Theanine

non-nutrient/non-botanicalTheanine glucoside

Best before bed

What is it

L-theanine is an amino acid naturally found in tea leaves, valued for its ability to promote a calm, focused mental state without causing drowsiness. It is commonly taken on its own or paired with caffeine.

How it works

L-theanine crosses the blood-brain barrier within about 30 to 60 minutes of ingestion. It increases alpha brain wave activity — associated with relaxed alertness — and modulates neurotransmitters including GABA, dopamine, and serotonin. In animal studies it also raises BDNF (brain-derived neurotrophic factor). The most consistent subjective effect in humans is a calm, focused mental state. When combined with caffeine, theanine smooths out the jittery edge of caffeine and may improve sustained attention compared to caffeine alone.

Evidence for 5 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Stress and anxiety

Grade B

Good evidence

200 to 400 mg per day reduces stress and anxiety markers in several trials. Effects are gentler than prescription medications.

Attention with caffeine

Grade B

Good evidence

Combined with caffeine, improves sustained attention and reaction time more than caffeine alone, with less jitteriness.

Sleep quality

Grade C

Moderate evidence

Modest improvement in sleep quality (not necessarily duration) at 200 to 400 mg before bed.

Acute cognitive performance

Grade C

Moderate evidence

May modestly improve cognitive performance, especially in stressed or fatigued individuals.

Blood pressure (stress-related)

Grade C

Moderate evidence

Small reductions in stress-induced blood pressure in some trials.

Dosage

Typical doses are 100 to 400 mg per day, with 200 mg being the single dose most studied for acute effects. A cup of green tea provides about 25 to 60 mg. Doses up to 900 mg per day have been used short-term in research without notable safety concerns.

When and how to take it

L-theanine is often taken in the evening for sleep support or anytime during the day for stress and focus. Effects begin within 30 to 60 minutes and last several hours. The 1:1 or 1:2 ratio of L-theanine to caffeine is popular for daytime focused energy. For sleep, 200 mg taken 30 to 60 minutes before bed is common.

Food sources

Food	Amount	%DV
Green tea (brewed), 1 cup	25-60 mg	—
Black tea (brewed), 1 cup	15-25 mg	—
White tea (brewed), 1 cup	30-50 mg	—
Matcha (1 g)	10-20 mg	—

Safety

L-theanine is well tolerated with few side effects. Mild headache or relaxation that some perceive as drowsiness can occur at higher doses. It does not cause physiological sedation like benzodiazepines do. The FDA considers it GRAS (generally recognized as safe) for food use.

Who should be cautious

People on antihypertensive medications should monitor blood pressure when starting theanine. Pregnant and breastfeeding women should consult their doctor due to limited specific safety data, though normal green tea consumption is not problematic.

Interactions

May modestly enhance blood-pressure-lowering medications. The interaction with caffeine is intentional and well tolerated. No major interactions with prescription drugs are known, though long-term safety data at high doses is limited.

Frequently asked questions

Does theanine help with anxiety?⌄

Yes, modestly. Several trials show reductions in stress and anxiety with 200 to 400 mg per day. Effects are gentler than prescription medications.

Will theanine make me sleepy?⌄

It promotes calm without true sedation. Many people use it for sleep quality without feeling groggy the next day.

Can I take theanine with coffee?⌄

Yes, this is a popular combination. 100 to 200 mg of each provides smoother focused energy than coffee alone.

How long does theanine take to work?⌄

Effects start within 30 to 60 minutes and last several hours.

Is theanine safe long-term?⌄

Yes, based on the long history of tea consumption and existing trials. There is no evidence of tolerance or dependence.

Track Theanine with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

Coming to App Store

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.