Does L-Theanine help cognition? (Grade C evidence)

Explore current source-reported research for this exact question. These records are separate from the synthesis below; they do not update its grade or establish a recommendation.

For cognition, L-Theanine sits at Grade C — a hint of benefit in the recorded evidence, especially in adults, moderate certainty, at doses 100–200 mg.

Exact question reviewed

Population: adults
Intervention: L-Theanine · 100–200 mg
Comparator: not reported
Outcome: cognition
Time horizon: not reported

Bottom line. For cognition, L-Theanine sits at Grade C — a hint of benefit in the recorded evidence, especially in adults, moderate certainty, at doses 100–200 mg. [1 other]

Direction: benefit
Magnitude: improves attention and cuts down distraction, especially paired with caffeine
Grade: C
Certainty: moderate
Clinical meaning: small but potentially useful
Who it applies to: adults
Dose / form studied: 100–200 mg
Safety: not assessed
The one limitation: Claim-specific limitation details are not available in this public record.

Reviewed not reported · Evidence last changed 2026-07-16 · Open evidence record (version 0)

Grade

what does the grade mean?

Certainty

moderate

what does certainty mean?

Grade C / moderate: probably a small effect in specific populations; do not expect a general benefit.

Who it works for

Best-studied in adults. Recorded studied dose: 100–200 mg.

Evidence

Study	Design	Role	Cite
The Cognitive-Enhancing Outcomes of Caffeine and L-theanine: A Systematic Review	peer-reviewed	not classified	PMID:35111479

Why this grade

Reasoning trace

The current record stores Grade C at moderate certainty and links 1 publishable source. A claim-specific domain-by-domain grading rationale is not available in this public record, so no reason for upgrading or downgrading is inferred here.

Audit and version

Claim ID: ec_b1-theanine-cog
Claim version: not reported
Governance: legacy, not verified
Clinician review: Not yet reviewed by a licensed clinician
Last evidence search: not reported
Last editorial review: not verified

Public receipt · Machine-readable claim · Methodology

Dose & form

Studied intake: 100–200 mg.

How it stacks up for cognition

L-Theanine vs Creatine for cognition — Creatine Grade B
L-Theanine vs Caffeine for cognition — Caffeine Grade A
L-Theanine vs Lion's Mane for cognition — Lion's Mane Grade C
L-Theanine vs Ginkgo for cognition — Ginkgo Grade C
L-Theanine vs Iron for cognition — Iron Grade C
L-Theanine vs Ashwagandha for cognition — Ashwagandha Grade C
All interventions graded for cognition →

Grade history

2026-07-16C → CCorrection by Claude (gold-standard provenance sweep): live Postgres source drift replaced with the verified seed source set [pmid-35111479] details →

Re-review cadence: every 6 months (Grade C+) · methodology v1.

Frequently asked

How long does L-Theanine take to work for cognition?

This record does not report a studied onset time for L-Theanine and cognition. Do not assume a typical timeframe.

What dose was used in studies of L-Theanine for cognition?

The recorded studied dose for L-Theanine and cognition is 100–200 mg. This is a source detail, not a dose recommendation.

Does L-Theanine work for cognition if I'm not deficient?

The recorded studied population is adults. This field alone does not show whether deficiency or baseline status changes the effect.

L-Theanine or the next-best alternative for cognition?

See the compare block above for the head-to-head with the most-cited alternative. Grade + certainty differences matter more than any single trial.

What this is — and is not

Evidence description: improves attention and cuts down distraction, especially paired with caffeine
Substrate's interpretation: The current reviewed record assigns Grade C at moderate certainty. A domain-by-domain rationale is shown only when recorded.
Discuss with a clinician: If you're on medication or have a condition that changes the calculus, bring the interaction & population blocks above to your pharmacist or prescriber before deciding.
Individualized medical advice: Not provided here or on any Substrate surface (API, agent tool, embed) — see YMYL policy.

Cite this page

Citation is encouraged. The proposed reuse license is CC-BY-4.0; status: pending-governance-ratification.

Plain-text citation

Substrate. Does L-Theanine help cognition? (Grade C). https://evidencebased.info/interventions/theanine/cognition. Updated 2026-07-16.

BibTeX

@misc{substrate_onstheaninecognition,
  author = {Substrate editorial},
  title  = {Does L-Theanine help cognition?},
  year   = {2026},
  url    = {https://evidencebased.info/interventions/theanine/cognition},
  note   = {Grade C, evidencebased.info}
}

Found something wrong on this page? Report an error →

Current source-reported research

Membership uses admitted intervention and measured-outcome associations for this exact question. Different populations, preparations, comparators and timepoints remain separate. No pooling or update to the synthesis is asserted.