L-Theanine
Overview:
Theanine is a glutamic acid analog or amino acid derivative commonly found in tea (infusions of Camellia sinensis), and also in the basidiomycete mushroom Boletus badius . In 1950 the Tea laboratory of Kyoto successfully separated theanine from Gyokuro leaf, which has the highest theanine content among all teas. Theanine is an analog to glutamine and glutamate, and can cross the blood-brain barrier. It is sold in the US as a dietary supplement and is FDA confirmed as GRAS. The Japanese Ministry of Health and Welfare approved the use of L-theanine (the levorotary enantiomer of theanine) in 1964.
Effects on the brain
Able to cross the blood-brain barrier, theanine has psychoactive properties. Theanine has been shown to reduce mental and physical stress, and improves cognition and mood in a synergistic manner with caffeine.
While structurally related to the excitatory neurotransmitter glutamate, theanine only has weak affinity for the glutamate receptor on post-synaptic cells. Rather, its primary effect seems to increase the overall level of the brain inhibitory transmitter GABA. Theanine also increases brain dopamine levels and has micromolar affinities for AMPA, Kainate and NMDA receptors. Its effect on serotonin is still a matter of debate in the scientific community, with studies showing increases and decreases in brain serotonin levels using similar experimental protocols.It has also been found that injecting spontaneously hypertensive mice with theanine significantly lowered levels of 5-hydroxyindoles in the brain. Researchers also speculate that it may inhibit glutamic acid excitotoxicity.Theanine also promotes alpha wave production in the brain.
Studies on test rats have shown that even repeated, extremely high doses of theanine cause little to no harmful psychological or physical effects. Theanine showed neuroprotective effects in one rat study.
Several beverage manufacturers are selling drinks containing theanine and are marketing them as drinks that help people focus and concentrate.
Immune system benefits
L-Theanine may help the body's immune response to infection by boosting the disease-fighting capacity of gamma delta T cells. The study, published in 2003 by the Brigham and Women's Hospital, included a four-week trial with 11 coffee drinkers and 10 tea drinkers, who consumed 600 milliliters of coffee or black tea daily. Blood sample analysis found that the production of anti-bacterial proteins was up to five times higher in the tea-drinkers, an indicator of a stronger immune response.
According to a study conducted by researchers at Johns Hopkins University, when gophers were given 25 milligrams of theanine twice daily for three weeks there were increased levels of theta waves within the hypothalamus, indicating improved cognition and memory versus placebo.
L-theanine may boost attention for anxious folks: Study
Related topics: Research, Proteins, peptides, amino acids, Cognitive and mental function
Daily supplements of L-theanine, an amino acid found in tea, may help people with anxiety focus on their daily activities, suggests a new study from Japan.
On the other hand, people with minimal anxiety levels did not experience any benefits from supplementation, according to findings published in the Journal of Functional Foods.
“Given that L-theanine is a relaxant, it is directly or indirectly involved at the neurochemical level and thus it is impacted by a number of neurotransmitter systems,” wrote the scientists from the University of Shiga Prefecture and Taiyo Kagaku.
“Therefore, 200 mg of L-theanine intake may help normal people with high anxiety propensity to concentrate on their daily activities.”
The study used Taiyo Kagaku’s Suntheanine-branded L-theanine ingredient, and the Japanese company funded the study.
Relax and focus
L-theanine, an amino acid found in tea leaves, is thought to help reduce stress, promote relaxation and improve the quality of sleep. L-theanine is found in tea leaves in low concentrations (less than 2 percent), which means that effective dosage levels (of 100 – 200mg/day) cannot be delivered from drinking tea.
Various health effects have been associated with L-theanine, including relaxation, neuroprotective effects, and improved attention.
During rest, L-theanine increases alpha activity in EEG models - suggesting greater relaxation. Whilst the amino acid is known to induce changes in alpha activity that indicates increased attentional processing during tasks that require attention.
The new study confirmed the dose of 200 mg for “enhanced performance in visual attention task, and reaction time response, among the subjects with higher anxiety propensity symptoms”.
Study details
The Japanese researchers recruited 18 healthy University students and assessed their anxiety levels using the manifest anxiety scale (MAS).
Student with high anxiety were put in one group, while students with minimal anxiety were put in another group. Both groups received water or water plus 200 mg of L-theanine per 100 ml of water. The test was performed repeatedly and assessments performed between 15 and 60 minutes after ingestion.
Results showed that highly anxious students receiving the L-theanine displayed a slowing of their heart rate, improved attentional performance, and better reaction times, compared to members of the same group receiving placebo.
No significant benefits were observed in the student with minimal anxiety.
“It is noteworthy to mention that unlike other conventional anti-anxiety treatments, L-theanine did not result in increased drowsiness, slowed reflexes, or impaired concentration,” wrote the authors.
“Results of a present study showed that ingestion of 200 mg of L-theanine changes the electrical activity in the brain by increasing alpha electric band measured by EEG.”
Source: Journal of Functional Foods Published online ahead of print, doi: 10.1016/j.jff.2011.03.009 “Effects of L-theanine on attention and reaction time response” Authors: A. Higashiyama, H.H. Htay, M. Ozeki, L.R. Juneja, M.P. Kapoor