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Acute effects of tea consumption on attention and mood


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Tea has historically been associated with mood and performance benefits, such as relaxation and concentration. This review summarizes the research on the acute effects of tea, and its ingredients theanine and caffeine, on attention and mood. Consistent with abundant research on the benefits of caffeine, the performance benefits of tea were identified in a number of studies, with particularly consistent evidence for improved attention. Tea consumption also consistently improved self-reported alertness and arousal, whereas effects on pleasure or relaxation were less consistent. In addition to the research on caffeine in real-life performance, 2 recent studies have provided a broader perspective on tea's effects on psychological function in that they showed beneficial effects in related areas such as work performance and creativity. These studies showed the validity of laboratory findings by supporting the idea that tea consumption has acute benefits on both mood and performance in real-life situations.
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Acute effects of tea consumption on attention and mood
Suzanne J Eino
¨ther and Vanessa E Martens
Tea has historically been associated with mood and performance
benefits, such as relaxation and concentration. This review summa-
rizes the research on the acute effects of tea, and its ingredients the-
anine and caffeine, on attention and mood. Consistent with abundant
research on the benefits of caffeine, the performance benefits of tea
were identified in a number of studies, with particularly consistent
evidence for improved attention. Tea consumption also consistently
improved self-reported alertness and arousal, whereas effects on
pleasure or relaxation were less consistent. In addition to the research
on caffeine in real-life performance, 2 recent studies have provided
a broader perspective on tea’s effects on psychological function in
that they showed beneficial effects in related areas such as work
performance and creativity. These studies showed the validity of
laboratory findings by supporting the idea that tea consumption
has acute benefits on both mood and performance in real-life
situations. Am J Clin Nutr 2013;98(suppl):1700S–8S.
Whereas consumers have historically associated tea with mental
benefits, these alleged benefits were largely anecdotal until rela-
tively recently. In the past 15 y, the effects of tea consumption on
mental performance, especially attention, and mood have been
investigated in a number of studies. Notably, the studies reviewed
here mainly pertain to relatively acute effects of tea and tea in-
gredients, which occur immediately after consumption or during
the course of a day, in healthy adult populations. The timing of the
occurrence of these benefits contrasts with the research on neu-
roprotective effects of tea that used longitudinal designs, which
have suggested long-term benefits of tea consumption in elderly or
impaired populations (1). Whereas the literature on tea’s acute
psychological benefits focuses on outcome measures such as at-
tention and mood, the primary focus of the literature on tea’s
chronic health benefits lies in prevention of cardiovascular disease
(2–4), diabetes (5, 6), depression (7, 8), and neurodegenerative
diseases such as dementia (1, 9). The underlying mechanisms for
acute and chronic benefits are likely to be different; the acute
effects have been ascribed to caffeine and theanine, whereas the
chronic effects have been linked to other components in tea, such
as flavonoids. Based on the knowledge currently available, the
different outcome measures and different underlying mechanisms
appear to hinder linking tea’s acute benefits to tea’s chronic
benefits. In this article, we mainly focus on the acute benefits of
tea on attention and mood.
In September 2012, relevant studies were identified through
searches of the PubMed (
and Scopus ( electronic databases by
using the entry terms “tea,” “caffeine, or “theanine” in combi-
nation with “attention,” “concentration,” “alertness,” “cognition,”
“cognitive function,” or “mood.” We limited our search to journal
articles written in English. To be included, studies were required
to investigate the effects of tea, caffeine, and/or theanine; report
data on at least one acute behavioral measure of attention or
mood; include at least one (sub)sample of healthy adults; include
a control condition; and have been published in a peer-reviewed
journal. Relevance was assessed on the basis of the titles and
abstracts. Finally, relevant articles that appeared until April 2013
in the electronic databases of PubMed and Scopus were included.
According to the American Psychological Association, at-
tention is “a state of focused awareness on a subset of the
available perceptual information.” Attention allows the brain to
effectively deal with the vast amount of input that is continu-
ously received through its sensory (eg, vision, hearing) and
cognitive (eg, memory) processes and to focus on what is rel-
evant. As such, attention is an important prerequisite for many
cognitive processes, including memory and reasoning. Attention
can be measured objectively as performance on attention tests,
usually in terms of speed of response and number of correct
responses, or subjectively as self-reported alertness, usually by
means of a visual analog rating scale (VAS)
From Unilever Research and Development, Vlaardingen, Netherlands.
Presented at the conference “Fifth International Scientific Symposium on
Tea and Human Health,” held at the US Department of Agriculture, Wash-
ington, DC, 19 September 2012. The conference was organized by Jeffrey
Blumberg, Tufts University, Boston, MA, and a Steering Committee includ-
ing representatives from each of the symposium cosponsors: the American
Cancer Society, the American College of Nutrition, the American Institute for
Cancer Research, the American Medical Women’s Association, the American
Society for Nutrition, and the Linus Pauling Institute. The symposium was
underwritten by the Tea Council of the USA. Its contents are solely the re-
sponsibility of the authors and do not necessarily represent the official views of
the Tea Council of the USA or the cosponsoring organizations.
SJE received travel support from the Tea Council of the USA for speaking
at the Fifth International Scientific Symposium on Tea and Human Health.
Address correspondence to SJ Eino
¨ther, Sensation Perception & Behaviour
Group, Unilever Research and Development, Vlaardingen, PO Box 114, 3130
AC Vlaardingen, Netherlands. E-mail:
Abbreviations used: CFFT, Critical Flicker Fusion Threshold; EGCG,
epigallocatechin-3-gallate; VAS, visual analog scale.
First published online October 30, 2013; doi: 10.3945/ajcn.113.058248.
1700S Am J Clin Nutr 2013;98(suppl):1700S–8S. Printed in USA. Ó2013 American Society for Nutrition
by guest on January 19, 2017ajcn.nutrition.orgDownloaded from
Acute effects of tea ingredients on attention
Tea contains a large number of bioactive compounds, yet its
attention benefits have generally been attributed to 2 of its com-
ponents: caffeine and theanine (11). Typically, a cup of tea contains
35–61 mg caffeine and 4.5–22.5 mg theanine. Other ingredients
in tea, such as the green tea polyphenol epigallocatechin-3-
gallate (EGCG), have been ascribed certain neuroprotective
effects (12), but acute effects on performance measures have
not been found (13).
There is a large body of evidence that caffeine is highly
bioavailable because it is rapidly and almost completely absorbed
(14) and readily distributed throughout all tissues of the body (15)
including the brain (16). Peak plasma concentrations are reached
at w30 min postconsumption, and half-lives for elimination
range between 2.5 and 10 h, dependent on the food matrix,
genetic factors, and smoking status (14, 17). Caffeine is exten-
sively metabolized in the liver into .25 derivatives, whereas
considerably less than 5% of the ingested dose is excreted un-
changed in the urine (14).
