Dietary methionine restriction improves the gut microbiota and reduces intestinal permeability and inflammation in high-fat-fed mice.

Methionine-restricted diets (MRD) have been shown to prevent high fat diet (HFD) induced complications including fat accumulation, insulin sensitivity decrease, oxidative stress and inflammation increase. We hypothesized that intestinal microbiota changes may mediate these effects, and this study aims to prove this hypothesis. Mice were fed a normal diet (ND, 0.86% methionine + 4% fat), a HF diet (HFD, 0.86% methionine + 20% fat), or a MRD (0.17% methionine + 20% fat) and euthanized at week 22. Our results showed that the HFD induced fat accumulation and gut microbiota dysbiosis; reduced short-chain fatty acid (SCFA) production; and increased intestinal permeability, inflammatory response, and oxidative stress. The MRD decreased the body weight, body fat rate, and blood glucose and plasma lipid levels; increased the abundance of putative SCFA-producing bacteria Bifidobacterium, Lactobacillus, Bacteroides, Roseburia, Coprococcus, and Ruminococcus and inflammation-inhibiting bacteria Oscillospira and Corynebacterium; and decreased the abundance of inflammation-producing bacteria Desulfovibrio in colonic contents. Moreover, the MRD improved intestinal barrier function, inflammatory response, and oxidative stress, and altered the metabolite levels of colonic contents (such as increasing SCFA and bile acid concentrations); the latter may have contributed to the prevention of HFD-induced obesity. In conclusion, the MRD can improve gut health by regulating the intestinal microbiota and its metabolite profiles in the HFD mice. Reducing methionine intake by simple dietary adjustment may be an effective method to improve intestinal health in animals and humans.