Theanine Reduces Anxiety, Improves Attention

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Theanine (L-theanine), which is found in tea leaves, may reduce anxiety and improve attention and the ability to focus in people who have high anxiety levels. Japanese researchers reported these findings in a recent issue of the Journal of Functional Foods.

Theanine directly affects the brain

Theanine is an amino acid that has a chemical structure similar to glutamate, a neurotransmitter that plays a role in memory. Previous studies have shown that theanine can pass through the blood-brain barrier, and thus can have a direct impact on the brain.

In fact, theanine has demonstrated an ability to protect against neuronal cell death after transient cerebral ischemia. A recent study published in Pharmacological Research also shows that elderly volunteers with normal or slight cognitive dysfunction who took powdered green tea with a high theanine content had significantly lower decline in cognitive function when compared with a placebo group.

In the new current study, investigators administered the manifest anxiety scale (MAS) to 18 healthy university students. Students were classified as being either high-anxiety or low-anxiety.

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Both groups were given water or water plus 200 mg of L-theanine per 100 mL of water. The test was conducted repeatedly and evaluations were done between 15 and 60 minutes after the students ingested the water or water plus theanine.

Results indicated that students who were highly anxious and who received theanine had a slowed heart rate, improved attention, and better reactions time when compared with high-anxiety students who took the placebo. Students with low anxiety did not experience any significant benefit from taking theanine.

The study’s authors concluded that “200 mg of L-theanine intake may help normal people with high anxiety propensity to concentrate on their daily activities.” Although tea leaves contains theanine, it is at such a low concentration (less than 2%) that people cannot drink enough tea to get an effective dose of 100 to 200 mg daily. Therefore a supplement is required.

Unlike other conventional treatments for anxiety, noted the authors, theanine does not cause drowsiness, impair concentration, or slow down reflexes. Rather, 200 mg of theanine “enhanced performance in visual attention task, and reaction time response, among the subjects with higher anxiety propensity symptoms.”

SOURCES:
Higashiyama A et al. Journal of Functional Foods 2011; doi:10.1016/j.jff.2011.03.009
Kakuda T. Pharmacological Research 2011 Apr 6

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