L-theanine Caffeine and Tea


L-theanine and Caffeine.

L-theanine appears to be both very safe and effective. It has a long history of use, an LD50 estimated to be over 1000 times larger than a standard therapeutic dose and no known contraindications with any food or drug. It may well be health-promoting. ref ref ref

The science behind the L-theanine-caffeine combination seems almost equally compelling. L-theanine seems to mitigate the negative aspects of caffeine, such as anxiety, increased blood pressure and diminished sleep quality, while improving upon the positive aspects. Its ability to enhance attention, over and above that of caffeine alone, has been repeatedly verified.

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Are all “L-theanine” preparations the same?

Currently Suntheanine is the only L-theanine preparation known to be 100% L-theanine, the psychoactive isomer. Other preparations may contain up to 50% D-theanine, a non-psychoactive isomer.

Products containing suntheanine

Purebulk claim that their manufacturer’s synthesis is near 100% L-theanine.

Do you build tolerance to the effects of L-theanine?

There isn’t solid research on this question, but there are very few reports of tolerance issues. Tolerance isn’t likely to be an issue for most people taking a standard amount of L-theanine.

L-theanine-Caffeine and Tea

How much L-theanine is in a cup of black tea?

About 20mg (24.2 ± 5.7mg) ref ref

How much caffeine is in a cup of black tea?

14-61mg ref

How much L-theanine is in a cup of green tea?

The exact L-theanine content of teas will depend on environmental conditions (climate, rainfall, sunlight). Standard green tea may have L-theanine content as low as 5mg per cup (7.9 ± 3.8mg). ref While shade grown green tea ( GyokuroMatcha) may have as much as 46mg per cup. ref

How much caffeine is in a cup of green tea?

14-61mg ref

Why pick green tea over black tea?

It’s possible to get more L-theanine per cup with shade grown green tea ( GyokuroMatcha). And catechins in green tea may be pro-cognitive. ref ref

Why pick pure l-theanine and caffeine over green or black tea?

Most studies done on the l-theanine-caffeine combination have a l-theanine to caffeine ratio that isn’t consistent with ratios you would expect from most teas. The studies used about twice as much l-theanine as caffeine by weight. The ratio found in most teas is reversed, with the possible exception of high quality green