L-Theanine

Story

Connected to · 2

synergy · 1

Caffeine + L-Theanine
Theanine is studied most not on its own but together with caffeine: in Owen 2008, 100 mg of theanine with 50 mg of caffeine made attention switching more accurate and people less easily distracted than placebo; but the trial had no theanine-only group, so it cannot say how much of the effect belongs to theanine. That it takes the edge off caffeine's jitters is a common marketing claim these trials did not measure.

contrast · 1

L-Tyrosine
Theanine also enters the brain through the LAT1 transporter, but it acts on excitatory signals such as glutamate, not on the stores of dopamine and norepinephrine. Same entrance, different targets once inside.

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What L-theanine is

EVIDENCERCT 1 · MECH 4

READ THE ORIGINAL

The calm, unhurried feeling after a cup of tea is often credited to one amino acid in it: L-theanine. It is found almost only in the tea plant (Camellia sinensis), and the body does not use it to build protein, which is why it is called a non-protein amino acid.

Its shape resembles two of the brain's most basic signaling molecules: glutamate, which excites nerve cells, and (gamma-aminobutyric acid), which quiets them. Because it looks like an amino acid, it can ride a carrier in the blood-brain barrier that ferries large amino acids from the blood into the brain, called LAT1; that step comes from animal studies. In people who swallow it, the level in the blood peaks roughly 30-50 minutes later.

What matters for you: tea really does contain it, but a cup of tea holds more caffeine than theanine, so the feeling of drinking tea cannot be credited to theanine alone.

Educational content, not medical advice — consult a clinician.

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L-Theanine

Story

Connected to · 2

synergy · 1

Caffeine + L-Theanine
Theanine is studied most not on its own but together with caffeine: in Owen 2008, 100 mg of theanine with 50 mg of caffeine made attention switching more accurate and people less easily distracted than placebo; but the trial had no theanine-only group, so it cannot say how much of the effect belongs to theanine. That it takes the edge off caffeine's jitters is a common marketing claim these trials did not measure.

contrast · 1

L-Tyrosine
Theanine also enters the brain through the LAT1 transporter, but it acts on excitatory signals such as glutamate, not on the stores of dopamine and norepinephrine. Same entrance, different targets once inside.

Read full story

Stop 1/5

What L-theanine is

EVIDENCERCT 1 · MECH 4

READ THE ORIGINAL

The calm, unhurried feeling after a cup of tea is often credited to one amino acid in it: L-theanine. It is found almost only in the tea plant (Camellia sinensis), and the body does not use it to build protein, which is why it is called a non-protein amino acid.

Its shape resembles two of the brain's most basic signaling molecules: glutamate, which excites nerve cells, and (gamma-aminobutyric acid), which quiets them. Because it looks like an amino acid, it can ride a carrier in the blood-brain barrier that ferries large amino acids from the blood into the brain, called LAT1; that step comes from animal studies. In people who swallow it, the level in the blood peaks roughly 30-50 minutes later.

What matters for you: tea really does contain it, but a cup of tea holds more caffeine than theanine, so the feeling of drinking tea cannot be credited to theanine alone.

Educational content, not medical advice — consult a clinician.