58 Published Research Papers on Arctic Composure’s Ingredients

L‑Theanine — 39 Human Research Publications

Including 21+ clinical trial reports.

Stress, attention and cognition in healthy adults (clinical trials) 21 publications

1. L‑Theanine reduces psychological and physiological stress responses (2007) – Kimura, K. et al. Biological Psychology, 74(1), 39–45.
2. Anti‑stress effect of theanine on students during pharmacy practice: positive correlation among salivary α‑amylase activity, trait anxiety and subjective stress (2013) – Unno, K. et al. Pharmacology, Biochemistry and Behavior, 111, 128–135.
3. Effects of L‑Theanine Administration on Stress‑Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial (2019) – Hidese, S. et al. Nutrients, 11(10), 2362.
4. A Randomized, Triple‑Blind, Placebo‑Controlled, Crossover Study to Investigate the Efficacy of a Single Dose of AlphaWave® L‑Theanine on Stress in a Healthy Adult Population (2021) – Evans, M. et al. Neurology and Therapy, 10(2), 1061–1078.
5. Effects of L‑Theanine on Cognitive Function in Middle‑Aged and Older Subjects: A Randomized Placebo‑Controlled Study (2021) – Baba, Y. et al. Journal of Medicinal Food, 24(4), 333–341.
6. The effects of L‑theanine, caffeine and their combination on cognition and mood (2008) – Haskell, C. F. et al. Biological Psychology, 77(2), 113–122.
7. A double‑blind, placebo‑controlled study evaluating the effects of caffeine and L‑theanine both alone and in combination on cerebral blood flow, cognition and mood (2015) – Dodd, F. L. et al. Psychopharmacology, 232(14), 2563–2576.
8. Effects of L‑theanine or caffeine intake on changes in blood pressure under physical and psychological stresses (2012) – Yoto, A. et al. Journal of Physiological Anthropology, 31(1), 28.
9. Effect of Combined Ingestion of L‑Theanine and L‑Arginine for Short‑Term Psychological Stress in Young Adults: A Randomized Placebo‑Controlled Study (2022) – Furushima, D. et al. Journal of Nutritional Science and Vitaminology, 68(6), 540–546.
10. Dose‑response effect of L‑theanine on psychomotor speed, sustained attention, and inhibitory control: a double‑blind, placebo‑controlled, crossover study (2023) – Dassanayake, T. L. et al. Nutritional Neuroscience, 26(11), 1138–1146.
11. L‑Theanine and caffeine improve target‑specific attention to visual stimuli by decreasing mind wandering: a human functional magnetic resonance imaging study (2018) – Kahathuduwa, C. N. et al. Nutrition Research, 49, 67–78.
12. Caffeine and theanine exert opposite effects on attention under emotional arousal (2017) – Giles, G. E. et al. Canadian Journal of Physiology and Pharmacology, 95(1), 93–100.
13. Acute effects of theanine, caffeine and theanine‑caffeine combination on attention (2017) – Kahathuduwa, C. N. et al. Nutritional Neuroscience, 20(6), 369–377.
14. Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task (2012) – Foxe, J. J. et al. Neuropharmacology, 62(7), 2320–2327.
15. L‑theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha‑band activity and attention task performance (2008) – Kelly, S. P. et al. Journal of Nutrition, 138(8), 1572S–1577S.
16. Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together (2008) – Rogers, P. J. et al. Psychopharmacology, 195(4), 569–577.
17. The acute effects of L‑theanine in comparison with alprazolam on anticipatory anxiety in humans (2004) – Lu, K. et al. Human Psychopharmacology, 19(7), 457–465.
18. Anti‑Stress, Behavioural and Magnetoencephalography Effects of an L‑Theanine‑Based Nutrient Drink: A Randomised, Double‑Blind, Placebo‑Controlled, Crossover Trial (2016) – White, D. J. et al. Nutrients, 8(1), 53.
19. The combined effects of L‑theanine and caffeine on cognitive performance and mood (2008) – Owen, G. N. et al. Nutritional Neuroscience, 11(4), 193–198.
20. L‑theanine and caffeine improve task switching but not intersensory attention or subjective alertness (2010) – Einöther, S. J. et al. Appetite, 54(2), 406–409.
21. Reduced Stress and Improved Sleep Quality Caused by Green Tea Are Associated with a Reduced Caffeine Content (2017) – Unno, K. et al. Nutrients, 9(7), 777.

