theanine and Diabetes-Mellitus--Type-2

l-Theanine (l-THE) is a nonproteinogenic amino acid derived from green tea (Camellia sinensis), which exhibits strong antioxidant-like properties and contributes to the favourable umami taste sensation. Several studies have reported that the consumption of this amino acid has many therapeutic effects, including improvements in brain and gastrointestinal function, cancer drug therapeutic efficacies, antihypertensive effects, and improved immune function. Considering the recent Western commercialisation and popularity of green tea consumption as a nootropic agent in humans, the aims of this review were to consolidate the existing knowledge from ex vivo and in vitro animal models and attempt to highlight the applicability of l-THE towards the human clinical trials. Considering the anti-inflammatory and antioxidants effects of l-THE presented in the current review, further research must translate the existing knowledge gained from animal and cell models to exploring the potential metabolic health benefits and moderating effects on the pathogenesis of conditions such as obesity, arthritis, depression, and type 2 diabetes in human trials. This will bridge the gap in literature and provide more insights into the mechanisms driving pathologies characterised by the inflammatory response and oxidative stress.

Topics: Animals; Antihypertensive Agents; Antioxidants; Brain; Camellia sinensis; Clinical Trials as Topic; Diabetes Mellitus, Type 2; Disease Models, Animal; Drug Evaluation, Preclinical; Glutamates; Humans; Oxidative Stress; Tea; Treatment Outcome

This study investigated the association between serum ethylamine levels as an indicator of l-theanine consumption and the development of type 2 diabetes in a Japanese community.. A total of 2,253 community-dwelling Japanese individuals aged 40-79 years without diabetes were monitored for 7 years. Serum ethylamine levels were divided into quartiles: ≤0.86, 0.87-2.10, 2.11-5.28, and ≥5.29 ng/mL. Kinetic analysis of serum ethylamine concentrations was performed after ingestion of l-theanine-rich green tea products containing 8 mg of l-theanine by 12 healthy volunteers.. Higher serum ethylamine was significantly associated with lower risk of the development of type 2 diabetes in a general Japanese population. The measurement of serum ethylamine concentration would be a useful biomarker for the objective estimation of l-theanine consumption.

Topics: Adult; Aged; Biomarkers; Diabetes Mellitus, Type 2; Drinking Behavior; Eating; Ethylamines; Female; Glutamates; Humans; Incidence; Insulin Resistance; Japan; Male; Middle Aged; Prediabetic State; Risk Factors; Tea