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Journals / Akademik Gıda / 2026 / Cilt: 17 Sayı: 3

Composition and Health Effect of Tea Plant (Camellia sinensis)

Çay Bitkisinin (Camellia sinensis) Bileşimi ve Sağlık Etkileri

Cemre Elmas0000-0003-1769-5155
Ceren Gezer0000-0002-5647-0103
Pages
417–428
Publication Date
2019-11-18
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AI Summary & Key Takeaways

AI Insight
⚡ TL;DR(Too Long; Didn't Read)

In this study, it is aimed to review the bioactive constituents of tea and their effect on human health.

📌 3 Key Takeaways

🎯
Objective & Hypothesis:Tea is one of the most widely consumed beverages worldwide.
📊
Key Findings & Data:The effect of tea on human health is often related to phytochemicals in its composition.
💡
Conclusion & Impact:In this study, it is aimed to review the bioactive constituents of tea and their effect on human health.
🔬Design:Review & Systematic Survey
📍Scope:Comprehensive Sample
⚙️Variables:Camellia sinensis · Çay · Flavonoid

Abstract

Tea is one of the most widely consumed beverages worldwide. The effect of tea on human health is often related to phytochemicals in its composition. During tea production, fermentation may produce variations by the amount and type of bioactive components present in the tea content. Catechins in the tea polyphenols show antioxidant activity. These components contribute to the prevention of diseases such as obesity, diabetes, cardiovascular diseases and cancer. It is also stated that these components may have protective effects against viral, bacterial and neurological diseases. In this study, it is aimed to review the bioactive constituents of tea and their effect on human health.

Özet

Dünya çapında yaygın olarak tüketilen içeceklerden olan çayın sağlık üzerine etkisi çoğunlukla bileşiminde bulunan fitokimyasallar ile ilişkilendirilmektedir. Çay üretim aşamasında fermantasyon işlemi, çay içeriğinde bulunan biyoaktif bileşenlerin çeşit ve miktarlarında değişiklikler oluşturmaktadır. Çay polifenollerinden kateşinlerin antioksidan aktivite ile obezite, diyabet, kardiyovasküler hastalıklar ve kanser gibi hastalıkların önlenmesine katkıda bulunduğu, aynı zamanda bu bileşenlerin antiviral, antibakteriyel ve nörolojik hastalıklara karşı koruyucu etkileri olduğu belirtilmektedir. Bu derlemede çayın bileşimi ve sağlık üzerine etkilerinin irdelenmesi hedeflenmiştir.

🔖

Cite This Article

Elmas, C., Gezer, C. (2019). Composition and Health Effect of Tea Plant (Camellia sinensis). Akademik Gıda, Cilt: 17 Sayı: 3, 417–428. https://doi.org/10.24323/akademik-gida.647733

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References (91)