Brain activity and physiological mechanisms 6 publications

1. L‑テアニンのヒトの脳波に及ぼす影響 [English title: Effects of L‑Theanine on the Release of α‑Brain Waves in Human Volunteers] (1998) – Kobayashi, K. et al. Nippon Nōgeikagaku Kaishi, 72(2), 153–157.
2. L‑theanine improves neurophysiological measures of attention in a dose‑dependent manner: a double‑blind, placebo‑controlled, crossover study (2022) – Dassanayake, T. L. et al. Nutritional Neuroscience, 25(4), 698–708.
3. Effect of L‑theanine on sensorimotor gating in healthy human subjects (2014) – Ota, M. et al. Psychiatry and Clinical Neurosciences, 68(5), 337–343.
4. L‑theanine, a natural constituent in tea, and its effect on mental state (2008) – Nobre, A. C. et al. Asia Pacific Journal of Clinical Nutrition, 17(Suppl 1), 167–168.
5. The deployment of intersensory selective attention: a high‑density electrical mapping study of the effects of theanine (2007) – Gomez‑Ramirez, M. et al. Clinical Neuropharmacology, 30(1), 25–38.
6. Effects of single‑dose L‑theanine on motor cortex excitability (2021) – Yuan, S. et al. Clinical Neurophysiology, 132(9), 2062–2064.

Research in clinical populations 12 publications

1. L‑theanine relieves positive, activation, and anxiety symptoms in patients with schizophrenia and schizoaffective disorder: an 8‑week, randomized, double‑blind, placebo‑controlled, 2‑center study (2011) – Ritsner, M. S. et al. Journal of Clinical Psychiatry, 72(1), 34–42.
2. Effects of chronic L‑theanine administration in patients with major depressive disorder: an open‑label study (2017) – Hidese, S. et al. Acta Neuropsychiatrica, 29(2), 72–79.
3. L‑theanine in the adjunctive treatment of generalized anxiety disorder: A double‑blind, randomised, placebo‑controlled trial (2019) – Sarris, J. et al. Journal of Psychiatric Research, 110, 31–37.
4. The effects of L‑theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double‑blind, placebo‑controlled clinical trial (2011) – Lyon, M. R. et al. Alternative Medicine Review, 16(4), 348–354.
5. L‑theanine adjunct to sertraline for major depressive disorder: A randomized, double‑blind, placebo‑controlled clinical trial (2023) – Shamabadi, A. et al. Journal of Affective Disorders, 333, 38–43.
6. L‑Theanine adjunct to risperidone in the treatment of chronic schizophrenia inpatients: a randomized, double‑blind, placebo‑controlled clinical trial (2023) – Shamabadi, A. et al. Psychopharmacology, 240(12), 2631–2640.
7. L‑theanine combination therapy with fluvoxamine in moderate‑to‑severe obsessive‑compulsive disorder: A placebo‑controlled, double‑blind, randomized trial (2023) – Nematizadeh, M. et al. Psychiatry and Clinical Neurosciences, 77(9), 478–485.
8. Effects of L‑theanine‑caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof‑of‑concept neuroimaging RCT (2020) – Kahathuduwa, C. N. et al. Scientific Reports, 10(1), 13072.
9. Effect of L‑theanine on glutamatergic function in patients with schizophrenia (2015) – Ota, M. et al. Acta Neuropsychiatrica, 27(5), 291–296.
10. Add‑On Pregnenolone with L‑Theanine to Antipsychotic Therapy Relieves Negative and Anxiety Symptoms of Schizophrenia: An 8‑Week, Randomized, Double‑Blind, Placebo‑Controlled Trial (2018) – Kardashev, A. et al. Clinical Schizophrenia & Related Psychoses, 12(1), 31–41.
11. Serum levels of brain‑derived neurotrophic factor and cortisol to sulfate of dehydroepiandrosterone molar ratio associated with clinical response to L‑theanine as augmentation of antipsychotic therapy in schizophrenia and schizoaffective disorder patients (2011) – Miodownik, C. et al. Clinical Neuropharmacology, 34(4), 155–160.
12. A combination of green tea extract and L‑theanine improves memory and attention in subjects with mild cognitive impairment: a double‑blind placebo‑controlled study (2011) – Park, S. K. et al. Journal of Medicinal Food, 14(4), 334–343.

CP2305 — 10 Human Research Publications

Including 9 clinical trial reports and 1 meta‑analysis.