Caffeine is known to affect neurotransmission in general by
antagonizing (ie, competing with) adenosine receptors. When
adenosine binds to its receptors in the brain, primarily A1 and
A2a receptors, neural activity slows down. However, when
caffeine binds instead to these receptors it causes a general increase
in neurotransmission (18–20). As such, caffeine attenuates the
inhibitory effects of adenosine in the brain. As an adenosine
antagonist, caffeine also affects the dopaminergic system (21),
which is involved in arousal and higher-order attentional pro-
cesses (22). In addition, caffeine has secondary effects on the
release of specific neurotransmitters, including noradrenaline,
acetylcholine, serotonin, glutamate, and g-aminobutyric acid,
which have been hypothesized to be involved in caffeine’s effect
on arousal (23).
Caffeine is present in a range of beverages (eg, tea, coffee, soft
drinks, energy drinks) and in some foods (eg, chocolate) and is
the most consumed psychoactive ingredient worldwide (24). Its
attention effects have been studied extensively (25, 26). Across
a large variety of tests and doses, these studies indicate that even
in low doses such as 50 mg (ie, approximately the equivalent of
a cup of tea) caffeine improves performance on attention tasks
and subjective alertness. Whereas effects on simple attention
tasks have been well established, recent studies have also in-
dicated beneficial effects of caffeine on more complex, multi-
faceted attention tasks (27–29).
Theanine is an amino acid that is virtually unique to tea (apart
from the fungus Bay bolete). Theanine has been shown to be
highly bioavailable, reaching its maximum concentration in
plasma at w45 min postadministration (30). It is metabolized
into glutamic acid and ethylamine, and a minor fraction is ex-
creted into urine (30–33). On administration of theanine, con-
centrations of some other amino acids (eg, tryptophan, tyrosine)
were reduced in the brain in rats (34). Some of these amino acids
are precursors of neurotransmitters that are important for cog-
nitive performance (eg, tryptophan is converted into serotonin,
and tyrosine is converted into dopamine), which are both in-
volved in higher-order complex attention processes in humans
(serotonin: references 35 and 36; dopamine: reference 37).
Hence, it has been suggested that theanine may attenuate neu-
rotransmitter levels by interfering with the availability of their
precursors and thus affect cognition. In addition, theanine can
bind to receptors and transporters involved in glutamate and
g-aminobutyric acid neurotransmission (37, 38), neurotrans-
mitters that are also involved in attention performance (39, 40).
For theanine, the psychoactive properties appear to be more
complex than caffeine. During rest, theanine increases awave
brain activity, which has been associated with relaxation (41, 42).
During attention task performance, theanine increased back-
ground (resting) aactivity, yet decreased aactivity when pre-
paring to attend to the task stimuli (43, 44), which has been related
to better performance (45). Behavioral effects of theanine were
largely absent. However, these studies were designed to measure
brain activity rather than behavioral effects.
Because caffeine and theanine are always consumed together
when consuming tea, studying the effects of these ingredients in
combination is more relevant than studying either ingredient in
isolation. Few studies have investigated this combination, and
most of them used an increased amount of theanine, compared
with the amount typically present in tea. This combination im-
proved speed and accuracy on a range of tasks from the Cognitive
Drug Research test battery (46), improved accuracy on an
attention-switching test (47–49), improved accuracy on a cued
attention test (50), and improved accuracy on a sustained attention
test (51).
Acute effects of tea on attention
The evidence on tea ingredients indicates that tea can provide
cognitive benefits, in particular in the domain of attention. Four
studies to date have specifically assessed the effects of black tea
on attention performance. Details of these studies are shown in
Table 1. Hindmarch et al (52) compared the effects of coffee,
water, and tea with and without 100 mg caffeine on 2 tasks that
are frequently used to measure attention effects in pharma-
ceutical trials, the Critical Flicker Fusion Threshold (CFFT)
and Choice Reaction Time tasks, and self-reported alertness.
Overall, caffeinated beverages improved performance and self-
reported alertness compared with decaffeinated beverages.
Interestingly, performance on the CFFT improved more after
caffeinated tea than after caffeinated water, suggesting that the
attention benefit cannot be wholly attributed to caffeine, and
that other tea components also contributed to the benefit.
Furthermore, whereas performance naturally declined over
time, this decline was attenuated by beverage type, in that tea
was associated with a smaller decrease (ie, better performance)
than water. Thus, this study provided tentative evidence for
a beneficial effect of tea on a performance measure related to
attention. In a follow-up study, main effects of caffeine (37.5
and 75 mg, respectively) on both tasks were replicated (53).
Moreover, CFFT performance improved after consumption of tea
with 75 mg caffeine, compared with coffee with the same amount
of caffeine. In sum, these findings suggest that tea effects—at
least on simple attention tasks—are not merely a result of caffeine
and that on some outcomes tea might “outperform” coffee. No-
tably, both studies were of an open-label design and thus did
not control for expectations and taste differences between the
Two recent studies used a double-blind, placebo-controlled
crossover design and more complex attention tasks to further
investigate these effects (54). In the first study, 26 healthy
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participants consumed 2 cups of black tea and a placebo tea
(colored and flavored water) on separate test sessions. After each
cup, participants completed 2 complex tasks of attention (at-
tention-switching task and intersensory attention task) and a self-
rating of alertness, calmness, and contentment. Results indicated
that accuracy on the attention-switching task was better after tea
than after placebo. Moreover, participants also provided more
accurate responses on 2 of the 4 subtasks of the intersensory
attention task and also responded faster on 1 of these 2 tasks.
Finally, participants felt more alert and less calm after tea
consumption. In a replication of this study, participants consumed
3 cups of tea that consisted of a slightly weaker tea blend (54),
followed by the same tasks as the previous study after each cup.
Again, accuracy on the attention-switching task improved after
black tea compared with placebo, and participants also reported
feeling more alert. Tea did not significantly affect performance
on the intersensory attention task. The authors speculated that
this difference between the studies could be a result of the dif-
ference in the strength of the tea blend and of the potentially dose-
dependent build-up of the active ingredients in plasma.
From the totality of research on tea summarized above and in
Table 1, it can be concluded that consumption of black tea may
improve attention and self-reported alertness. These conclusions
are further supported by studies on caffeine and on theanine and
caffeine in combination.
