L-Theanine in Green Tea: Anxiety Reducer and Mood Enhancer

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L-Theanine in Green Tea: Anxiety Reducer and Mood Enhancer

JoAnn Guest

Nov 09, 2006 18:19 PST

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How a Unique Anxiety Reducer and Mood Enhancer Increases Alpha Waves

 

http://www.brain.web-us.com/l-theanine_anxiety_reducer.htm

L - Theanine in Green Tea

by Carolyn Perrini, CLS, CNC

 

Hundreds of studies exist showing the many health benefits of green

tea. But what makes it the most consumed beverage in the world after

water is its pleasant taste and relaxation effect. Both of these

qualities-and more-can be traced to a unique, neurologically-active

amino acid in tea called L-theanine(gamma-ethylamino-L-glutamic

acid).

 

L-theanine is a free (non-protein) amino acid found almost

exclusively

in tea plants (Camellia sp.), constituting between 1 and 2-percent

of the dry weight of tea leaves. It is the predominant amino acid in

green tea leaves, giving tea its characteristic umami or " 5th taste "

(besides the four traditional tastes: sweet,salty, acid, and bitter).

 

Attempts to isolate the L-theanine, with its physical and

neurological benefits, from the tea leaves were once difficult,

expensive,and inefficient. Economically feasible methods of

producing the identical

L-theanine now exist and do not require a mountain of tea leaves.

 

Physiological Effects

 

The calming effect of green tea may seem contradictory to the

stimulatory property of tea's caffeine content but it can be

explained

by the action of L-theanine. This amino acid actually acts

antagonistically against the stimulatory effects of caffeine on the

nervous system.

 

Research on human volunteers has demonstrated that L-theanine

creates a

sense of relaxation in approximately 30-40 minutes after ingestion

via

at least two different mechanisms. First, this amino acid directly

stimulates the production of alpha brain waves, creating a state of

deep

relaxation and mental alertness similar to

what is achieved through meditation.

 

Second, L-theanine is involved in the formation of the inhibitory

neurotransmitter, gamma amino butyric acid (GABA).

 

GABA influences the levels of two other neurotransmitters, dopamine

and

serotonin, producing the key relaxation effect.

 

Alpha Brain Activity

The brain emits weak electrical impulses (brain waves) that can be

measured on the surface of the head. The predominant frequency of

electrical impulses correlates with different types of mental states

and

activities.

 

Brain waves are classified into four categories (delta, theta,

alpha,

and beta)-each with an associated mental state (Fig. 1).

 

Delta is seen only in the deepest stages of sleep. Theta is seen in

light sleep and drowsiness. Alpha is present in

wakefulness where there is a relaxed and effortless alertness and

Beta

is seen in highly stressful situations and where there is difficulty

in

mental concentration and focus.

 

It is well known that alpha brain waves are generated during a

relaxed

state and therefore alpha waves are used as an index of relaxation.

 

 

In one study of these mental responses to L-theanine, brain wave

topography showed that alpha waves were observed from the back to

the

top of a person's head (occipital and parietal regions of the brain)

within approximately 40 minutes after the subjects had taken either

50

or 200 mg of L-theanine. In a separate study, the intensity of alpha

waves were determined to be dose dependent (with a 200 mg dose

showing a

significant increase over controls) and

detectable after 30 minutes.

 

Additional Benefits

L-theanine has a significant effect on the release or reduction of

neurotransmitters like dopamine and serotonin, resulting in improved

memory and learning ability. L-theanine may also influence emotions

due

to its effects on the increased release of dopamine.

 

L-theanine reduces brain serotonin concentration by either

curtailing

serotonin synthesis or increasing degradation

in the brain.

 

The regulation of blood pressure is partly dependent upon

catecholaminergic and serotonergic neurons in both the brain and the

peripheral nervous system.

 

Studies on spontaneously hypertensive rats (SHR) showed an

impressive

blood pressure lowering effect with L-theanine.

 

The lowered blood pressure effect was dose-dependent with the

highest

test dose creating the most significant drop.

 

L-glutamine was used as one of the controls. Although L-glutamine is

similar in chemical structure to L-theanine, it did not exhibit an

anti-hypertensive effect

(Fig. 2). (3)

 

 

Preliminary studies report that L-theanine has been found to

increase

the anti-tumor activity of some chemotherapeutic agents (doxorubicin

and

idarubicin) and to ameliorate some of the side effects of these

drugs.