  1. Damiani, E., Bacchetti, T., Padella, L., Tiano, L., Carloni, P. (2014). Antioxidant activity of different white teas: Comparison of hot and cold tea infusions. Journal of Food Composition and Analysis, 33(1), 59-66.
  2. Silva Pinto, M. (2013). Tea: A new perspective on health benefits. Food Research International, 53(2), 558-567.
  3. Chacko, S.M., Thambi, P.T., Kuttan, R., Nishigaki, I. (2010). Beneficial effects of green tea: a literature review. Chinese Medicine, 5(1), 13.
  4. Arab, H., Maroofian, A., Golestani, S., Sohrabi, K., Forouzanfar, A. (2011). Review of The therapeutic effects of Camellia sinensis (green tea) on oral and periodontal health. Journal of Medicinal Plants Research, 5(23), 5465-5469.
  5. Lambert, J.D. (2013). Does tea prevent cancer? Evidence from laboratory and human intervention studies. The American Journal of Clinical Nutrition, 98(6), 1667S-1675S.
  6. Aykaç, G., Uzun, M.B., Özçelikay, G. (2013). Tea In Every Aspect “Camellia sinensis”-Her Yönüyle Çay “Camellia sinensis”. Mersin Üniversitesi Tıp Fakültesi Lokman Hekim Tıp Tarihi ve Folklorik Tıp Dergisi, 4(1), 1.
  7. Alikılıç, D. (2016). Çay’ın Karadeniz Bölgesi İçin Önemi ve Tarihi Seyri. Journal of Black Sea Studies, 21, 269-280.
  8. Lin, Y.S., Tsai, Y.J., Tsay, J.S., Lin, J.K. (2003). Factors affecting the levels of tea polyphenols and caffeine in tea leaves. Journal of Agricultural and Food Chemistry, 51, 1864-1873.
  9. Kuo, K., Weng, M., Chiang, C., Tsaj, Y., Lin-Shiau, S., Lin, J. (2005). Comparative studies on the hypolipidemic and growth suppressive effects of oolong, black, pu-erh, and green tea leaves in rats. Journal of Agricultural and Food Chemistry, 53, 480-489.
  10. Vyas, D., Kumar, S. (2005). Tea (Camellia sinensis (L.) O. Kuntze) clone with lower period of winter dormancy exhibits lesser cellular damage in response to low temperature. Plant Physiology and Biochemistry, 43, 383-388.
  11. Perrier, A. (2004). Book of Tea. The new tea companion, Octopus Publishing Group Ltd., London.
  12. Heber, D., Zhang, Y., Yang, J., Ma, J.E., Henning, S. M., Li, Z. (2014). Green tea, black tea, and oolong tea polyphenols reduce visceral fat and inflammation in mice fed high-fat, high-sucrose obesogenic diets. The Journal of Nutrition, 144(9), 1385-1393.
  13. Tan, J., Engelhardt, U.H., Lin, Z., Kaiser, N., Maiwald, B. (2017). Flavonoids, phenolic acids, alkaloids and theanine in different types of authentic Chinese white tea samples. Journal of Food Composition and Analysis, 57, 8-15.
  14. Türk Gıda Kodeksi, Çay Tebliği, (Tebliğ No: 2015/30)
  15. Besler, H.T. (2008). Çay ve Sağlık İlişkisi. Sağlık Bakanlığı Yayını, Ankara.
  16. Belitz, H.D., Grosch, W., Schieberle, P. (2009). Food Chemistry. Springer-Verlag Berlin Heidelberg, Germany.
  17. McCance, Widdowson’s., (2002). The Composition of Foods. 6, RSH Publishing, Cambridge
  18. Gübür, S. (2015). Basit Karbonhidrat İçeriği Yüksek Diyetle Beslenen Sıçanlarda Yeşil Çayın Antioksidan Etkisinin İncelenmesi. Doktora Tezi, Başkent Üniversitesi.
  19. Liu, R.H. (2013). Health-promoting components of fruits and vegetables in the diet. Advances in Nutrition: An International Review Journal, 4(3), 384-392.
  20. Rains, T.M., Agarwal, S., Maki, K.C. (2011). Antiobesity effects of green tea catechins: a mechanistic review. The Journal of Nutritional Biochemistry, 22(1), 1-7.
  21. Bhagwat, S., Haytowitz, D.B., Holden, J.M. (2014). USDA Database for the flavanoid content of seleted foods, Release 3.1. US Department of Agriculture: Beltsville, MD, USA.
  22. Cooper, R., Morré, D.J., Morré, D.M. (2005). Medical benefits of green tea: part I. review of non-cancer health benefits. The Journal of Alternative and Complementary Medicine, 11(3), 521-528.