The influence of food and beverage consumption on mood has
been (and still is) widely researched. Mood refers to a state of
mind ranging from increased happiness, contentment, relaxation,
alertness and energy, and relief of depression and anxiety to
Acute effects of tea consumption on attention
First author, year (reference) Sample Design Results
Hindmarch, 1998 (52) 19 Healthy volunteers; 10 F, 9 M;
mean age = 29.2 y
Randomized CO design, 5 conditions:
–black tea, 100 mg caffeine
–black tea, decaffeinated
–coffee, 100 mg caffeine
–water, 100 mg caffeine
–water, noncaffeinated
CFFT: overall, tea improved
performance vs water (P=
0.034); acutely caffeinated
beverage improved CFFT
level vs noncaffeinated
beverages (P= 0.024)
CRT: no significant effects
Hindmarch, 2000 (53) 30 Healthy volunteers; 15 F, 15 M;
mean age = 27.3 y
Randomized CO design, 5 conditions:
–black tea, 37.5 mg caffeine
–black tea, 75 mg caffeine
–coffee, 75 mg caffeine
–coffee, 150 mg caffeine
–hot water, noncaffeinated
CFFT: caffeinated beverages
resulted in superior
performance overall (P=
0.0376) and immediately
after drink 1 (P= 0.0425) vs
water; also, tea improved
performance 30–90 min
postconsumption (P,0.01)
after drink 1 vs coffee
CRT: caffeinated beverages
resulted in improved
recognition reaction times
after drink 2 vs water (P=
0.0486); also, coffee
improved recognition
reaction time (P= 0.0484)
after drink 2 vs tea
De Bruin, 2011 (54)
Study 1 26 Healthy volunteers; 20 F, 16 M;
mean 6SD age = 30.7 611.2 y
Randomized PC CO design, 2 conditions:
–black tea
–placebo tea
Attention-switching task:
improved accuracy after tea
Intersensory attention task:
improved accuracy on
multisensory auditory and
visual tasks after tea (P,
0.001 and P,0.030,
respectively) and faster
responses to the visual task
(P= 0.043)
Study 2 32 Healthy volunteers; 15 F, 17 M;
mean 6SD age = 30.3 610.1 y
Randomized PC CO design, 2 conditions:
–black tea
–placebo tea
Attention-switching task:
improved accuracy after tea
(P= 0.007)
Intersensory attention task: no
significant effects
Line analog rating scale and Bond-Lader self-reported alertness scores are reported in Table 2. CFFT, Critical Flicker Fusion Threshold (task); CO,
crossover; CRT, Choice Reaction Time (task); PC, placebo-controlled.
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feelings of guilt and failure (55). The consumption of tea, both
black and green, has been associated with relaxation and re-
freshment (56, 57) and feelings of satisfaction (58). These pu-
tative benefits may be the result of the interaction of a number of
elements, including the hot temperature at which tea is con-
sumed, its sensory properties (eg, smell, color, mouth-feel), and
its active ingredients, which exert effects at different times during
and after tea consumption. In the studies summarized below, the
effects of tea or tea ingredients on mood have been investigated
by using various validated scales with self-reports (eg, Bond-
Lader VAS, Profile of Mood States, University of Wales Institute
of Technology Mood Adjective Checklist). These include facets
of mood related to arousal and relaxation, as well as aspects
related to the pleasantness of mood. In addition, particular changes
in mood related to arousal and alertness can also be determined
with physiologic measures, for example, blood pressure and skin
conductance (59).
Acute effects of tea ingredients on mood
Caffeine is well known for its effects on feelings of arousal,
energy, and alertness (60, 61), even at doses as low as 50 mg,
which is comparable to the amount of caffeine in a cup of tea. In
addition, a number of studies also found improved hedonic tone
(62, 63), happiness and calmness (64), and contentment (65) after
caffeine consumption. The number of studies on the effects of
theanine in relation to mood is limited. Three studies found
benefits in relation to stress: 200 mg theanine reduced self-
reported anxiety in anticipation of a stressful event (66) or after
a mental task (67) and reduced physiologic indexes of stress such
as heart rate and salivary immunoglobulin during engagement in
a stressful task (68). Another study found that 250 mg caffeine
increased self-rated alertness, jitteriness, and blood pressure,
with 200 mg theanine antagonizing caffeine’s effect on blood
pressure but not its effects on alertness or jitteriness (69). Al-
though psychological health benefits (including lower risk of
cognitive decline) have been ascribed to tea flavonoids in
cross-sectional studies (67), there is limited evidence for acute
effects of these ingredients in healthy adults. Notably, the
catechin EGCG has recently been associated with increased
calmness and reduced stress in one study that used a 300-mg
dose (12) but not in another study in which a lower dose of
135 mg was used (13).
Acute effects of tea on mood
A range of studies have assessed the effect of tea on mood (for
an overview see Table 2). However, most of these studies fo-
cused on alertness or arousal, which is closely related to atten-
tion. Findings consistently show an increase in self-reported
alertness or arousal after consuming black tea (and other caf-
feinated beverages) compared with consumption of noncaffeinated
beverages. Five studies found reduced ratings of sedation on a line
analog rating scale, reflecting higher alertness, immediately after
tea consumption (70) or 30 and 60 min after consumption of
caffeinated beverages including tea (52, 53, 71) compared with
noncaffeinated beverages. In addition, 3 studies found increased
ratings of energetic arousal after consumption of caffeinated
beverages, including tea, compared with noncaffeinated bev-
erages (71, 72). Two studies reported increased alertness rat-
ings after black tea consumption compared with placebo on
the Bond-Lader VAS (54). In one recent study (SJL Eino
M Baas, M Rowson, T Giesbrecht, unpublished data, 2012),
no effect of tea on arousal (using an affect grid) when com-
pared with water was found; in contrast to most of the pre-
viously mentioned studies, mood was assessed immediately
after consumption. Findings from physiologic measures, such
as skin conductance and blood pressure, which are collected
under controlled laboratory settings, further support that black
tea can stimulate the autonomous nervous system in a manner
associated with increased arousal (70, 71).
With regard to valence of mood or pleasure, findings with tea
are less consistent. Quinlan et al (72) found improved hedonic
tone after drinking any beverage (ie, black tea, coffee, hot water)
at 30 and 60 min after consumption compared with a condition
with no drink at all. In a follow-up study, the researchers again
found improved hedonic tone but after all caffeinated beverages,
including black tea, compared with noncaffeinated beverages
(71). However, these findings were not replicated in a second
study in the same report (54, 71), which found no significant
effects of black tea consumption on contentment. All of these
studies focused on the effects of the active ingredients, which are
expected to be absorbed and distributed to the brain relatively
soon after consumption. An alternative hypothesis not driven by
active ingredients, however, might be that subjective mood is
affected around and/or immediately after consumption because
of the sensory “tea experience” itself, including (the combina-
tion of) the activity of preparing the tea and its smell, taste,
mouth-feel, and visual appearance, which is a hypothesis that
was not tested in any of the studies described above. Finally, in
a recent study (SJL Eino
unpublished data, 2012), tea consumption (as well as a positive
control) positively affected pleasantness of mood immediately
after consumption compared with water.
