Effects of whey protein on fatty liver, inflammationparameters and intestinal permeability in rats fed with a high-fat-highfructose diet

In recent years, the effects of various functional foods containing bioactive nutrients on the prevention and treatment of Non-Alcoholic Fatty Liver Disease (NAFLD), an important public health problem, have been one of the significant research topics. Whey proteins are rich in bioactive peptides and are known to have antioxidant and anti-inflammatory effects. This study aimed to test the hypothesis that whey protein supplementation with a high fat-high fructose diet would protect against liver damage, inflammation, endotoxemia, steatosis and intestinal permeability. To test this hypothesis, twelve-weeks-old male Wistar rats (n=36) were randomized into following 4 intervention groups for 8 weeks: high fat-high fructose diet group (Y), high fat-high fructose diet with whey protein isolate (WPI-200mg/kg/day) group (YW), control diet group (K), and control diet with whey protein isolate (200mg/kg/day) group (KW). To prepare the high fat-high fructose diet, a diet comprising 45,0% of energy from fat was provided, and fructose syrup was added to the drinking water at a concentration of 10,0%. Whey protein administration was performed with an oral gavage method for 8 weeks. Food and water consumption of the groups were recorded and anthropometric measurements were taken. Histological and immunohistochemical (Occludin and TLR-4 expression levels) analyzes were performed on liver, intestine and colon tissues. Biochemical analyses were performed for serum inflammatory markers (TNF- a and IL-6), liver enzyme activities (AST and ALT), lipid profile and endotoxin (LPS) levels. The abdominal circumference measurement and total liver damage score of the YW group (17,66 ± 0,33 cm and 9,11 ± 0,45) were found to be significantly lower compared to the Y group (18,77 ± 0,27 cm and (11,67 ± 0,33) (p<0,001). Lower liver damage scores were observed in the KW group (6,00 ± 0,74) compared to the YW group (9,11 ± 0,45) (p<0.001). Whey protein supplementation resulted in higher Occludin expression for the colon in the YW (2,89 ± 0,11) and KW (2,89 ± 0,11) groups compared to the Y (2,00 ± 0,23) and K (2,00 ± 1,67) groups (p<0,001). Similarly, Occludin expression in the small intestine was found to be higher in the YW (2,78 ± 0,14) and KW (2,78 ± 0,14) groups compared to the K group (2,00 ± 0,17) (p<0,05). No significant difference was observed for TNF-α, IL-6 and LPS levels between the groups (p>0,05). The results of this study suggest that whey protein supplementation may help ameliorate liver damage associated with high fat-high fructose diet and increase Occludin expression in the small intestine and colon in rats.