Oral L-theanine administration promotes fat browning and prevents obesity in mice fed high-fat diet associated with the modulation of gut microbiota

L-theanine (LTh), a unique nonproteinic amino acid of tea, is known to possess beneficial effects on diet-induced obesity. This study aimed to evaluate whether orally administrated LTh could improve the adaptive thermogenesis of high-fat diet (HFD)-induced obese mice through regulating the composition of gut microbiota. Mice were fed control diet or a HFD with or without LTh for 12 weeks. Oral LTh administration ameliorated adiposity and hepatic steatosis in HFD mice. LTh increased the metabolic activities of brown fat and subcutaneous white fat by enhancing the expression of a series of thermogenic genes. More importantly, LTh improved the intestinal dysbiosis by decreasing the ratio of Firmicutes/Bacteroidetes, along with increases in the fecal short chain fatty acids concentrations. In conclusion, LTh ameliorates metabolic features of obesity by promoting fat browning and improving gut microbiota composition in HFD mice, which may be a mechanism of LTh-induced beneficial metabolic health.

Automated summary

The study showed that L-theanine can improve metabolic features of obesity in high-fat diet-induced obese mice by promoting fat browning and improving gut microbiota composition.