To date, no studies have assessed the acute effects of tea on
self-reported relaxation. However, 2 studies have attempted to
relate tea consumption to stress relief. Steptoe et al (73) in-
vestigated the effects of daily tea consumption during 6 wk in
healthy men. Whereas tea consumption did not affect blood
pressure or heart rate, it did reduce platelet activation before
and after stress, reduced cortisol concentrations, and increased
subjective relaxation at the end of the recovery period, reflecting
a positive effect of tea on recovery from stress. In addition, cross-
sectional data on healthy Japanese adults showed that a high
consumption of green tea (.5 cups daily) was related to lower
psychological distress, even after adjustment for possible con-
founders (74).
Although caffeine is known to affect various aspects of mood,
in particular alertness, effects of other ingredients such as the-
anine or EGCG on mood are largely unknown. The effects of tea
on self-reported alertness and arousal have been well researched
and have consistently shown a positive effect, which is consistent
with the findings for caffeine. In contrast, only a few studies
addressed the effect of tea on pleasure/hedonic tone and/or re-
laxation, and their results were variable.
Laboratory interventions using validated measures indicate
that tea consumption exerts acute positive effects on attention
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Acute effects of tea consumption on self-reported mood
First author, year
(reference) Sample Design Results
Aspen, 1998 (70) 16 Healthy volunteers;
8 F, 8 M; age .18 y
Randomized CO design, 7 conditions:
–black tea, swallowed or rinsed
–caffeinated water, swallowed or rinsed
–water, swallowed or rinsed (no caffeine)
–no drink, control
LARS: ,10 min; more alert, energetic,
attentive, clearheaded, refreshed, and
less tired (P,0.05) after tea vs
caffeinated water, regardless of rinse
or swallow; relaxed, calm, tense, sad,
happy unaffected
30 min; more alert, energetic,
attentive, clearheaded, refreshed, and
less tired (P,0.01) after caffeinated
beverages if swallowed; more calm,
relaxed, and less tense after tea vs
caffeinated water and after caffeinated
beverages vs water (P,0.05); more
happy, less sad after caffeinated
beverages (P,0.01)
Quinlan, 1997 (72) 16 Healthy volunteers;
8 F (mean 6SD age =
34.4 611.8 y); 8 M
(mean 6SD age =
36.9 66.3 y)
Randomized CO design, 10 conditions:
–black tea, decaffeinated or 100 mg caffeine
–black tea with milk, decaffeinated or 100 mg caffeine
–coffee, black tea, decaffeinated or 100 mg caffeine
–coffee with milk, decaffeinated or 100 mg caffeine
–hot water, decaffeinated or 100 mg caffeine
–no drink
UMACL: Hedonic tone improved by hot
beverages vs no drink at 30 min (P=
0.0024) and 60 min (P= 0.02)
postconsumption; tense or energetic
arousal rating unaffected
Energetic arousal, hedonic tone
improved by caffeinated vs
noncaffeinated beverages at 30 min
(energetic arousal: P= 0.0001;
hedonic tone: P= 0.0025) and 60 min
(energetic arousal: P= 0.000; hedonic
tone: P= 0.015) postconsumption;
tense arousal ratings unaffected
STAI: anxiety improved by caffeinated
vs noncaffeinated beverages at 60 min
postconsumption (P= 0.05)
Hindmarch, 1998 (52) 19 Healthy volunteers;
10 F, 9 M; mean
age = 29.2 y
Randomized CO design, 6 conditions:
–black tea, decaffeinated or 100 mg caffeine
–coffee, decaffeinated or 100 mg caffeine
–hot water, noncaffeinated or 100 mg caffeine
LARS: Daylong effects: reduced sedation
after caffeinated vs noncaffeinated
beverages (P= 0.033)
Acute effects: interactions between
caffeine amount and time (P= 0.025);
reduced sedation by caffeinated vs
noncaffeinated beverages, most
prominent for coffee
STAI: no significant effects
Hindmarch, 2000 (53) 30 Healthy volunteers;
15 F, 15 M; mean age =
27.3 y
Randomized CO design, 5 conditions:
–black tea, 37.5 mg or 75 mg caffeine
–coffee, 75 mg or 150 mg caffeine
–hot water, noncaffeinated
LARS: No daylong effects but acute
effects at drink 1 (P= 0.0110): reduced
sedation after caffeinated beverages vs
water (P= 0.0049)
Quinlan, 2000 (71)
Study 1 17 Healthy volunteers;
9 F, 8 M; mean age =
35 y
Randomized CO design, 6 conditions:
–black tea 37.5 mg or 75 mg caffeine
–coffee, 75 mg or 150 mg caffeine
–hot water, noncaffeinated
–no drink
UMACL: energetic arousal (P= 0.05),
hedonic tone (P= 0.007) increased by
caffeinated vs noncaffeinated
beverages; tense arousal rating
LARS: sedation reduced by caffeinated
vs noncaffeinated beverages (P=
0.03) and by coffee vs tea (P= 0.04);
dose-dependent: 150 mg resulted in
greater increase than 75 mg (P= 0.03)
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and aspects of mood. Although such findings have good internal
reliability, the generalizability to the complex cognitive de-
mands of everyday life has been questioned. Few studies in-
vestigated whether benefits could be extended to everyday
Effects of tea ingredients in real life
The performance benefits of caffeine have been identified in
real-life tasks. For example, caffeine is recognized by the US
military as an “alertness-enhancing compound” (75) and has
been shown to improve vigilance during military combat (76–
78). Beneficial effects of caffeine consumption on simulated
and/or actual driving are commonly found under extreme cir-
cumstances, such as after sleep deprivation (79–82) or during
nighttime driving (83). Moreover, 2 studies have shown ben-
efits in nonfatigued subjects during daytime on outcomes
corresponding to safer and more stable driving. The con-
sumption of caffeine (3 mg/kg) improved steering accuracy
during a 1-h simulated drive (84). Furthermore, 80 mg caffeine
consumed after 2 h of monotonous simulated driving improved
lane keeping and speed maintenance during a 2-h follow-up
drive (85). In contrast, Heatherley et al (86) found no signifi-
cant effects of caffeine (1.2 mg/kg) on steering variability, but
this study may have been underpowered. Furthermore, a review
of 13 studies of shift work performance showed that caffeine
can reduce errors and improve cognitive performance in shift
workers, compared with no intervention (87). Finally, other
studies have indicated that caffeine (100 mg) improved self-
reported concentration while attending a university lecture
when compared with placebo (88) and improved passing ac-
curacy during a simulated soccer game (6 mg/kg) (89). No
studies to date have assessed the effects of theanine or other tea
ingredients on real-life tasks.
