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with
alpha frequency band (8-13Hz) of the electroencephalogram
across parietal and occipital areas of the brain relative to placebo.
The alpha brain waves in the resting human volunteers were
generated within 40 minutes after the oral administration of Ltheanine (50–200 mg), signifying a state of relaxation without
drowsiness, according to the study authors3.
I
L-Theanine with Suntheanine contains 100% Suntheanine, a patented pure form of the amino acid L-theanine produced in Japan
from green tea leaves. This award-winning brand of theanine has
been the subject of numerous safety studies and human clinical
trials. One of green tea’s natural health-promoting compounds, Ltheanine (γ-glutamylethylamide) is synthesized in the roots of tea
plants and transported to the leaves, comprising about 2% of the
total dry weight of green tea leaves. It is the ingredient that is
responsible for both the taste and the relaxing effects of green tea.
Research shows that supplemental L-theanine crosses the bloodbrain barrier within 30 minutes of intake and thus is able to exert its
effects directly on the brain1.
A study performed at the Brain and Cognition Laboratory at Oxford University investigated whether a lower dose of Suntheanine®
L-theanine (50 mg) dissolved in tea would also affect alpha brain
wave activity. The Suntheanine® group consisted of 16 participants
who received 50 mg of Suntheanine dissolved in a tea infusion,
presumably containing caffeine. The control group consisted of 19
participants who received 100 mL cool water. EEG readings were
taken 45 minutes after ingestion and subsequently every 15 minutes (45, 60,75, 90, 105 minutes). Participants were resting with
their eyes closed during EEG recording. There was a greater
increase in alpha activity across time in the Suntheanine®
supplemented group relative to placebo (p<0.05) indicating that
this lower dose of L-theanine may also have a significant
effect on the feeling of relaxation1.
May enhance cognitive performance and promote
attention to detail*
Studies have been performed in which L-theanine was administered to rats daily for four months to assess its effect on memory and learning ability. Several tests were employed to determine
whether L-theanine could enhance memory and learning, including
BENEFITS
Promotes a relaxed state without drowsiness*
L-theanine with Suntheanine is best known for its unique ability to
promote relaxation without causing drowsiness. Evidence from
animal studies sheds light on this seemingly counterintuitive effect
of this unique tea-based amino acid. L-theanine administered to
rats by IV in relatively higher doses following the administration of
approximately the same dose of caffeine has been shown to
blunt the stimulating effects of caffeine as assessed by EEG
recordings. However, L-theanine administered in smaller doses on
its own resulted in excitatory stimulation. This reported dual action
of theanine was shown to be dependent on the dose
administered2. Additionally, there are many anecdotal reports of
L-theanine simultaneously enhancing mental alertness, and
some, though not all, preliminary research in humans confirms
this. Previous studies showed that Suntheanine® L-theanine
promotes alpha brain waves, traditionally interpreted as signifying
a relaxed, alert state. In a randomized, placebo-controlled,
crossover study comparing placebo, 50 mg and 200 mg Ltheanine, the higher dose of L-theanine increased power in the
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* These statements have not been evaluated by the Food and Drug Administration.
This product is not intended to diagnose, treat, cure or prevent any disease.
the Operant test in which food is released when the correct lever is
pushed and a light comes on. L-theanine administration to rats resulted in a greater frequency of correct responses when compared
to rats in the control group. In this experiment, the longer the L-theanine was administered, the better the response to the task. Additional tests performed on these animals included the passive and
active avoidance tests. The idea here is that the animals develop
the memory ability to avoid an undesirable outcome. The groups
of animals receiving L-theanine again outperformed the control
groups by exhibiting a greater ability to avoid undesirable events3.
These results demonstrate the memory and learning enhancement
effects of L-theanine.
Furthermore, it seems clear that one of the mechanisms by which
L-theanine supports cognitive health is through its potential antioxidant support for brain cells. Several laboratory investigations
point to L-theanine’s ability to support the health of neurons in the
face of induced oxidative stress. In one such experiment, cultured
rat neurons were exposed to glutamic acid, resulting in significant
cellular death. When these cells were simultaneously exposed to
L-theanine, the cell death was suppressed4. This antioxidant effect
may yield a partial glimpse into Suntheanine’s cognitive performance-enhancing actions.
Suntheanine® L-theanine clearly affects brain activity and is relatively fast acting; however, many of the mechanisms of how it supports cognitive health and brain performance in humans remain
to be fully determined. More recent human clinical studies (2008)
have discovered that the effects of L-theanine on alpha waves are
likely both dose- and caffeine- dependent, as well as dependent
on whether the user is in a resting state or actively performing an
attention-demanding task. This emerging research indicates that
when a large dose of L-theanine is ingested by itself or when it is
ingested in combination with caffeine, L-theanine actually decreases background alpha activity, but promotes attention-related alpha
brain wave processes during difficult attention-demanding tasks.