  23. Türk Kardiyoloji Derneği Ulusal Kalp Sağlığı Politikası (2006). 1-333p.
  24. De Koning Gans, J.M., Uiterwaal, C.S., Van der Schouw, Y.T., Boer, J.M., Grobbee, D.E., Verschuren, W.M., Beulens, J.W. (2010). Tea and coffee consumption and cardiovascular morbidity and mortality. Arteriosclerosis, Thrombosis, and Vascular Biology, 30(8), 1665-1671.
  25. Kuriyama, S., Shimazu, T., Ohmori, K., Kikuchi, N., Nakaya, N., Nishino, Y., Tsubono, Y., Tsuji, I. (2006). Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study. The Journal of the American Medical Association, 296, 1255-1265.
  26. Arts, I.C., Jacobs, D.R., Harnack, L.J., Gross, M., Folsom, A.R. (2001). Dietary catechins in relation to coronary heart disease death among postmenopausal women. Epidemiology, 12, 668-675.
  27. Geleijnse, J.M., Launer, L.J., Van der Kuip, D.A., Hofman, A., Witteman, J.C. (2002). Inverse association of tea and flavonoid intakes with incident myocardial infarction: the Rotterdam Study. The American Journal of Clinical Nutrition, 75, 880-886.
  28. Hirvonen, T., Pietinen, P., Virtanen, M., Ovaskainen, M.L., Hakkinen, S., Albanes, D., Virtamo, J. (2001). Intake of flavonols and flavones and risk of coronary heart disease in male smokers. Epidemiology, 12, 62-67.
  29. Peters, U., Poole, C., Arab, L. (2001). Does tea affect cardiovascular disease? A meta-analysis. American Journal of Epidemiology, 154, 495–503.
  30. Tengilioğlu, M.M., Büyüktuncer, Z. (2011). Çay ve sağlıkla ilişkisi. Beslenme ve Diyet Dergisi, 39(1-2), 59-65.
  31. Rogers, P.J., Smith, J.E., Heatherley, S.V., Pleydell-Pearce, C.W. (2008). Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together. Psychopharmacology, 195(4), 569.
  32. Wu, C.H., Lu, F.H., Chang, C.S., Chang, T.C., Wang, R.H., Chang, C.J. (2003). Relationship among habitual tea consumption, percent body fat, and body fat distribution. Obesity Research, 11, 1088-95.
  33. Phung, O.J., Baker, W.L., Atthews, L.J., Lanosa, M., Thorne, A., Coleman, C.I. (2010). Effect of gren tea catechins with or without caffeine on anthropometric measures: a systematic review and meta-analysis. The American Journal of Clinical Nutrition, 91, 73-81.
  34. Westerterp-Plantenga, M.S. (2010). Green tea catechins, caffeine and body-weight regulation. Physiology & Behavior, 100(1), 42-46.
  35. Shixian, Q., VanCrey, B., Shi, J., Kakuda, Y., Jiang, Y. (2006). Green tea extract thermogenesisinduced weight loss by epigallocatechin gallate inhibition of catechol-o-methyltransferase. Journal of Medicinal Food, 9, 451–8.
  36. Hodgson, J.M., Puddey, I.B., Burke, V., Croft, K.D. (2006). Is reversal of endothelial dysfunction by tea related to flavonoid metabolism? British Journal of Nutrition, 95, 14-17.
  37. Hursel, R., Westerterp-Plantenga, M.S. (2009). Green tea catechin plus caffeine supplementation to a high-protein diet has no additional effect on body-weight maintenance after weight loss. The American Journal of Clinical Nutrition, 89, 822-830.
  38. Cornelis, M.C., El-Sohemy, A., Campos, H. (2007). Genetic polymorphism of the adenosine A2A receptor is associated with habitual caffeine consumption. The American Journal of Clinical Nutrition, 86, 240-244.
  39. Klaus, S., Pültz, S., Thöne-Reineke, C., Wolfram, S. (2005). Epigallocatechin gallate attenuates diet-induced obesity in mice by decreasing energy absorption and increasing fat oxidation. International Journal of Obesity, 29, 615-623.
  40. Choo, J.J. (2003). Green tea reduces body fat accretion caused by high-fat diet in rats through beta-adrenoceptor activation of thermogenesis in brown adipose tissue. Journal of Nutritional Biochemistry, 14, 671-676.
