Figure 1. L-theanine reduces heart rate variability during an acutely stressful task.
Figure 1. L-theanine reduces the state-trait anxiety index during an acutely stressful task.
Caffeine and L-theanine can act synergistically to improve alertness and attention. L-theanine can also potentially reverse some of the less favorable physiological effects of caffeine - including increased blood pressure, and reduced flow of oxygenated blood to the head. (Learn more)
Scheid, L., Ellinger, S., Alteheld, B., Herholz, H., Ellinger, J., Henn, T., . . . Stehle, P. (2012). Kinetics of L-theanine uptake and metabolism in healthy participants are comparable after ingestion of L-theanine via capsules and green tea. The Journal of nutrition, 142(12), 2091-2096.
Kakuda, T., Nozawa, A., Sugimoto, A., & Niino, H. (2002). Inhibition by theanine of binding of [3H]AMPA, [3H]kainate, and [3H]MDL 105,519 to glutamate receptors. Biosci Biotechnol Biochem, 66(12), 2683-2686.
Yokogoshi, H., Kato, Y., Sagesaka, Y. M., Takihara-Matsuura, T., Kakuda, T., & Takeuchi, N. (1995). Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats. Biosci Biotechnol Biochem, 59(4), 615-618.
Kakuda, T., Nozawa, A., Unno, T., Okamura, N., & Okai, O. (2000). Inhibiting effects of theanine on caffeine stimulation evaluated by EEG in the rat. Biosci Biotechnol Biochem, 64(2), 287-293. doi:10.1271/bbb.64.287
Unno, K., Tanida, N., Ishii, N., Yamamoto, H., Iguchi, K., Hoshino, M., . . . Yamada, H. (2013). Anti-stress effect of theanine on students during pharmacy practice: positive correlation among salivary alpha-amylase activity, trait anxiety and subjective stress. Pharmacol Biochem Behav, 111, 128-135. doi:10.1016/j.pbb.2013.09.004
Unno, K., Fujitani, K., Takamori, N., Takabayashi, F., Maeda, K., Miyazaki, H., . . . Hoshino, M. (2011). Theanine intake improves the shortened lifespan, cognitive dysfunction and behavioural depression that are induced by chronic psychosocial stress in mice. Free Radic Res, 45(8), 966-974. doi:10.3109/10715762.2011.566869
Yin, C., Gou, L., Liu, Y., Yin, X., Zhang, L., Jia, G., & Zhuang, X. (2011). Antidepressant-like effects of L-theanine in the forced swim and tail suspension tests in mice. Phytother Res, 25(11), 1636-1639. doi:10.1002/ptr.3456
Siamwala, J. H., Dias, P. M., Majumder, S., Joshi, M. K., Sinkar, V. P., Banerjee, G., & Chatterjee, S. (2013). L-theanine promotes nitric oxide production in endothelial cells through eNOS phosphorylation. J Nutr Biochem, 24(3), 595-605. doi:10.1016/j.jnutbio.2012.02.016
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 (Berl), 195(4), 569-577. doi:10.1007/s00213-007-0938-1
Dodd, F. L., Kennedy, D. O., Riby, L. M., & Haskell-Ramsay, C. F. (2015). 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. Psychopharmacology (Berl), 232(14), 2563-2576. doi:10.1007/s00213-015-3895-0
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