| Effect | Decrease |
| Values | mg/dl Mean and SD. Before 62.0 ±16.5, after 57.6 ± 13.7. |
| Trial Design | Non-controlled trial |
| Trial Length | 1-6 months |
| Number of Subjects | 20 |
| Sex | Both Genders |
Each day of this 8-week, uncontrolled open-label trial, 20 participants with major depressive disorder took 250 mg of theanine (suntheanine). 12 of the participants were receiving concurrent antidepression medication.Funding issues for this study:
Depression on the Hamilton Depression Rating Scale saw a notable reduction after 4 weeks that didn't continue to improve after 8. Trait, and almost state anxiety on the State-trait Anxiety Inventory were statistically significantly reduced as well. Sleep quality on the Pittsburgh Sleep Quality Index wasn' improved statistically significantly.
Performance on the Stroop test, both response time and error rate improved, and as did verbal memory and executive function on the Brief Assessment of Cognition in Schizophrenia survey, but not the others. HDL saw a statistically significant reduction, and AST, ALT, glutamyltranspeptidase, creatinine, BUN, HbA1c, triglycerides, LDL, and total cholesterol didn't see statistically significant changes.
"This study was supported by an Intramural Research
Grant (M.O. and H.K., grant number 24–11, 27–1)
for Neurological and Psychiatric Disorders of
National Center of Neurology and Psychiatry, and
an unrestricted research grant provided by the Taiyo
Kagaku Co. Ltd. H.O. and T.O. are employees of Taiyo Kagaku Co.
Ltd., which provided L-theanine tablets used in the
present study, and various food products."
