L-Theanine - Stuff in Green Tea is available as a supplement. I add an extra 200 mg to my mug of green/white tea that I drink twice each day.

jackD

Theanine is an amino acid found in green tea that produces
tranquilizing effects in the brain. In Japan, soft drinks and
chewing gum are spiked with theanine for the purpose of
inducing relaxation.

Although theanine creates a feeling of
relaxation, it doesn't shut down the brain. Studies on rodents
show that theanine enhances the ability to learn and remember.
By shutting off worry central, theanine appears to increase
concentration and focus thought.

Theanine is different than kava-kava in that it doesn't cause
drowsiness, just relaxation. Theanine increases GABA, while
caffeine decreases it. GABA doesn't just relax, it also
creates a sense of well-being. Theanine's ability to increase
this brain chemical can literally put you in a better mood.
Theanine also increases levels of dopamine, another brain
chemical with mood-enhancing effects.

Protecting neurons
In studies on neurons in cell culture, theanine significantly
reverses glutamate-induced toxicity. In vivo studies show the
same effect in rodents. Glutamate-induced neuro-toxicity is a
major cause of degenerative brain disease.

Many Americans suffer from slightly elevated blood pressure,
but don't know they have it. Chronic high blood pressure
inflicts damage on the delicate cerebral vascular network and
increases the risk of stroke. Theanine has been shown to help
lower blood pressure.

Theanine readily crosses the blood-brain barrier and changes
brain chemistry in a way that has been compared to
aromatherapy. Studies show that theanine is a non-toxic,
highly desirable mood modulator.


1: Biol Pharm Bull. 2002 Dec;25(12):1513-8.

Neuroprotective effects of the green tea components theanine and catechins.

Kakuda T.

Central Research Institute, Itoen, Ltd, Shuzuoka, Japan.

The neuroprotective effects of theanine and catechins contained in green tea are
discussed. Although the death of cultured rat cortical neurons was induced by
the application of glutamic acid, this neuronal death was suppressed with
exposure to theanine. The death of hippocampal CA1 pyramidal neurons caused by
transient forebrain ischemia in the gerbil was inhibited with the ventricular
preadministration of theanine. The neuronal death of the hippocampal CA3 region
by kainate was also prevented by the administration of theanine. Theanine has a
higher binding capacity for the AMPA/kainate receptors than for NMDA receptors,
although the binding capacity in all cases is markedly less than that of
glutamic acid.

The results of the present study suggest that the mechanism of
the neuroprotective effect of theanine is related not only to the glutamate
receptor but also to other mechanisms such as the glutamate transporter,
although further studies are needed. One of the onset mechanisms for
arteriosclerosis, a major factor in ischemic cerebrovascular disease, is
probably the oxidative alteration of low-density lipoprotein (LDL) by active
oxygen species. The oxidative alterations of LDL were shown to be prevented by
tea catechins. Scavenging of *O(2)(-) was also exhibited by tea catechins.
The
neuroprotective effects of theanine and catechins contained in green tea are a
focus of considerable attention, and further studies are warranted.

Publication Types:
Review
Review, Tutorial

PMID: 12499631 [PubMed - indexed for MEDLINE]