theanine and Obesity

Tea has been a very popular beverage around the world for centuries. The reason that it is delicious, enabling hydration, showing warming and relaxing effect can be mentioned why it is consumed so much in addition to its prominent health effects. Although the catechins and caffeine are the primary bioactive components that are related with the health effects of the tea, the health effects of theanine amino acid, which is a nonproteinic amino acid special to tea, has become prominent in recent years. It has been known that the theanine amino acid in tea has positive effects especially on relaxing, cognitive performance, emotional status, sleep quality, cancer, cardiovascular diseases, obesity, and common cold. The results of acute and chronic toxicity tests conducted on the safety of theanine express that L-theanine is reliable in general even if it is consumed too much with diet. However, it has not revealed a clear evidence-based result yet regarding theanine metabolism, health effects, and its safety. Within this frame, chemical structure of theanine, its biosynthesis, dietary sources, metabolism, health effects, and safety are discussed in present study.

Topics: Cardiovascular Diseases; Cognition; Glutamates; Humans; Neoplasms; Obesity; Plant Leaves; Randomized Controlled Trials as Topic; Sleep; Stress, Physiological; Tea

l-Theanine is a nonprotein amino acid with much beneficial efficacy. We found that intraperitoneal treatment of the mice with l-theanine (100 mg/kg/day) enhanced adaptive thermogenesis and induced the browning of inguinal white adipose tissue (iWAT) with elevated expression of Prdm16, Ucp1, and other thermogenic genes. Meanwhile, administration of the mice with l-theanine increased energy expenditure. In vitro studies indicated that l-theanine induced the development of brown-like features in adipocytes. The shRNA-mediated depletion of Prdm16 blunted the role of l-theanine in promoting the brown-like phenotypes in adipocytes and in the iWAT of mice. l-theanine treatment enhanced AMPKα phosphorylation both in adipocytes and iWAT. Knockdown of AMPKα abolished l-theanine-induced upregulation of Prdm16 and adipocyte browning. l-Theanine increased the α-ketoglutarate (α-KG) level in adipocytes, which may increase the transcription of Prdm16 by inducing active DNA demethylation on its promoter. AMPK activation was required for l-theanine-induced increase of α-KG and DNA demethylation on the Prdm16 promoter. Moreover, intraperitoneal administration with l-theanine ameliorated obesity, improved glucose tolerance and insulin sensitivity, and reduced plasma triglyceride, total cholesterol, and free fatty acids in the high-fat diet-fed mice. Our results suggest a potential role of l-theanine in combating diet-induced obesity in mice, which may involve l-theanine-induced browning of WAT.

Topics: Adipose Tissue, White; AMP-Activated Protein Kinases; Animals; Diet, High-Fat; DNA Methylation; DNA-Binding Proteins; Glutamates; Ketoglutaric Acids; Maillard Reaction; Male; Mice, Inbred C57BL; Obesity; Transcription Factors