This site provides general information only and is not medical advice. Talk to a qualified healthcare professional before starting any supplement, especially if you are pregnant, take prescription medication, or have a medical condition.

Some links on this page are affiliate links. If you buy through them, we earn a commission at no extra cost to you. It does not change which products we recommend — see our methodology and full disclosure.

Ingredient

L-Theanine

Promising

An amino acid from green tea associated with a relaxed, alert subjective state.

How it works

Modulates GABA, glutamate, and dopamine signalling and increases alpha-band EEG activity at modest doses.

Evidence

Small RCTs report subjective calm-alertness at 100-200 mg, often paired with caffeine.

Studies

Nobre et al., Asia Pac J Clin Nutr, 2008
Increased alpha-band EEG activity associated with relaxed alertness.
PubMed 18296328 ↗

Top products

Sorted by effective monthly cost

Now Foods L Theanine 200 mg

Now Foods

Per serving: 200 mg
Studied midpointStudied range midpoint is used. Pricing assumes label-recommended servings.See methodology: 250 mg · 2/day

Buy at Amazon.ca

Thorne L Theanine 200 mg

Thorne

Per serving: 200 mg
Studied midpointStudied range midpoint is used. Pricing assumes label-recommended servings.See methodology: 250 mg · 2/day

Buy at Amazon.ca

Momentous L Theanine 100 mg

Momentous

Per serving: 100 mg
Studied midpointStudied range midpoint is used. Pricing assumes label-recommended servings.See methodology: 250 mg · 3/day

Buy at Amazon.ca

Newsletter

One ingredient, one study, one product worth your money.

Weekly. No fluff. Unsubscribe in one click.