperative dietary evaluation using a standardized 24-hr food recall. Food intake was evaluated for total calories and macronutrients and compared to liver histopathology from biopsies routinely obtained during surgery. Associations with the severity of steatosis and the presence of inflammation or fibrosis were assessed separately using chi-square for categorical variables and ANOVA for continuous variables. Further, we conducted multiple logistic regression analyses for each histological outcome. There were no significant associations between either total caloric intake or protein intake and either steatosis, fibrosis, or inflammation. However, higher CHO intake was associated with significantly higher odds of inflammation, while higher fat intake was associated with significantly lower odds of inflammation. In conclusion, present dietary recommendations may worsen NAFLD histopathology.

Breath biomarkers have the potential to offer information that is similar to conventional clinical tests or they are entirely unique. Preliminary data support the use of breath biomarkers in the study of liver disease, in particular non-alcoholic fatty liver disease (NAFLD). It was evaluated whether breath ethanol, ethane, sulfur compounds and acetone would be associated with hepatic histopathology amongst morbidly obese patients presenting for bariatric surgery. Breath samples were collected during a preoperative visit and compared with liver biopsies obtained during the surgery. A Student's two-tailed t-test was used to compare differences between the two groups. Linear regression was used to analyse associations between the concentrations of breath molecules and independent predictor variables. It was found that breath ethanol, ethane and acetone can be useful biomarkers in patients with NAFLD. In particular, breath ethanol can be associated with hepatic steatosis, and breath acetone can be associated with non-alcoholic steatohepatitis.

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