Effects of tea in real life
Recent meta-analyses have confirmed that positive mood
states lead to improved creative problem solving compared with
neutral mood states (90, 91). Because tea has been shown to affect
mood, it was hypothesized that consumption of tea and tea-based
beverages would enhance creativity via positive affect. Isen et al
(92) reported that tasting a cup of commercially available or
branded iced tea led to more creative problem solving on an
adapted Remote Associate Test when compared with tasting
bottled water and compared with no intervention. This finding
was confirmed recently (SJL Eino
¨ther, M Baas, M Rowson,
T Giesbrecht, unpublished data, 2012) through a study in which
hot black tea was found to positively affect pleasantness of mood
immediately after consumption, as well as creative problem
solving. Specifically, both tea and a validated positive affect
induction (a procedure for recalling happy personal memories)
were found to increase feelings of pleasantness compared with
water immediately after consumption. Furthermore, there was
an indication that both positive affect–inducing conditions im-
proved creative problem solving compared with water, in that
both tended to yield faster insights on difficult problems.
In addition, 2 cross-sectional studies have assessed associa-
tions between consumption of tea (and other beverages) and
performance and mood by using a naturalistic design. Steptoe
et al (93) tested participants from 2 high-stress-occupation groups
who completed daily reports of beverage consumption and
mood for 8 wk and found a relation between tea consumption and
mood. In contrast, Bryan et al (94) asked professional and ac-
ademic staff to complete reports of beverage consumption and
mood and work performance during 10 working days. Their
results indicated that participants who consumed more tea felt
less tired and reported that they performed well at work more
often than participants who drank less tea—but only if it
was consumed without milk and/or sugar. In addition, higher
TABLE 2 (Continued )
First author, year
(reference) Sample Design Results
Study 2 15 Healthy volunteers;
8 F, 7 M; mean
age = 33.9 y
Randomized CO design, 6 conditions:
–black tea, decaffeinated or 25, 50, 100, or 200 mg
–hot water, noncaffeinated
UMACL: caffeine increased energetic
arousal (P= 0.006); dose-dependent
(P= 0.046): lowest and highest dose
produced largest increase; tense
arousal, hedonic tone unaffected
LARS: caffeine (P= 0.0003) reduced
sedation; dose-dependent (P=
0.0003): all doses except for 50 mg
produced an effect
De Bruin, 2011 (54)
Study 1 26 Healthy volunteers;
20 F, 16 M; mean 6
SD age = 30.7 6
11.2 y
Randomized PC CO design, 2 conditions:
–black tea
–placebo tea
Bond-Lader VAS: more alert (P,0.001)
and less calm (P= 0.008) after tea
vs placebo; contentment rating
Study 2 32 Healthy volunteers;
15 F, 17 M; mean 6
SD age = 30.3 6
10.1 y
Randomized PC CO design, 2 conditions:
–black tea
–placebo tea
Bond-Lader VAS: more alert after tea
(P= 0.021) and tendency toward
greater feelings of contentment (P=
0.085) after tea vs placebo; calmness
rating unaffected
CO, crossover; LARS, line analog rating scale; PC, placebo-controlled; STAI, State Trait Anxiety Inventory; UMACL, University of Wales Institute of
Technology Mood Adjectives Checklist; VAS, visual analog scale.
by guest on January 19, 2017ajcn.nutrition.orgDownloaded from
consumption of noncaffeinated beverages was associated with
feeling more relaxed. Coffee did not have a stronger relation
than other beverages with any of the variables assessed.
Tea is one of the most consumed beverages in the world, and its
many putative benefits appear to be well known and appreciated by
consumers. We have summarized the acute psychological benefits
of tea on attention and mood in an effort to link some of these
anecdotal beliefs to the existing science. The tea ingredients
caffeine and theanine, alone or in combination, have been linked to
attention, with the available research showing that consumption of
black tea improves attention on validated complex tasks as well as
self-reported alertness. Mood benefits of tea and tea ingredients,
other than improved alertness, have been less extensively re-
searched until now, and these findings are less consistent. The
psychological benefits of tea and tea ingredients have been ex-
tended to some real-life areas including driving, creativity, and
work performance.
Research on the benefits of tea is promising for attention and
alertness, although questions remain regarding the scope and
magnitude of impact as well as the sensitivity of different in-
dividuals. Whereas the bioavailability of both caffeine and the-
anine has been established (14–17, 30–33), as well as the
(suggested) mechanisms of action in the brain (18–23, 34–40), the
extent to which they actually cross the blood-brain barrier in
humans and how much this is associated with (individual)
changes in subsequent performance and mood measures are as yet
unknown. It would be interesting to conduct a study in humans
measuring cerebrospinal fluid concentrations of caffeine and
theanine after acute ingestion of tea and to correlate the con-
centrations with the acute effects on attention, mood, and real-life
performance. Other cognitive processes, such as memory or
specific aspects of memory (eg, working memory), that encom-
pass a large component of the attention domain, have not yet been
investigated in relation to the acute effects of tea consumption.
Indeed, very few studies have been conducted outside of the
laboratory, and it would be highly relevant to better understand
the effects of tea consumption on other daily activities that re-
quire attention—for example, driving and cooking. Similarly, few
studies have objectively assessed the acute effects of tea on
pleasant feelings and relaxation, attributes that are often associ-
ated with each other by tea consumers. Investigating mood states
during and after consumption of tea with validated measures will
further build our understanding of the potential benefit of tea in
this aspect of health and well-being.
Research on the benefits of caffeine on driving and other types of
real-life performance is consistent with results from laboratory
studies with regard to improved alertness, reduced fatigue, and
sustained performance benefits. Recent research provides tentative
support for the hypothesis that benefits from tea can be found in
related areas such as creative problem solving. Similarly, a cross-
sectional study has shown that tea consumption improves self-
reported work performance and fatigue. These results also warrant
replication and further research. Nevertheless, the available evi-
dence on the benefits of tea and tea ingredients on mood and
performance in real-life settings does support the validity of findings
from earlier laboratory-controlled studies on attention and mood.
The authors’ responsibilities were as follows—SJE: conducted literature
research; and SJE and VEM: wrote the manuscript. The authors are em-
ployees of Unilever, which markets tea and tea-based beverages.
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... Previous research indicated that teas exhibit plenty pro-health properties including reducing obesity and blood glucose levels (Jigisha et al., 2012;Shi and Schlegel, 2012;Hosoda et al., 2003;He et al., 2009;Panagiotakos et al., 2009;Oba et al., 2010), concentration and immunity (Hammer, 2007), lowers total cholesterol levels (Sinija and Mishra, 2008), preventing several types of cancer (Huang et al., 2014;Michalak-Majewska, 2011;Seow et al., 2020;Sinija and Mishra, 2008;Jigisha et al., 2012;Shi and Schlegel, 2012), brain strokes (Arab et al., 2013), furthermore make possible more efficient heart muscle (Stańczyk, 2010;Jigisha et al., 2012;Shi and Schlegel, 2012), expansion of coronary and brain vessels and of bronchi, increasing body temperature (Stańczyk, 2010), diarrhea prevention (Doustfatemeh et al., 2016), contraction (Einöther and Martens, 2013), anti-inflammation (Sanliera et al., 2018;Sinija and Mishra, 2008;Shi and Schlegel, 2012), bactericidal and bacteriostatic effects, alleviation of burning and itching (Stańczyk, 2010;Jigisha et al., 2012), protects against solar radiation (Michalak-Majewska, 2011), antiviral and anticaries effects (Michalak-Majewska, 2011;Sanliera et al., 2018;Sinija and Mishra 2008;Jigisha et al., 2012), protection of the nervous system (Steptoe et al., 2007;Unno et al., 2017), slowing down the aging process (Stańczyk, 2010;Sanliera et al., 2018;Jigisha et al., 2012), lessening the symptoms of depression. ...