This decrease in background alpha is associated with significant enhancement of one’s ability to actively perform tasks demanding a
great deal of attention6-8.
Another randomized, placebo-controlled, double blind crossover
study published in 2008 also found differences between L-theanine alone and L-theanine with caffeine on relaxation and cognition. This study investigated the effects of L-theanine (250 mg),
and caffeine (150 mg), in isolation and in combination, in 24 healthy
volunteers who had abstained from caffeine for 12 hours9. Results
were measured 30 and 90 minutes after administration. At 30
minutes, L-theanine alone promoted the participants’ subjective
ratings of “calm” and “relaxed” compared to baseline, while caffeine and L-theanine combined with caffeine both decreased these
feelings.
However, the L-theanine/caffeine combination had significant
positive effects on delayed word recognition reaction time. These
results support the idea that the combination of L-theanine and caffeine may have beneficial effects on cognition and alertness, while
L-theanine alone may promote relaxation9. It therefore seems that
L-theanine has differential effects based on whether it is administered alone or in combination with a stimulant such as caffeine
and can be used either to enhance relaxation and calmness, or to
enhance cognitive performance and alertness.
Helps ease stress and
everyday nervous tension*
In one small investigation, eight
Japanese female university students
were selected as volunteers. Oral
administration of 200 mg of
L-theanine resulted in the generation of alpha brain waves in the occipital and parietal regions of
the brains of the subjects when they were in a resting state, and
resulted in a subjective feeling of relaxation. The intensity of alpha
brain waves was significantly greater in the group of students with
the highest levels of apprehension10.
In a double-blind study illustrating L-theanine’s anti-stress effects,
it was found that a single dose influences both psychological and
physiological states under acute stress. This study gave 12 participants a mental math task as an acute stressor. All participants
underwent four separate trials: one in which they took L-theanine
at the start of an experimental procedure, one in which they took
L-theanine midway, and two control trials in which they either took
a placebo or nothing. L-theanine intake resulted in lower levels of
perceived stress during the math task, a significantly greater reduction in perceived stress from baseline, and a reduction in the heart
rate and salivary immunoglobulin A (a biomarker of stress) responses to the acute stress task relative to the placebo. By analyzing the
heart rate variability, the researchers found that the reductions in
these acute stress responses were likely attributable to the significantly decreased activation of the sympathetic nervous system11.
Another study investigating the anti-stress effects of Ltheanine found that a single dose was able to promote
subjective feelings of tranquility in patients before the onset of
acute nervous tension. The study also investigated the effect of Ltheanine supplementa-tion that followed the onset of
apprehension and found that it did not induce relaxing behavioral
effects. In this double-blind study consisting of 16 subjects, the
researchers obtained behavioral mea-sures of worry in all
participants, both before and after an acute, experimentally
created state of unease. L-theanine was able to promote
‘tranquil’ ratings, as measured on a visual analogue scale in rested
participants. However, when participants were under con-ditions
of increased acute apprehension, L-theanine did not have similar
effects. In comparison, the placebo did not induce any relax-ing
effects at the initial measurement nor after the heightened state
was induced12. It seems L-theanine is an agent that is best used as
a countermeasure to potential situations of nervousness and
tension by supporting mental tranquility. Suntheanine® may
normalize the body’s stress response and condition the body to
handle stressful situations better.
S
Suntheanine® L-theanine has undergone extensive safety
evaluations which include tests for mutagenicity (ability of the
product to induce genetic mutations in DNA) and acute toxicity. In
addition, a 28-day subacute toxicity study and a 78-week
evaluation of toxicity and carcinogenicity of L-theanine have been
conducted in mice.
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* These statements have not been evaluated by the Food and Drug Administration.
This product is not intended to diagnose, treat, cure or prevent any disease.
According to the results of the acute toxicity evaluation, Suntheanine® was reported to have an LD50 of greater than 5,000 mg per
kilogram of body weight. In essence, no toxic effects were noted.
The Ames test for mutagenicity showed Suntheanine® to be nonmutagenic, while no treatment-related side effects were observed
in either the 28-day study or the 78-week evaluation, with findings
indicating a lack of carcinogenic potential of L-theanine 13. In addition, a 90-day toxicity evaluation has been performed on Suntheanine® in which rats were given daily doses of 1500, 3000 or
4000 mg per kilogram of body weight. The no-observed-adverseeffect-level (NOAEL) as determined based on the findings of the
study was established at 4000 mg per kilogram of body weight per
day, the highest dose tested 14.
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Nobre AC, Rao A, Owen
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Kelly SP, Gomez-Ramirez M, Montesi JL, Foxe JJ. J Nutr
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* These statements have not been evaluated by the Food and Drug Administration.
This product is not intended to diagnose, treat, cure or prevent any disease.
Doctor’s Best, Inc
phone: 800-333-6977 • fax: 949-498-3952 • www.drbvitamins.com
© Doctor’s Best, Inc. Revised 08/16