Virtually everyone has stress. In fact, According to
the Stress in America™ survey by the American Psychological
Association,1 39 percent of respondents
said their stress increased over the past year, and
44 percent said that their stress had increased
over the past five years. The question is, how well do you handle
your stress, how does it affect your life, and what can you
do about it? The same Stress in America survey indicates the
following percentage of Americans is only fair or poor at:
- Preventing themselves from becoming stressed (44 percent)
- Managing or reducing stress once experienced (39 percent)
- Recovering fully or recharging after they’ve been stressed (31 percent)
The ramifications of chronic stress include increases in illness,
including headaches, heart disease, immune deficiencies and
digestive problems. To a large extent, this appears to be due
to an increased production of stress hormones and decreased
So what can be done to help control stress and reduce its
ill effects? The answer is really multifaceted and may include a
program of diet, exercise, stress-management techniques such
as yoga, and even psychological counseling. In addition, when
stress rears its ugly head, nature’s chill pill, L-theanine may be
able to help.
L-THEANINE’S MECHANISM OF ACTION
Asian cultures have often used teas for relaxation effects. The
relaxing effect is, at least in part, caused by the presence of a
neurologically active amino acid, L-theanine (gamma-ethyl-amino-
L-glutamic acid). Tea has the reputation of having less caffeine
than coffee but it is the L-theanine in the tea that lessens
the stimulant effect of caffeine on the human nervous system.
In the brain, L-theanine increases both serotonin and dopamine
production3, and possibly GABA as well.4
Evidence from human electroencephalograph (EEG) studies
show that it also significantly increases brain activity in the
alpha frequency band which indicates that it relaxes the mind
without inducing drowsiness. Alpha activity is also known to
play an important role in critical aspects of attention. Research
indicates that L-theanine has a significant effect on improving
mental alertness while promoting relaxation.5
L-THEANINE AND RELAXATION
According to Mason, two small human studies6 showed that
within 30–40 minutes of consuming 50 or 200 mg of L-theanine
there is an increase of alpha wave activity/electrical signals produced
by the brain. The perceived relaxation effect in the subjects
coincided with the detection of alpha waves. This shows
that L-theanine fosters a state of alert relaxation, which is consistent
with the fact that anxious people have fewer or smaller
The journal Human Psychopharmacology Clinical and Experimental
published a double-blind placebo-controlled study7 in
which sixteen healthy volunteers received 200 mg L-theanine,
a pharmaceutical anxiolytic or placebo. The results showed that
L-theanine induced feelings of tranquility in the volunteers.
L-THEANINE, STRESS AND ANXIETY
The journal Biological Psychology published a double-blind,
placebo-controlled study8 in which twelve participants underwent
four separate trials: one in which they took L-theanine at
the start of an experimental, stress-inducing procedure, one in
which they took L-theanine midway, and two control trials in
which they either took a placebo or nothing. The results showed
that L-theanine intake resulted in a reduction in some physiological
indicators of stress within 15 minutes, compared to the
placebo or control condition. Moreover, analyses of heart rate
variability indicated that reductions in heart rate were likely attributable
to a reduction of sympathetic nervous activation, suggesting
that L-theanine had anti-stress effects via the inhibition
of cortical neuron excitation.
Similarly, a placebo-controlled study9 conducted with pharmacy students found that L-theanine (200 mg, twice a day,
after breakfast and lunch) was effective at suppressing the initial
stress response of students.
The Journal of Physiological Anthropology published a placebo-
controlled study10 in which 14 participants took either
L-theanine + placebo, caffeine + placebo, or placebo only (L-theanine
200 mg, caffeine 100 mg) while performing mental
tasks and physiological activities under conditions of physical
or psychological stress. The results showed that L-theanine
significantly reduced anxiety and reduced the blood-pressure
increase in high-stress-response adults. Caffeine tended to
have a similar but smaller inhibition of the blood-pressure increases
caused by the mental tasks.
The Journal of Functional Foods published a double-blind,
placebo-controlled study11 in which 18 normal healthy subjects
were divided into two groups referred to as high anxiety propensity
group and the minimal anxiety propensity group. Both
groups received 200 mg L-theanine and placebo (at different
times)(200 mg/100 ml water) and placebo (100 ml water) in
a double-blind repeated measurement design protocol. When
tested at 15–60 minutes after consumption, results showed
significantly enhanced activity of alpha bands, descending
heart rate, elevated visual attentional performance, and improved
reaction time response among high anxiety propensity
subjects compared to a placebo. However, no significant differences
were noticed among subjects with a minimal anxiety
L-THEANINE AND MENTAL FOCUS
The journal Neuropharmacology published a double-blind, randomized,
cross-over study12 in which 27 participants received
100 mg L-theanine, 50 mg caffeine, a combination of the two,
or a placebo. The results were that L-theanine and caffeine each
significantly reduced error rates during a sustained attention
task. It was noted that the combination of L-theanine and caffeine
did not confer any additional benefits over either compound
Another study13 examined “sensory gating.” Sensory gating
describes the processes of filtering out redundant or unnecessary
stimuli in the brain from all possible environmental stimuli.
Being able to do this is obviously beneficial when you’re trying
to focus on a mental task. In the study, L-theanine was given
to 14 healthy subjects, and tests were conducted 90 minutes
later. The results were that 200 mg and 400 mg significantly
improved sensory gating.
Research shows that L-theanine is effective at helping to promote
relaxation while reducing feelings of stress and anxiety.
Furthermore, this amino acid is even helpful in promoting
mental focus. Truly, L-theanine is nature’s chill pill.
- American Psychological Association. Stress in America™: Our Health at Risk. Released January 11, 2012. 78 pgs.
- Head KA, Kelly GS. Nutrients and botanicals for treatment of stress: adrenal fatigue, neurotransmitter imbalance, anxiety, and restless sleep. Altern Med Rev. 2009 Jun;14(2):114–40.
- L-Theanine monograph. Alternative Medicine Review 2005;10(2):136-8.
- Lu K, Gray MA, Oliver C, et al. The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans. Hum Psychopharmacol Clin Exp 2004;19:457–65.
- Nobre AC, Rao A, Owen GN. L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr 2008;17 Suppl 1:167–8.
- Mason,R. 200 mg of Zen. Alternative & Complementary Therapies 2001; 7(2):91–95.
- Ibid. Lu K, Gray MA, Oliver C, et al.
- Kimura K, Ozeki M, Juneja LR, Ohira H. L-Theanine reduces psychological and physiological stress responses. Biol Psychol 2007;74(1):39–45
- Unno K, Tanida N, Ishii N, et al. Anti-stress effect of theanine on students during pharmacy practice: positive correlation among salivary á-amylase activity, trait anxiety and subjective stress. Pharmacol Biochem Behav. 2013 Oct;111:128–35.
- Yoto A, Motoki M, Murao S, Yokogoshi H. Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses. J Physiol Anthropol. 2012 Oct 29;31:28.
- Higashyama A, Htay HH, Ozeki M, Juneja LR, Kapoor MP. Effects of l-theanine on attention and reaction time response. Journal of Functional Foods. 2011;3(3):171–8.
- Foxe JJ, Morie KP, Laud PJ, Rowson MJ, de Bruin EA, Kelly SP. Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task. Neuropharmacology. 2012 Jun;62(7):2320–7.
- Ota M, Wakabayashi C, Matsuo J, et al. Effect of L-theanine on sensorimotor gating in healthy human subjects. Psychiatry Clin Neurosci. 2014 May;68(5):337–43.