... According to the relevant literature and the available meta-analyses on health properties of Chinese teas, tea exhibits the following health properties: cognitive benefits, especially related to concentration (eg when switching attention), reduction of anxiety in anticipation of a stressful event, as well as physiological stress indicators and increased alertness (Einöther and Martens, 2013), prevention of lithiasis (green tea, Nasrul and Sehgal, 2020), reducing the risk of lung cancer (black teas, Seow et al., 2019) and head and neck cancer (Huang et al., 2014), positive association between tea consumption and telomere length (Chan et al., 2010), lessening the symptoms of depression (Shen et al., 2019;Niu et al., 2009;O'Neill Rothenberg et al., 2019), reducing the risk of osteoporosis (Sun et al., 2017) and bone health (Li et al., 2018), effect on treatment of chronic periodontitis (Kazem, 2018), reducing the risk of stroke (Arab et al., 2013), anti-mutagenic, anti-viral, antioxidant, anti-inflammatory properties (Sanliera et al., 2018). ...
... Epidemiological studies have suggested that regular consumption of tea, one of the most consumed beverages in the world, may improve cardiovascular health and affective function. 9,10 In fact, recent studies have confirmed that the consumption of black tea is an effective approach to improve cardiovascular function. 11,12 Furthermore, daily consumption of tea seems to reduce the risk for heart disease and ischemic stroke. ...
... 13 Tea consumption has also been linked to benefits related to attention, alertness, mood and creativity. 9 Although taking a break for a hot drink is a typical behavior among office-based workers, there is no study examining the effect of this behavior on cerebrovascular and affective function in a research setting. Therefore, this exploratory study evaluated the effects of light, short physical activity breaks with tea consumption at regular intervals during prolonged sitting in healthy, young office workers. ...
Full-text available
Background: Prolonged sitting, typical of desk work, decreases cerebral blood flow (CBF), mood and affect. Conversely, short physical activity breaks from sitting may prevent these detrimental effects and provide cardiometabolic benefits. Objective: We evaluated the effect of interrupting prolonged sitting with short breaks of light physical activity combined with tea consumption on CBF, cerebral autoregulation (CA), mood, and affect in desk workers. Methods: Nineteen healthy desk workers (ten male, 27±10 years) performed desk work in a laboratory for six hours on two separate intervention days: tea breaks (TEA-BREAK: short walk combined with ingestion of one cup of tea every hour) and sedentary (SED: ingestion of one cup of water every hour, while seated). Before and after desk work, we assessed mean arterial pressure (MAP), middle cerebral artery blood velocity (MCAv) and CA. Questionnaires were used to assess mood (Bond & Lader, PANAS) and affect (Affect grid) before and after the intervention. Data are expressed as mean ± standard deviation. Two-way ANOVA with repeated measurements followed by Sidak post hoc test was used for data analysis. Paired Student’s t-test was also used to compare changes (∆) between trials. Statistical significance was at p<0.05. Results: Desk work increased MAP (4.6±4.6 ∆ mmHg; P<0.05), and decreased MCAv (-5.2±7.0 ∆ cm/s; P<0.05), with no difference between interventions in these parameters. TEA-BREAKS, but not SED, decreased gain (-0.08±0.12 ∆ cm.s-1. mmHg.-1) and increased phase (5.26±8.84 ∆ radians) at very low frequency (P<0.05), but not at low frequency. Small changes in positive affect were found after the six hours of desk work (-5.5±7.3 ∆ scale; P<0.05), with no differences between interventions. Conclusion: Changes in MCAv and positive affect induced by prolonged desk work could not be prevented by TEA- BREAKS. However, TEA-BREAKS improved CA, suggesting a higher efficiency in maintaining MCAv in response to blood pressure fluctuations.
... Accumulating evidence (2)(3)(4) shows that the consumption of tea (including green, oolong, and black varieties) is associated with several beneficial outcomes for brain health (such as lower levels of depression). It was not until recent years, however, the effect of tea consumption on mood and mental performance has been increasingly investigated (5). For example, Schimidt et al. (6) found that eight weeks of green tea supplementation before the ischemia-reperfusion event showed a neuroprotective effect in male rats. ...
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Background Previous studies show that the consumption of tea is associated with several beneficial outcomes for brain health, but there is little data among the elderly in China. Objective The objective was to explore the longitudinal relationship between tea consumption and the risk of cognitive decline. Methods The current data was obtained from the China Longitudinal Aging Study (CLAS), and a total of 3,246 residents aged 60 years and above were recruited in this study. Some of them ( N = 111) underwent a standard T1-weighted magnetic resonance imaging (MRI), from which the volumes of the corpus callosum (CC) and hippocampus were calculated, and detailed tea consumption information was obtained through a standardized questionnaire at baseline. The cognitive diagnosis of each participant was made by attending psychiatrists at baseline and follow-up. Their overall cognitive function was assessed by the Montreal Cognitive Assessment (MoCA), while their associative learning ability was assessed by an associative learning test (ALT). Finally, 1,545 elderly with normal cognitive function completed the baseline and follow-up assessment and were included in the final study. Results After controlling gender, education, smoking, take exercise and hobbies, we found that the elderly with tea consumption habits had a lower incidence rate of cognitive decline ( p = 0.002, OR = 0.604, 95%CI:0.437~0.836) and tea consumption was negatively correlated with the change scores of MoCA (r = −0.056, p = 0.029). What's more, the CC_posterior volume of tea drinkers was significantly smaller than that of non-tea drinkers, while the baseline ALT score of tea drinkers was significantly higher than that of non-tea drinkers. The results of correlation analysis showed that the CC_posterior volume was significantly correlated with ALT change score (r = −0.319, p = 0.010). Conclusions The habit of tea consumption is associated with less incidence of cognitive impairment among the Chinese elderly, and it may prevent a decline in memory and associative learning by affecting the volume of the posterior corpus callosum.
... In Asian cultures where tea is largely consumed, it is traditionally considered a cognitive enhancer. Acute effects of tea consumption on mood and cognitive performance have been reported in some studies and have been linked to antioxidants contained in tea, such as epigallocatechin-3-gallate (EGCG), L-theanine, and caffeine [205]. In addition, it has been suggested that the neuroprotective actions of tea consumption may be mediated by inhibition of acetylcholinesterase and regulation of stress hormones [206]. ...
