Theanine
L-theanine is an amino acid that the tea plant makes and almost no other food contains. It gives tea part of its savory taste. The body does not need it, and the doses tested in studies come from supplements.
200 mgthe single dose most used in studies, not a daily need
50 - 400 mg the range tested in human trials
EU health claims · none accepted for calm, sleep or mental performance
- Main source Tea leaves green, black, white and oolong
- Most in Shaded teas such as gyokuro and matcha
- Related to Glutamine with an extra ethyl group
- Evidence Weak small, short trials
Doses as used in published human trials; EU status from the EFSA opinion of 2011. Not a recommended amount.
Where Theanine Comes From
One plant supplies nearly all of it. How much ends up in your cup depends on the leaf, how it was grown and how long you brew it.
- Shade-grown green teagyokuro and matcha are grown under cover for weeks before picking, which keeps more theanine in the leaf; with matcha you also drink the powdered leaf itself
- Other green, white, oolong and black teaall come from the same plant and all contain some; young buds and leaves hold more than older ones
- Herbal teaschamomile, mint and rooibos are not from the tea plant and contain none
- Supplementscapsules and drinks with L-theanine, sometimes with added caffeine, give the 50 to 400 mg doses used in studies
What Is Theanine?
L-theanine is a close relative of glutamine, with an ethyl group attached. The tea plant makes it in its roots and sends it to the young leaves, where it is one of the most plentiful amino acids. It is a large part of the brothy, savory taste, called umami, that good green tea has.
How Sunlight Lowers Theanine in Tea
In leaves exposed to sun, the plant breaks theanine down and uses its parts to build catechins, the bitter, astringent polyphenols of tea. Japanese growers shade tea bushes for a few weeks before the harvest of gyokuro and matcha to slow this down. The result is a sweeter, more savory tea with more theanine and fewer catechins than the same plant grown in full sun.
What Theanine Does in the Body
Theanine is absorbed from the gut and crosses into the brain. Because its shape resembles glutamate, the brain's main excitatory messenger, researchers have studied whether it changes brain signaling. In small studies it raised alpha brain waves, a pattern linked with relaxed wakefulness, but whether that changes how people feel or perform is less clear.
What Human Studies Show About Theanine
Most trials are small, last a day to a few weeks and use 200 mg or so. Results on stress, calm and sleep are mixed. In 2011 EFSA reviewed the evidence for claims that L-theanine improves mental performance, eases stress, supports normal sleep or reduces menstrual discomfort, and found a cause and effect had not been shown for any of them.
Several studies gave theanine together with caffeine, as tea does, and found slightly better attention on some tasks than with caffeine alone. The caffeine in these products still counts toward your daily caffeine.
Common Theanine Mistakes
Treating it as a sleeping pill. Theanine is not a sedative. In the trials it did not make people drowsy, and EFSA found no proof that it improves sleep.
Expecting a cup of tea to match a capsule. Most trials used about 200 mg, more than a usual cup of tea provides.
Theanine Supplements
Supplements are the main source of theanine at the doses studied.
Types of Theanine Supplements
- L-theaninethe form found in tea and used in most trials
- Branded L-theanine, such as Suntheaninethe same molecule made by a specific process; several trials used it
- Theanine with caffeinecommon in focus and energy products; read the caffeine figure too
Theanine Safety
Short trials report few side effects. Use over months, in pregnancy and while breastfeeding has not been studied well. Ask a doctor first if you take medicine for blood pressure, anxiety or sleep.
Sources: EFSA opinion on L-theanine health claims (2011), published reviews of human trials. Not medical advice.
Tracking Theanine in Caltide
- Not totaled yetCaltide does not add up theanine yet. The caffeine in the drinks you log is counted and shown in the Nutrition tab, and every food has its full breakdown in the food library.
Related Nutrients
Theanine Sources and References
The figures and claims on this page are checked against these sources.
Questions About Theanine
An amino acid made by the tea plant (Camellia sinensis) and almost no other food. It is not used to build protein and the body does not need it, but it reaches the brain after you drink tea or take a supplement.
The evidence is weak. Small, short trials report mixed effects on stress and calm, and EFSA found that a cause and effect for relieving stress or improving sleep had not been shown.
Shade-grown green teas such as gyokuro and matcha tend to have the most, because shading the bushes before harvest slows the conversion of theanine into bitter catechins. Amounts vary widely by leaf, grade and brewing.
No. Theanine comes from the tea plant, so coffee, cocoa and energy drinks contain none unless it is added, as some energy drinks and pre-workout products do.
Because tea contains both. Small studies gave the two together and found slightly better attention on some tasks than with caffeine alone, but results differ between studies and EFSA did not accept a claim for mental performance.
About 50 to 400 mg a day, with 200 mg the most common. That is a studied range, not a recommended amount, and 200 mg is more than a usual cup of tea provides.
Short studies report few side effects. Its safety over months, in pregnancy and with medicines that lower blood pressure or act on the brain has not been studied well, so ask a doctor before combining them.
Track anywhere. On any device.
Your calorie counter and food diary in your pocket, free and without ads, with Tide one tap away.
- Log by photo, barcode or voice, right where you eat
- Steps and workouts from Apple Health and Health Connect
- The same log on your phone and in your browser, always in sync