 

It appears to increase the inhibitory concentration of these drugs

in

the tumor cells,although the mechanism is not known. At the same

time,

L-theanine decreased oxidative stress caused by these agents on the

normal cells, possibly due to its mild antioxidant activity. In this

regard, L-theanine has been shown to inhibit

lipid peroxidation, catalyzed by copper, in low-density lipoprotein

(LDL) in vitro.

 

Stress Relief

Stress and anxiety are debilitating conditions that upset the

balance of

our hormones leading to a loss of our well-being, performance, and

even

lifespan.

 

Stress impairs the immune system, leaving us vulnerable to

opportunistic

infections, and can cause depression. In 1998, pharmaceutical sales

of

anti-anxiety drugs totaled over 700 million dollars, while sales of

antidepressants totaled close to 5 billion dollars!

 

People under stress can mitigate many of the harmful effects of

stress

with L-theanine without becoming sedated in the process. L-theanine

doesn't make one drowsy, nor does it promote

sleep because this amino acid does not produce theta waves in the

brain.

 

It should be noted that if an individual were already relaxed,

taking

L-theanine would not produce further relaxation.

 

Status and Usage

L-theanine has just recently been introduced to the U.S. market.

Japan

is credited with most of the clinical studies and information we

possess

thus far on L-theanine but research is ongoing.

 

We do know that it is absorbed from the small intestine via a

sodium-coupled active transport process. It crosses the

blood-brain barrier, as evidenced by the mental effects.

 

L-theanine competes for absorption in the intestinal tract and the

brain

with the amino acids found in the methionine group (leucine,

isoleucine,

and valine), however the concentrations of amino acids are unchanged

by

simultaneous ingestion of L-theanine.

 

L-theanine is extremely safe. There are no dietary limits on L-

theanine

intake by the Japan Food Additive Association. In 1964, the Japanese

Ministry of Health and Welfare approved L-theanine for unlimited use

in

all foods, with the exception of infant foods.

 

The intended use of L-theanine is that of a mental and physical

relaxant

that does not induce drowsiness. Although there is no set schedule

for

taking L-theanine, it may generally be taken at the first signs of

stress.

 

Based on the results of the clinical studies, L-theanine is most

effective in the range of 50-200 mg, with the effect being felt

within

30 minutes and lasting for 8-10 hours.

 

Individuals with high stress levels may increase their dosage of

L-theanine to at least 100 mg, with no more than 600 mg being taken

in a

six hour period. FDA recommends a maximum dose of 1200 mg daily,

although the reason for this limit is not clear, due to its

demonstrated

safety.

 

There are no known adverse reactions to L-theanine and no drug

interactions have been reported. L-theanine is not affected by food

and

may be taken anytime, as needed.

 

Because it has a mild taste, capsules may be opened and dissolved in

water. Although it is probably safe for pregnant women and nursing

mothers, we discourage its use by them pending conclusive research.

 

Conclusion

Research into L-theanine derived from the contradictory observation

that

green tea, with its high caffeine content, produces a very calming

effect.

 

The seemingly multi-dimensional reasons for this relaxation effect

will

continue to be studied. Current areas of ongoing research include

using

L-theanine as an alternative to Ritalin in children and adults, as a

treatment for PMS, in controlling certain conditions of high blood

pressure, in sharpening mental

acuity and concentration, and as an anti-cancer agent alone and in

synergy with other cancer-fighting agents.

 

L-theanine may find another area of application for its use as a

supplement in reducing the negative side effects of caffeine

brought on by the over-consumption of coffee, soft drinks, or other

caffeine-containing substances.

 

References

1. Kakuda T, Nozawa A, Unno T, et al. Inhibiting effects of theanine

on

caffeine stimulation evaluated by EEG in the rat. Biosci Biotechno

Biochem 2000;

64:287-293.

2. Mason R. 200 mg of Zen; L-theanine boosts alpha waves, promotes

alert

relaxation. Alternative & Complementary Therapies 2001,April; 7:91-95

3. Juneja LR, Chu D-C, Okubo T, et al. L-theanine a unique amino

acid of

green

tea and its relaxation effect in humans. Trends Food Sci Tech 1999;

10:199-204.

4. Yokozawa T, Dong E. Influence of green tea and its three major

components

upon low-density lipoprotein oxidation. Exp Toxicol Pathol 1997;

49(5):329-335.

 

 

JoAnn Guest

mrsjo-

www.geocities.com/mrsjoguest/Diets