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Multiple factors combined are currently recognized as contributors to cognitive decline. The main independent risk factor for cognitive impairment and dementia is advanced age followed by other determinants such as genetic, socioeconomic, and environmental factors, including nutrition and physical activity. In the next decades, a rise in dementia cases is expected due largely to the aging of the world population. There are no hitherto effective pharmaceutical therapies to treat age-associated cognitive impairment and dementia, which underscores the crucial role of prevention. A relationship among diet, physical activity, and other lifestyle factors with cognitive function has been intensively studied with mounting evidence supporting the role of these determinants in the development of cognitive decline and dementia, which is a chief cause of disability globally. Several dietary patterns, foods, and nutrients have been investigated in this regard, with some encouraging and other disappointing results. This review presents the current evidence for the effects of dietary patterns, dietary components, some supplements, physical activity, sleep patterns, and social engagement on the prevention or delay of the onset of age-related cognitive decline and dementia.
... It is worth noting that the researchers observed that the 300 mg dose per day of EGCG in the participants increased calmness and reduced stress (Desmet & Schifferstein, 2008). Based on a doseresponse analysis of 2,107 cases of depression in 10,600 participants, Einöther and Martens found that the higher intake of tea, the lower risk of depression (Einöther & Martens, 2013). Dose-response analysis identified a positive association between tea drinking and antidepression effects. ...
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Tea polyphenols (TP) are one of the most functional and bioactive substances in tea. The interactions between TP and intestinal microbiota suggest that probiotics intervention is a useful method to ameliorate neurological diseases. Now, numerous researches have suggested that TP plays a significant role in modulating intestinal bacteria, especially in the area of sustaining a stable state of intestinal microbial function and abundance. Furthermore, homeostatic intestinal bacteria can enhance the immunity of the host. The close reciprocity between intestinal microbiota and the central nervous system provides a new chance for TP to modulate neural-related diseases depending on intestinal microbiota. Therefore, based on the bidirectional relationship between the brain and the intestines, this review provides a new clue to solve insomnia symptoms and related neurological diseases that will enable us to better study the bidirectional effects of TP and intestinal microbiota on the improvement of host health. Practical applications This review provides a new clue to solve insomnia symptoms and related neurological diseases that will enable us to better study bidirectional effects of TP and intestinal microbiota on the improvement of host health.
... For example, caffeine improves performance in simple and complex attention tasks, and affects alertness and executive control networks (Einöther and Giesbrecht 2013). Meanwhile, tea consumption improves psychological function such as that observed related to work performance and creativity (Einöther and Martens 2013). Moreover, the effects of milk are also gathering attention. ...
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Lactononadecapeptide (LNDP; NIPPLTQTPVVVPPFLQPE) is a memory-improving peptide. The current study aimed to determine the effects of a single dose of tablets containing LNDP on cognitive function in healthy Japanese men aged 30-59 years. A randomized, double-blind, cross-over, placebo-controlled trial was conducted in participants randomly assigned to receive LNDP or placebo tablets. The Uchida–Kraepelin test was used to induce cognitive load in participants as a model of work load. Cognitive function was evaluated using the Japanese version of the CNS Vital Signs. Composite memory and verbal memory were significantly higher following consumption of LNDP than placebo tablets. Carryover effects were observed in attention and concentration domains so that period 1 data was analyzed. LNDP consumption led to higher processing speed, executive function, and cognitive flexibility than placebo. Thus, supplementation with a single dose of LNDP tablets may improve cognitive functions including memory, attention, concentration, and information processing in daily life.
Tea is a widespread functional plant resource. Phytochemicals such as tea polyphenols (TP) can interact with the intestinal flora and participate in regulating the expression and rhythm of biological clock genes. Circadian rhythm controls a variety of behaviors and physiological processes, and circadian misalignment has been found to be closely related to multiple metabolic diseases. Interestingly, the gut microbiota also has diurnal fluctuations, which can be affected by diet composition and feeding rhythm, and play a role in maintaining the host’s circadian rhythm. The two-way relationship between the host’s circadian rhythm and intestinal microbiota confirms the possibility that prebiotics or probiotic can be used to adjust the intestinal environment and microbiome composition to improve the host health. This article reviews the relationship between the host’s circadian rhythm and microbiota and its influence on metabolic diseases. The beneficial effects of the interaction between TP and gut microbiota on diseases related to rhythm disorders are emphasized to improve the theories of disease prevention and treatment.
Tea consumption has been extensively shown to be closely related to physical health and cognitive abilities. However, there are no definite conclusions on the relationship between tea consumption and convergent thinking. Convergent thinking requires top-down cognitive processing, which focuses on searching for an appropriate idea based on well-defined criteria. It is a necessary part of the creative process and is inextricably linked to divergent thinking that requires people to search for many different ideas with less defined criteria within a wider search span. It has been found that tea consumption is beneficial to divergent thinking in creativity. Given that convergent thinking is related to divergent thinking, we hypothesized that drinking tea may also promote convergent thinking. This research was to investigate the enhancing effects of tea on convergent thinking and test its possible mediating mechanism (i.e., the role of positive emotions) and marginal conditions (e.g., the moderating roles of intelligence and tea preference). In Experiment 1, participants completed the Remote Associates Test (RAT) which requires the solver to create a meaningful link (word association) that mediates three seemingly unrelated cues (e.g., Same–Tennis–Head is mediated by Match) after drinking tea or water. The results showed that the type of drinks and tea consumption habits had a significant interaction effect on RAT scores. The participants who drank tea (v.s. water) performed best in the RAT. A “split half effect” was found. That is, participants' performance in different groups was significantly different in the second half of the RAT, suggesting that drinking tea leads to persistent problem-solving convergent thinking. Experiment 2 aimed to replicate the findings in Experiment 1 using a different convergent thinking task, namely, riddle tasks, where participants needed to solve riddles with different levels of difficulty. The results revealed that performance in the tea group on the difficult tasks was significantly higher than that in the water group; after controlling for knowledge level and intelligence, the differences in the performance in the medium- and high-difficulty riddle tasks between the two groups were significant. Although no experiments found a mediating effect of positive emotions, Experiment 2 showed that the participants in the tea group were happier and more interested in the task than those in the water group. To conclude, the positive effects of tea drinking on convergent thinking was demonstrated, and the moderating effects of knowledge level, intelligence, and tea drinking habits were elaborated. The results have important practical significance for those who are engaged in creative work or those who are prone to fatigue.