  41. Hasegawa, N., Yamda, N., Mori, M. (2003). Powdered green tea has antilipogenic effect on Zucker rats fed a high-fat diet. Phytother Research, 17, 477-480.
  42. Ashida, H., Furuyashiki, T., Nagayasu, H., Bessho, H., Sakakibara, H., Hashimoto, T., Kanazawa, K. (2004). Anti-obesity actions of green tea: possible involvements in modulation of the glucose uptake system and suppression of the adipogenesis-related transcription factors. Biofactors 22: 135-140.
  43. Grove, K.A., Lambert, J.D. (2010). Laboratory, epidemiological, and human intervention studies show that tea (Camellia sinensis) may be useful in the prevention of obesity. The Journal of Nutrition, 140(3), 446-453.
  44. Van Dieren, S., Uiterwaal, C.S.P. M., Van der Schouw, Y.T., Boer, J.M.A., Spijkerman, A., Grobbee, D.E., Beulens, J.W.J. (2009). Coffee and tea consumption and risk of type 2 diabetes. Diabetologia, 52(12), 2561-2569.
  45. Greenberg, J.A., Axen, K.V., Schnoll, R., Boozer, C.N. (2005). Coffee, tea and diabetes: the role of weight loss and caffeine. International Journal of Obesity, 29(9), 1121.
  46. Sharangi, A.B. (2009). Medicinal and therapeutic potentialities of tea (Camellia sinensis L.)–A review. Food Research International, 42(5), 529-535.
  47. Odegaard, A.O., Pereira, M.A., Koh, W.P., Arakawa, K., Lee, H.P., Mimi, C.Y. (2008). Coffee, tea, and incident type 2 diabetes: the Singapore Chinese Health Study. The American Journal of Clinical Nutrition, 88(4), 979-985.
  48. Iso, H., Date, C., Wakai, K. Fukui, M., Tamakoshi, A. (2006). The relationship between green tea and total caffeine intake and risk for self-reported type 2 diabetes among Japanese adults. Annals of Internal Medicine, 144, 554-62.
  49. Hamer, M., Witte, D.R., Mosdøl, A., Marmot, M.G., Brunner, E.J. (2008). Prospective study of coffee and tea consumption in relation to risk of type 2 diabetes mellitus among men and women: the Whitehall II study. British Journal of Nutrition, 100(5), 1046-1053.
  50. Baysal, A., Aksoy, M., Besler, T., Bozkurt, N., Keçecioğlu, S., Pekcan, G., Mercanlıgil, S.M., Yıldız, E. (2011). Diyet El Kitabı. 6, Hatipoğlu Yayınevi, Ankara, 425p.
  51. Sies, H., Schewe, T., Heiss, C., Kelm, M. (2005). Cocoa polyphenols and inflammatory mediators. The American Journal of Clinical Nutrition, 81(1), 304-312. [52] Khalatbary, A.R., Ahmadvand, H. (2011). Anti-inflammatory effect of the epigallocatechin gallate following spinal cord trauma in rat. Iranian Biomedical Journal, 15, 31-37.
  52. Yu, N.H., Pei, H., Huang, Y.P., Li, Y.F. (2017). (-)-Epigallocatechin-3-gallate inhibits arsenic- induced inflammation and apoptosis through suppression of oxidative stress in mice. Cellular Physiology and Biochemistry, 41, 1788-1800.
  53. Çelik, F. (2006). Çay (Camellia sinensis); içeriği, sağlık üzerindeki koruyucu etkisi ve önerilen tüketimi. Turkiye Klinikleri Journal of Medical Sciences, 26(6), 642-648.
  54. Öğünç, A.V., Şehirli, A.Ö., Laçin, B.K., Ercan, F., Güçlü, H., Topçu, G. (2016). sıçanlarda deneysel mide ülseri modelinde yeşil çay ekstraktı ve peynir altı suyu proteinlerinin etkileri. Academic Food Journal/Akademik GIDA, 14(2), 111-122.
  55. Oak, M.H., El Bedoui, J., Schini-Kerth, V.B. (2005). Antiangiogenic properties of natural polyphenols from red wine and gren tea. The Journal of Nutritional Biochemistry, 16, 1-8.
  56. El Bedoui, J., Oak, M., Anglard, P., Schini-Kerth, V.B. (2005). Catechins prevent vascular smooth muscle cell invasion by inhibiting MT1-MMP activity and MMP-2 expression. Cardiovascular Research, 67, 317-25.
  57. Chowdhury, A., Sarkar, J., Chakraborti, T., Pramanik, P. K., Chakraborti, S. (2016). Protective role of epigallocatechin-3-gallate in health and disease: a perspective. Biomedicine & Pharmacotherapy, 78, 50-59.
