Bryan J. Psychological effects of dietary components of tea: Caffeine and L-theanine. Nutrition Rev, 2007

School of Psychology, University of South Australia, Adelaide, 5001, South Australia, Australia.
Nutrition Reviews (Impact Factor: 6.08). 03/2008; 66(2):82-90. DOI: 10.1111/j.1753-4887.2007.00011.x
Source: PubMed


This review summarizes the literature on the association between two dietary components of tea, caffeine and L-theanine, and the psychological outcomes of consumption; it also identifies areas for future research. The studies reviewed suggest that caffeinated tea, when ingested at regular intervals, may maintain alertness, focused attention, and accuracy and may modulate the more acute effects of higher doses of caffeine. These findings concur with the neurochemical effects of L-theanine on the brain. L-theanine may interact with caffeine to enhance performance in terms of attention switching and the ability to ignore distraction; this is likely to be reflective of higher-level cognitive activity and may be sensitive to the detrimental effects of overstimulation. Further research should investigate the interactive effects of caffeine, L-theanine, and task complexity, utilize a range of ecologically valid psychological outcomes, and assess the neuroprotective effects of L-theanine using epidemiological or longer-term intervention studies among individuals at risk of neurodegenerative disease.

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    • "In addition, a recent study demonstrated that l-theanine, a unique amino acid particularly enriched in green tea, promoted the survival of C. elegans in the presence of paraquat [92]. l-theanine has been reported to provide broad health benefits, such as antitumor, AD prevention, and blood pressure reduction [93] [94] [95] [96]. "
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    ABSTRACT: Aging is a complex and inevitable biological process that is associated with numerous chronically debilitating health effects. Development of effective interventions for promoting healthy aging is an active but challenging area of research. Mechanistic studies in various model organisms, noticeably two invertebrates, Caenorhabditis elegans and Drosophila melanogaster , have identified many genes and pathways as well as dietary interventions that modulate lifespan and healthspan. These studies have shed light on some of the mechanisms involved in aging processes and provide valuable guidance for developing efficacious aging interventions. Nutraceuticals made from various plants contain a significant amount of phytochemicals with diverse biological activities. Phytochemicals can modulate many signaling pathways that exert numerous health benefits, such as reducing cancer incidence and inflammation, and promoting healthy aging. In this paper, we outline the current progress in aging intervention studies using nutraceuticals from an evolutionary perspective in invertebrate models.
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    • "l-Theanine is an amino acid particularly contained in green tea. The compound has previously been shown to exert positive effects on mental state and may prevent an Alzheimer’s disease-like phenotype in murine models of this disease [3, 4]. Moreover, it appears to exert desirable effects on body mass [5] as well as blood pressure [6]. "
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    ABSTRACT: Compounds that delay aging in model organisms may be of significant interest to anti-aging medicine, since these substances potentially provide pharmaceutical approaches to promote healthy lifespan in humans. We here aimed to test whether pharmaceutical concentrations of L: -theanine, a putative anti-cancer, anti-obesity, blood pressure-lowering, and neuroprotective compound contained in green tea (Camellia sinensis), are capable of extending lifespan in a nematodal model organism for aging processes, the roundworm Caenorhabditis elegans. Adult C. elegans roundworms were maintained on agar plates, were fed E. coli strain OP50 bacteria, and L: -theanine was applied to agar to test (1) whether it may increase survival upon paraquat exposure and (2) whether it may promote longevity by quantifying survival in the presence and absence of the compound. L: -theanine increases survival of C. elegans in the presence of paraquat at a concentration of 1 micromolar. L: -theanine extends C. elegans lifespan when applied at concentrations of 100 nM, as well as 1 and 10 micromolar. In the model organism C. elegans, L: -theanine is capable of promoting paraquat resistance and longevity suggesting that this compound may as well promote healthy lifespan in mammals and possibly humans.
    Preview · Article · Mar 2012 · European Journal of Nutrition
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    • "Caffeine is well known to improve arousal and alertness (e.g. Bryan, 2008; Hewlett and Smith, 2007; see Brice and Smith, 2001 for a review), and the effects of caffeine on EEG measures have been studied in the context of a varied array of cognitive and attentional paradigms. Clear effects on cognitive performance and associated brain physiology are a near ubiquitous finding in the ERP literature. "
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    ABSTRACT: Caffeine and L-theanine, both naturally occurring in tea, affect the ability to make rapid phasic deployments of attention to locations in space as reflected in behavioural performance and alpha-band oscillatory brain activity (8-14 Hz). However, surprisingly little is known about how these compounds affect an aspect of attention that has been more popularly associated with tea, namely vigilant attention: the ability to maintain focus on monotonous tasks over protracted time-periods. Twenty-seven participants performed the Sustained Attention to Response Task (SART) over a two-hour session on each of four days, on which they were administered caffeine (50 mg), theanine (100 mg), the combination, or placebo in a double-blind, randomized, cross-over fashion. Concurrently, we recorded oscillatory brain activity through high-density electroencephalography (EEG). We asked whether either compound alone, or both in combination, would affect performance of the task in terms of reduced error rates over time, and whether changes in alpha-band activity would show a relationship to such changes in performance. When treated with placebo, participants showed a rise in error rates, a pattern that is commonly observed with increasing time-on-task, whereas after caffeine and theanine ingestion, error rates were significantly reduced. The combined treatment did not confer any additional benefits over either compound alone, suggesting that the individual compounds may confer maximal benefits at the dosages employed. Alpha-band oscillatory activity was significantly reduced on ingestion of caffeine, particularly in the first hour. This effect was not changed by addition of theanine in the combined treatment. Theanine alone did not affect alpha-band activity.
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