Negative emotions and sleep disorders are common health-related concerns faced by many people who live under some sort of pressure in modern society. In the long run, these issues can decline the immunity of a person, which in turn is closely related to the inflammatory signaling pathway that affects the brain. Clinical evidence suggests that the intestinal flora can regulate the host’s sleep and emotional status through the brain intestinal axis. As a dietary factor, tea polyphenols (TP) play a role in regulating mood and sleep. On the one hand, the intestinal flora can promote the metabolism and absorption of TP in the body to thereby improve their bioavailability. On the other hand, TP can modify the abundance of intestinal flora, improve the composition of beneficial flora and inhibit the growth of harmful bacteria. Considering that the epidemiological causes of anxiety, depression and sleep disorders involve the interaction of environmental stress and genetic predisposition in various physiological systems, treatment options that combine the intestinal microbiota and TP may prove superior to the classical pharmacological treatments because intestinal microbiota promotes the production of a variety of bioactive metabolites from dietary polyphenols that can simultaneously regulate the moods and sleep to improve the immunity. In this review, we discussed the relationship among TP, intestinal flora, emotion and sleep, as well as their interactions that promote the effective regulation of emotion and sleep, to ultimately improve the body’s immunity.
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Results of two studies indicated that tasting a familiar product designed to be refreshing (iced tea), without knowledge of the brand, induced positive affect, as did the gift-of-candy (not consumed) induction, used in many previous studies. As compared to controls, these participants showed more positive affect as reflected by 5 implicit measures and 2~explicit ratings of the refreshingness and pleasingness of the product. They performed significantly better on items from the Remote Associates Test (a test of creativity), generated more unusual and more pleasant first associates to a randomly selected letter of the alphabet, and to neutral words (the implicit measures). Results also indicated that similar affect did not arise when participants tasted a less liked, unfamiliar, brand of iced tea, without knowledge of the brand. However, when the brand name (a known brand) of that tea was presented with the less liked product sample, people who tasted that same tea showed positive affect responses on the implicit measures of affect and also explicitly rated the tea as more refreshing and pleasing than the unbranded version of the same tea.
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Key points: Catechins and other compounds, for example L-theanine, in tea have neuroprotective effects. Neuroprotective effects of tea compounds are due to multiple mechanisms. The main mechanisms include the anti-oxidant and anti-inflammatory properties of tea extracts and their effects on the modification of Alzheimer’s disease and its pathology. Many other mechanisms could be involved in the neuroprotective effects of tea. Population-based studies suggest that tea consumption is associated with a lower risk of cognitive impairment and cognitive decline. There is a linear relationship between tea consumption and cognitive performance. The cognitive benefits of tea consumption are not limited to the particular type of tea. Drinking tea could be a simple way to prevent cognitive decline, but more research is needed.
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Background/Objectives Ingestion of the non-proteinic amino acid l-theanine (γ-glutamylethylamide) has been shown to influence oscillatory brain activity in the alpha band (8–14 Hz) in humans during resting electroencephalographic (EEG) recordings and also during cognitive task performance. We have previously shown that ingestion of a 250-mg dose of l-theanine significantly reduced tonic (background) alpha power during a demanding intersensory (auditory-visual) attentional cueing task. Further, cue-related phasic changes in alpha power, indexing the shorter-term anticipatory biasing of attention between modalities, were stronger on l-theanine compared to placebo. This form of cue-contingent phasic alpha activity is also known to index attentional biasing within visual space. Specifically, when a relevant location is pre-cued, anticipatory alpha power increases contralateral to the location to be ignored. Here we investigate whether the effects of l-theanine on tonic and phasic alpha activity, found previously during intersensory attentional deployment, occur also during a visuospatial task. Subjects/Methods 168-channel EEG data were recorded from thirteen neurologically normal individuals while engaged in a highly demanding visuo-spatial attention task. Participants underwent testing on two separate days, ingesting either a 250-mg colorless and tasteless solution of l-theanine mixed with water, or a water-based solution placebo on each day in counterbalanced order. We compared the alpha-band activity when subjects ingested l-Theanine vs. Placebo. Results We found a significant reduction in tonic alpha for the l-theanine treatment compared to placebo, which was accompanied by a shift in scalp topography, indicative of treatment-related changes in the neural generators of oscillatory alpha activity. However, l-theanine did not measurably affect cue-related anticipatory alpha effects. Conclusions This pattern of results implies that l-theanine plays a more general role in attentional processing, facilitating longer-lasting processes responsible for sustaining attention across the timeframe of a difficult task, rather than affecting specific moment-to-moment phasic deployment processes.
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Background: The intake of food and drink can influence brain functions, which in turn may have effects on mental state and performance. Therefore, in principle claims to improve mood or specific aspects of cognitive performance by the consumption of functional foods are possible and indeed are currently found on the market. Aim: The paper reviews existing methodologies, which may be used to substantiate and validate such claims of desirable effects of foods on mental state and performance. Results: Mood, arousal, activation, vigilance, attention, sleep, motivation, effort, perception, memory and intelligence have been identified as relevant aspects of mental state and performance. The basic scientific concepts within this field as well as the methodologies to measure these concepts have been reviewed and described. Conclusions: From this review it is concluded that, in principle, the phenomena in these fields are no different to those in other fields of life science. The scientific methods and protocols described in this report can positively demonstrate the effects of foods on mental state and performance in a scientifically valid way. A claim on mental state and performance like other claims must be based on scientific evidence. This report confirms that methodologies do exist to generate sound scientific evidence in this area. Therefore, claims on the enhancement of specific mental functions can and should be substantiated and validated using the methodologies described in this review.
In an investigation of the mechanisms of the neuroprotective effects of theanine (gamma-glutamylethylamide) in brain ischemia, inhibition by theanine of the binding of [H-3](RS)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), [H-3]kainate, and [H-3](E)-3-(2-phenyl-2-carboxyethenyl)-4,6-dichloro-1-H-indole-2- carboxylic acid (MDL 105,519) to glutamate receptors was studied in terms of its possible inhibiting effects on the three receptor subtypes (AMPA, kainate, and NMDA glycine), with rat cortical neurons. Theanine bound the three receptors, but its IC50 of theanine was 80- to 30,000-fold less than that of L-glutamic acid.
The purpose of this study was to determine if there were age or gender specific effects of caffeine, as measured by cognitive tasks and mood assessments known to be sensitive to caffeine. The subjects were healthy, non-smoking volunteers between the ages of 18 and 30 (6 male and 6 female), and over the age of 60 (6 male and 6 female). Only low and moderate consumers of caffeine (daily intake < 400 mg) were enrolled in the double-blind, placebo controlled, crossover design. The order of caffeine dosing (placebo, 64, 128, and 256 mg) was counterbalanced by use of a complex Latin Square sequence of administration. Analysis of the data from all measures indicated that the effects of caffeine were no different in either males or females, or in the young or elderly volunteers. A significant dose-dependent improvement in performance of all subjects was observed in a modified version of the Wilkinson Auditory Vigilance Test. Additionally, significant dose-dependent improvements in mood state were observed in all ...