  58. Jian, L., Xie, L.P., Lee, A.H., Binns, C.W. (2004). Protective effect of green tea against prostate cancer: A case-control study in southeast China. Internatioal Journal of Cancer, 108, 130-135.
  59. Doss, M.X., Potta, S.P., Hescheler, J., Sachinidis, A. (2005). Trapping of growth factors by catechins: A possible therapeutical target for prevention of proliferative diseases. The Journal of Nutritional Biochemistry, 16, 259-66.
  60. Wang, Y., Duan, H., Yang, H. (2015). A case-control study of stomach cancer in relation to Camellia sinensis in China. Surgical Oncology, 24(2), 67-70.
  61. Albrecht, D.S., Clubbs, E.A., Ferruzzi, M., Bomser, J.A. (2008). Epigallocatechin-3-gallate (EGCG) inhibits PC-3 prostate cancer cell proliferation via MEK-independent ERK1/2 activation. Chemico-Biological Interactions, 171(1), 89-95.
  62. Thangapazham, R.L., Passi, N., Maheshhwari, R.K. (2014). Green tea polyphenol and epigallocatechin gallate induce apoptosis and inhibit invasion in human breast cancer cells. Cancer Biology & Therapy, 6(12), 1938-1943.
  63. Onoda, C., Kuribayashi, K., Nirasawa, S., Tsuji, N., Tanaka, M., Kobayashi, D., Watanabe, N. (2011). (-)-Epigallocatechin-3-gallate induces apoptosis in gastric cancer cell lines by down-regulating survivin expression. International Journal of Oncology, 38(5), 1403-1408.
  64. Friedman, M. (2007). Overview of antibacterial, antitoxin, antiviral, and antifungal activities of tea flavonoids and teas. Molecular Nutrition & Food Research, 51(1), 116-134.
  65. Padmini, E., Valarmathi, A., Rani, M.U. (2010). Comparative analysis of chemical composition and antibacterial activities of Mentha spicata and Camellia sinensis. Asian Journal of Experimental Bioogical Sciences, 1(4), 772-781.
  66. Steinmann, J., Buer, J., Pietschmann, T., Steinmann, E. (2013). Anti‐infective properties of epigallocatechin‐3‐gallate (EGCG), a component of green tea. British Journal of Pharmacology, 168(5), 1059-1073.
  67. Reygaert, W., Jusufi, I. (2013). Green tea as an effective antimicrobial for urinary tract infections caused by Escherichia coli. Frontiers in Microbiology, 4, 1-4.
  68. Kumar, A., Kumar, A., Thakur, P., Patil, S., Payal, C., Kumar, A., Sharma, P. (2012). Antibacterial activity of green tea (Camellia sinensis) extracts against various bacteria isolated from environmental sources. Recent Research in Science and Technology, 4(1), 19-23.
  69. Chan, E., W., Soh, E.Y., Tie, P.P., Law, Y.P. (2011). Antioxidant and antibacterial properties of green, black, and herbal teas of Camellia sinensis. Pharmacognosy Research, 3(4), 266.
  70. Song, J.M., Lee, K.H., Seong, B.L. (2005). Antiviral effect of catechins in green tea on influenza virus. Antiviral Research, 68(2), 66-74.
  71. Trevisanato, S.I., Kim, Y.I. (2000). Tea and health. Nutrition Reviews, 58(1), 1-10.
  72. Hamilton-Miller, J.M. (2001). Anti-cariogenic effects of tea (Camellia sinensis). Journal of Medical Microbiology, 50, 299-302.
  73. Smullen, J., Koutsou, G.A., Foster, H.A., Zumbé, A., Storey, D.M. (2007). The antibacterial activity of plant extracts containing polyphenols agains Streptococcus mutans. Caries Research, 41, 342-349.
  74. Hassani, A.S., Amirmozafari, N., Ordouzadeh, N., Hamdi, K., Nazari, R., Ghaemi, A. (2008). Volatile components of Camellia sinensis inhibit growth and biofilm formation of oral Streptococci in vitro. Pakistan Journal of Biological Sciences, 11, 1336-41.
  75. Narotzki, B., Levy, Y., Aizenbud, D., Reznick, A.Z. (2013). Green tea and its major polyphenol EGCG increase the activity of oral peroxidases. In Respiratory Regulation-The Molecular Approach Springer, Dordrecht, 99-104p.
