Effect of dietary carnosine during in vitro digestion of a burger meal combo model including ascorbic acid as an antioxidant and fructose as a pro-oxidant

Abstract

Carnosine, as a meat constituent, was previously shown to exhibit some pro-oxidative effects during in vitro digestion of a burger meal model in the presence of high (supplemental) level of ascorbic acid (AA). In the current study, effects of dietary carnosine were assessed during in vitro digestion of a burger meal combo model, including intrinsic (low, LCar) and enriched (intermediate, MCar; high, HCar) carnosine in ground pork, with or without dietary levels of AA and/or fructose in simulated beverages. Increased levels of dietary carnosine (MCar and HCar) showed antioxidant activity, irrespective of the digestion phase and the presence of fructose and/or AA. At a dietary level, AA generally acted as an antioxidant, but promoted the formation of glyoxal (GO) in gastric digests and malondialdehyde (MDA) and hexanal in duodenal digests. Fructose generally showed a pro-oxidant effect, but decreased MDA and GO concentrations in both digestion phases. Despite a higher bio-accessible carnosine level measured in HCar, which potentially represents additional health benefits post absorption, MCar treatment provided optimal antioxidant activity during digestion without further effects obtained at the HCar level, showing a ceiling-like effect of dietary carnosine benefits in the digestive environment in vitro. These results demonstrate potential health advantages of increased carnosine in meat during digestion of a meal despite the presence of other redox-active dietary compounds and suggest a potential hormetic effect of carnosine can occur during digestion. PRACTICAL APPLICATION: Carnosine, a multifunctional compound naturally present in meat, can bring considerable advantages to meat consumers. Increased dietary levels of carnosine in meat reduced oxidation and the formation of advanced glycation end products (AGEs) during the digestion of a burger meal in the presence of dietary levels of either ascorbic acid (AA) (as an antioxidant) or fructose (as a pro-oxidant). In the context of this study, optimal benefits of carnosine were attained at the intermediate enhancement level, which can be naturally obtained through breeding and nutrition.

Keywords: carnosine; digestion; in vitro; oxidation; pork.