Roll Call

“Theanine?”Here!L-theanine

Plant

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As a supplement

Talk to your doctor or pharmacist.

Roll Call does not check drug interactions or assess personal safety.

An amino acid found naturally in tea leaves, sold as an isolated compound in supplement form.

Why it’s used

Taken to support relaxation and calm focus, often alongside caffeine for attention-related tasks.

What the evidence is for

acute measures of relaxation and attention, often combined with caffeine.

What the evidence says

Small clinical studies suggest theanine, alone or combined with caffeine, may modestly affect measures of alertness and relaxation-related brain activity (alpha waves), but sample sizes are generally small and effects are modest. It is not covered by an NIH Office of Dietary Supplements fact sheet, and larger confirmatory trials are limited.

Dose studied

100–400 mg — doses used in relaxation and cognitive performance studies.

Context

Studied doses in relaxation and cognitive-performance trials have generally ranged from about 100 to 400 milligrams per day, sometimes as a single dose paired with caffeine.

Rumors

  1. Acute measures of relaxation and attention, often combined with caffeine.

    Not gradedhealth and safety evidence

    Sources cited — no verdict reached.

    What was measured is not yet noted.