We killed our own angle on L-theanine — here's what the 31 trials actually show
We planned a different article. The intended angle was that "calm" supplements underdose L-theanine relative to the 200 mg used in trials. Then we checked actual product labels — Nature Made Wellblends and Vitafusion both deliver 200 mg per serving. The mainstream category has converged on the studied dose. The claim was false, so we cut it.
What the evidence actually shows turned out to be more useful.
The effect that replicates is focus
Gerolymos 2026 (Mol Psychiatry, PMID 42410082) pooled 31 randomised controlled trials covering 1,168 people. Its clearest finding: a single 200 mg dose, taken 30–60 minutes before cognitive testing, significantly improved choice reaction time — SMD 0.51 (95% CI 0.25–0.77). That's a moderate, well-replicated attention effect, and it's the strongest thing L-theanine has going for it.
The calm is the weaker half
We put the full breakdown — every study, every number, with the PMIDs — on our own site.
Originally published at super-achiever.com. We check viral supplement claims against the primary research and publish the results — including the ones that go against us.