Dietary methionine restriction improved the intestinal microbiota composition, barrier function, oxidative stress, and inflammation in high-fat-fed mice.

Scope: Reduced digestibility of foods containing oxidized proteins and the subsequent excessive accumulation of undigested components in the colon may cause changes in the intestinal flora composition. This study evaluates the characteristics of this change and the potential adverse effects on organisms. Methods and results: Pork is cooked using sous-vide or at high temperature and pressure (HTP), then freeze-dried, resulting in different levels of oxidized damage. Mice are fed diets containing low-(LOP), medium-(MOP), or high-oxidative damage pork (HOP) for 12 weeks. HOP intake increases mice body weight, induces inflammatory response, and causes oxidative stress, as indicated by the accumulation of oxidative products. Increased serum LPS levels and downregulation of tight junction-related genes in the mucosa suggest mucosal barrier damage. Alterations in the cecal microbiota include reduced relative abundance of the mucin-degrading bacteria Akkermansia, beneficial bacteria Lactobacillus and Bifidobacterium, and H 2 S-producing bacteria Desulfovibrio and increased relative abundance of the pro-inflammatory bacteria Escherichia-Shigella and pathobiont Mucispirillum.

BACKGROUNDChanges in antioxidant activity of fruit during fermentation are related to changes in the composition of phenolic acids and flavonoids. In this study, we investigated the effects of Lactobacillus plantarum on the phenolic profile, antioxidant activities, and metabolites of kiwifruit pulp.RESULTSLactobacillus plantarum fermentation increased scavenging activity of 1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,20‐azinobis (3‐ethylbenzothiazoline‐6‐sulphonic acid) diammonium salt (ABTS) radicals. The content of phenolics and flavonoids was increased after fermentation. Correlation analysis demonstrated that the phenolic and flavonoid content was responsible for increasing the scavenging activities of DPPH and ABTS. Lactobacillus plantarum influenced the phenolic profile of the pulp. Protocatechuic and chlorogenic acids were the predominant phenolic acids in fermented kiwifruit pulp. Gallic acid, chlorogenic acid, epicatechin, and catechins were degraded by L. plantarum. The content of 6,7‐dihydroxy coumarin and p‐coumaric acid, and especially protocatechuic acid, was increased by fermentation. Metabolic differences in lactic acid, fructose, phosphoric acid, gluconolactone, and sugar were evident between non‐fermented and fermented kiwifruit.CONCLUSIONLactobacillus plantarum fermentation increased antioxidant compounds and antioxidant activity in kiwifruit pulp. These results provide the foundation to target the functional benefits of L. plantarum‐fermented kiwifruit pulp for further human, animal, and plant health applications. © 2020 Society of Chemical Industry

This study aims to investigate the health effects of long-term dietary oxidized tyrosine (O-Tyr) and its main product (dityrosine) administration on mice metabolism. Mice received daily intragastric administration of either O-Tyr (320 μg/kg body weight), dityrosine (Dityr, 320 μg/kg body weight), or saline for consecutive 6 weeks. Urine and plasma samples were analyzed by NMR-based metabolomics strategies. Body weight, clinical chemistry, oxidative damage indexes, and histopathological data were obtained as complementary information. O-Tyr and Dityr exposure changed many systemic metabolic processes, including reduced choline bioavailability, led to fat accumulation in liver, induced hepatic injury, and renal dysfunction, resulted in changes in gut microbiota functions, elevated risk factor for cardiovascular disease, altered amino acid metabolism, induced oxidative stress responses, and inhibited energy metabolism. These findings implied that it is absolutely essential to reduce the generation of oxidation protein products in food system through improving modern food processing methods.

Dietary methionine restriction reduces hepatic steatosis and oxidative stress in high-fat-fed mice by promoting H2S production.

Dietary methionine restriction improves impairment of learning and memory function induced by obesity, likely by increasing H2S production.

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The findings suggested that decreased insulin secretion triggered by OTPs may be mediated by oxidative stress and mitochondrial damage in pancreatic β cells.