L-theanine smooths caffeine's effects
L-theanine promotes calm focus and reduces caffeine's jittery side effects while preserving alertness benefits.
Classic nootropic stack - take together for focused energy.
Take together; typical ratio is 2:1 theanine:caffeine
L-theanine smooths caffeine's effects. Classic nootropic stack - take together for focused energy.
Take together; typical ratio is 2:1 theanine:caffeine
This interaction is rated “Synergy” by Formulate. L-theanine promotes calm focus and reduces caffeine's jittery side effects while preserving alertness benefits.
Studies from our registry that mention both caffeine and l-theanine. Each links to the primary source and the other Formulate pages citing it.
Both substances · 2008
L-theanine, a natural constituent in tea, and its effect on mental state
Nobre AC, Rao A, Owen GN · Asia Pacific Journal of Clinical Nutrition
Reviews EEG and cognitive evidence that L-theanine increases alpha wave activity (associated with calm alertness) and, when combined with caffeine, improves attention without sedation.
Mentions l-theanine · 2017
Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study
Hidese S, Ogawa S, Ota M, et al. · Acta Neuropsychiatrica
8-week open-label study in major depressive disorder (n=20) found 250mg/day L-theanine improved depression, anxiety, sleep, and cognitive function scores — supporting adjunctive use alongside standard treatment.
Mentions caffeine · 2009
The effects of green tea on weight loss and weight maintenance: a meta-analysis
Hursel R, Viechtbauer W, Westerterp-Plantenga MS · International Journal of Obesity
Meta-analysis of 11 trials found green tea catechins modestly reduced body weight (~1.3kg) over 12 weeks, with effects attenuated in high-caffeine consumers.
Protocol
Best Sleep Supplement Protocol 2026: Clinical Evidence Stack
Build a cheap, non-habit-forming sleep stack using magnesium glycinate, L-theanine, and glycine — three compounds with the strongest clinical trial support.
Guide
Nootropics Guide 2026: Ranked by Clinical Evidence
Learn which nootropics actually work for focus and cognition. Tiered by human RCT data — from caffeine + L-theanine to lion’s mane — with doses, red flags, and stack advice.
Other interactions to know
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Medical disclaimer. This page is for educational purposes only and does not replace advice from a qualified healthcare provider.
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