Relationship Between Protein Intake and Sarcopenia in the Elderly with Nonalcoholic Fatty Liver Disease Based on the Fourth and Fifth Korea National Health and Nutrition Examination Survey

Background: The association between sarcopenia and protein intake has been well studied. However, limited data are available on the association between sarcopenia and protein intake in people with nonalcoholic fatty liver disease (NAFLD). This study aimed to investigate the association between protein intake and sarcopenia among elderly participants with NAFLD using the Korea National Health and Nutrition Examination Survey (KNHANES). Methods: Data of 4179 participants (1576 men and 2603 women, age ≥60 years) who participated in the KNHANES during 2008-2011 were obtained. Sarcopenia was defined as appendicular skeletal muscle mass/wt (%) of 1 standard deviation below the gender-specific mean for healthy adults and NAFLD as liver fat score using the fatty liver prediction models. According to their daily protein intake, participants were grouped into the high protein intake group (>1.2 g/kg/day), middle protein intake group (0.8-1.2 g/kg/day), and low protein intake group (<0.8 g/kg/day). Generalized linear models and logistic regression models were used. Results: The overall prevalence of sarcopenia in participants with NAFLD was 16.53%. Compared with the highest protein intake group, the low protein intake group had a significantly higher risk of sarcopenia (adjustment odds ratio = 1.707; 95% confidence interval = 1.009-2.886). In the fully adjusted model, the highest protein intake group had significantly lower levels of insulin, total body fat, vitamin B, and fat intake, whereas muscle proportions, energy, carbohydrates, vitamin A, and vitamin C intake of high protein intake participants were significantly higher than other groups. Conclusion: The prevalence of sarcopenia and sarcopenia-related factors were significantly lower in NAFLD elderly participants with high protein intake. These results suggest that high protein intake can help prevent and manage sarcopenia in people with NAFLD.