Stress research (5 clinical trials and 1 meta‑analysis) 6 publications

1. Effects of heat‑treated Lactobacillus gasseri CP2305 on brain oscillatory activity and mental stress in healthy adults: a double‑blind, randomized, crossover, placebo‑controlled trial (2026) – Tanihiro, R. et al. Frontiers in Nutrition, 13, 1796729.
2. Daily administration of paraprobiotic Lactobacillus gasseri CP2305 ameliorates chronic stress‑associated symptoms in Japanese medical students (2017) – Nishida, K. et al. Journal of Functional Foods, 36, 112–121.
3. Health Benefits of Lactobacillus gasseri CP2305 Tablets in Young Adults Exposed to Chronic Stress: A Randomized, Double‑Blind, Placebo‑Controlled Study (2019) – Nishida, K. et al. Nutrients, 11(8), 1859.
4. Daily intake of Lactobacillus gasseri CP2305 relieves fatigue and stress‑related symptoms in male university Ekiden runners: A double‑blind, randomized, and placebo‑controlled clinical trial (2019) – Sawada, D. et al. Journal of Functional Foods, 57, 465–476.
5. Para‑psychobiotic Lactobacillus gasseri CP2305 ameliorates stress‑related symptoms and sleep quality (2017) – Nishida, K. et al. Journal of Applied Microbiology, 123(6), 1561–1570.
6. Daily consumption of Lactobacillus gasseri CP2305 improves quality of sleep in adults – A systematic literature review and meta‑analysis (2023) – Chu, A. et al. Clinical Nutrition, 42(8), 1314–1321.

Gut health and other population‑specific research (clinical trials) 3 publications

1. Regulatory effect of paraprobiotic Lactobacillus gasseri CP2305 on gut environment and function (2016) – Sugawara, T. et al. Microbial Ecology in Health and Disease, 27, 30259.
2. Effects of Lactobacillus gasseri CP2305 on Mild Menopausal Symptoms in Middle‑Aged Women (2022) – Sawada, D. et al. Nutrients, 14(9), 1695.
3. The effects of administration of the Lactobacillus gasseri strain CP2305 on quality of life, clinical symptoms and changes in gene expression in patients with irritable bowel syndrome (2017) – Nobutani, K. et al. Journal of Applied Microbiology, 122(1), 212–224.

Safety research (clinical trial) 1 publication

1. Evaluation of the safety of high‑dose Lactobacillus gasseri CP2305 supplementation in healthy adults: A randomized, double‑blind, placebo‑controlled study (2026) – Fuchida, H. et al. Toxicology Reports, 16, 102222.

L. helveticus R0052 + B. longum R0175 — 9 Human Research Publications

Research on the combination of L. helveticus R0052 and B. longum R0175. Includes 7 randomized trial reports and 2 pilot studies.

Stress, anxiety and mood (randomized trials) 5 publications

1. Probiotic food supplement reduces stress‑induced gastrointestinal symptoms in volunteers: a double‑blind, placebo‑controlled, randomized trial (2008) – Diop, L. et al. Nutrition Research, 28(1), 1–5.
2. Assessment of psychotropic‑like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects (2011) – Messaoudi, M. et al. British Journal of Nutrition, 105(5), 755–764.
3. Beneficial psychological effects of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in healthy human volunteers (2011) – Messaoudi, M. et al. Gut Microbes, 2(4), 256–261.
4. Effects of a Psychobiotic Supplement on Serum Brain‑derived Neurotrophic Factor Levels in Depressive Patients: A Post Hoc Analysis of a Randomized Clinical Trial (2020) – Heidarzadeh‑Rad, N. et al. Journal of Neurogastroenterology and Motility, 26(4), 486–495.
5. Psychobiotic Effects on Anxiety Are Modulated by Lifestyle Behaviors: A Randomized Placebo‑Controlled Trial on Healthy Adults (2023) – Morales‑Torres, R. et al. Nutrients, 15(7), 1706.

Gut function, safety and other studies 4 publications

1. A Randomized Controlled Trial Evaluating the Effects of a Probiotic Containing Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 on Gastrointestinal Symptoms and Metabolomic Profiles in Female Dancers (2025) – Wiącek, J. et al. International Journal of Molecular Sciences, 26(12), 5823.
2. Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 Supplementation: An Exploratory, Randomized, Placebo‑Controlled Trial of Endocannabinoid and Inflammatory Responses in Female Dancers (2025) – Wiącek, J. et al. Microorganisms, 13(6).
3. Total Transit Time and Probiotic Persistence in Healthy Adults: A Pilot Study (2023) – Tremblay, A. et al. Journal of Neurogastroenterology and Motility, 29(2), 218–228.
4. The Efficacy, Safety, and Tolerability of Probiotics on Depression: Clinical Results From an Open‑Label Pilot Study (2021) – Wallace, C. J. K. et al. Frontiers in Psychiatry, 12, 618279.

About This List

These studies evaluated L‑theanine, heat‑treated L. gasseri CP2305 and the R0052 and R0175 probiotic strains individually—not the finished Arctic Composure formula. See The Evidence for a summary of key findings, or read more about how these ingredients are used in Arctic Composure.