Objective  To investigate the effect of dietary naked oat (Avena nuda L.) oligopeptides (OOPs) on dyslipidemia and the mechanism of the effect in rats.

  Methods  A total of 100 healthy specific pathogen free (SPF) male Sprague-Dawley rats, 90 were fed with high-fat diet for 8 weeks to establish an animal model of dyslipidemia and 10 with normal diet as the blank controls. The two thirds of the model rats with higher total cholesterol (TC) were randomly divided into 6 groups (10 in each group): a model control group (with distilled water), a whey protein group (with 0.692 g/kg body weight whey protein in drinking water), and 4 OOPs groups (with OOPSs of 0.173, 0.346, 0.692, and 1.385 g/kg body weight in drinking water). The treatments continued for 13 weeks. Serum TC, triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), aspartate transaminase (AST), alanine aminotransferase (ALT), superoxide dismutase (SOD), and malondialdehyde (MDA) were determined at week 0, 4, 8, and the end of the treatments for the rats of various groups.

  Results  Mixed dyslipidemia rat model was successfully established after 8-week high-fat diet intervention. Compared with those in the model and whey protein control rats, significantly lower serum TC (0.40, 0.66, 0.61, 0.58 mmol/L), TG (0.23, 0.20, 0.14, 0.16 mmol/L), and LDL-C (0.36, 0.42, 0.41, 0.41 mmol/L) in the 4-group OOPs rats were detected at the end of treatments (P < 0.05 for all); in addition, significantly reduced serum AST, ALT and MDA but increased SOD were measured in the OOPs rats in comparison with those in the model control rats (all P < 0.05).

  Conclusion  Naked oat oligopeptides could effectively improve lipid metabolism and liver function and the effects may be related to the regulation of oxidative stress in dyslipidemic rats.