  76. Tehrani, M.H., Asghari, G., Hajiahmadi, M. (2011). Comparing Streptococcus mutans and Lactobacillus colony count changes following green tea mouth rinse or sodium fluoride mouth rinse use in children (Randomized double-blind controlled clinical trial). Dental Research Journal, 8(1), 158.
  77. Signoretto, C., Burlacchini, G., Bianchi, F., Cavalleri, G., Canepari, P. (2006). Differences in microbiological composition of saliva anddental plaque in subjects with different drinking habits. New Microbioliogica, 29, 293-302.
  78. Awadalla, H., Ragab, M., Bassuoni, M., Fayed, M., Abbas, M. (2011). A pilot study of the role of green tea use on oral health. International Journal of Dental Hygiene, 9, 110-116.
  79. Koyama. Y., Kuriyama, S., Aida, J., Sone, T., Nakaya, N., Ohmori-Matsuda, K., Hozawa, A., Tsuji, I. (2010). Association between green tea consumption and tooth loss: Cross-sectional results from the Ohsaki Cohort 2006 Study. Preventive Medicine, 50, 173-179.
  80. Demirel, G., Kumsar, A.K., Yılmaz, F.T. (2015). Kadınlarda osteoporozun önlenmesinde yeşil çayın yeri. Turkish Journal of Osteoporosis/Turk Osteoporoz Dergisi, 21(2), 84-86.
  81. Shen, C.L., Yeh, J.K., Cao, J.J., Chyu, M.C., Wang, J.S. (2011). Green tea and bone health: evidence from laboratory studies. Pharmacological Research, 64(2), 155-161.
  82. Shen, C.L., Chyu, M.C., Yeh, J.K., Zhang, Y., Pence, B.C., Felton, C.K., Wang, J.S. (2012). Effect of green tea and Tai Chi on bone health in postmenopausal osteopenic women: a 6-month randomized placebo-controlled trial. Osteoporosis International, 23(5), 1541-1552.
  83. Shen, C.L., Cao, J.J., Dagda, R.Y., Chanjaplammootil, S., Lu, C., Chyu, M.C., Yeh, J.K. (2012). Green tea polyphenols benefits body composition and improves bone quality in long-term high-fat diet–induced obese rats. Nutrition Research, 32(6), 448-457.
  84. Al-Othman, A., Al-Musharaf, S., Al-Daghri, N.M., Yakout, S., Alkharfy, K.M., Al-Saleh, Y., Kumar, S. (2012). Tea and coffee consumption in relation to vitamin D and calcium levels in Saudi adolescents. Nutrition Journal, 11(1), 56.
  85. Wang, G., Liu, L.H., Zhang, Z., Zhang, F., Li, S., Chen, Y., Zhao, H. (2014). Oolong tea drinking could help prevent bone loss in postmenopausal Han Chinese women. Cell Biochemistry and Biophysics, 70(2), 1289-1293.
  86. Mähler, A., Mandel, S., Lorenz, M., Ruegg, U., Wanker, E.E., Boschmann, M., Paul, F. (2013). Epigallocatechin-3-gallate: a useful, effective and safe clinical approach for targeted prevention and individualised treatment of neurological diseases? European Association for Predictive, Preventive, Personalised Medicine Journal, 4(1), 5.
  87. Weinreb, O., Mandel, S., Amit, T., Youdim, M.B.H. (2004). Neurological mechanisms of green tea polyphenols in Alzheimer’s and Parkinson’s diseases. The Journal of Nutritioanl Biochemistry, 15, 506-516.
  88. Pan, T.H., Jankovic, J., Le, W.D. (2003). Potential therapeutic properties of green tea polyphenols in Parkinson’s disease. Drugs Aging, 20, 711-721.
  89. Ng, T.P., Feng, L., Niti, M., Kua, E. H., Yap, K.B. (2008). Tea consumption and cognitive impairment and decline in older Chinese adults. American Journal of Clinical Nutrition, 88, 224-231.
  90. Niu, K., Hozawa, A., Kuriyama, S., Ebihara, S., Guo, H., Nakaya, N., Ohmori-Matsuda, K., Takahashi, H., Masamune, Y., Asada, M. (2009). Green tea consumption is associated with depressive symptoms in the elderly. American Journal of Clinical Nutrition, 90(6), 1615-1622.
  91. Kimura, K., Ozeki, M., Juneja, L.R., Ohira, H. (2007). L-Theanine reduces psychological and physiological stress responses. Biological Psychology, 74, 39-45.