L-Theanine and Cognitive Performance
What human research on L-theanine says about attention, focus and cognitive performance—and why broad memory claims deserve caution.
What L-theanine is
L-theanine is an amino acid associated with tea and is widely marketed for “calm focus.” Human trials have tested attention, reaction time, stress-related outcomes and combinations with caffeine.
The key distinction: acute attention vs lasting memory
Recent systematic-review evidence supports being more confident about selected short-term attention measures than about broad, durable improvements in memory. Results vary by test, dose, timing and whether caffeine is co-administered.
Why 200 mg gets attention
Many acute studies cluster around doses in this neighborhood, which makes MemoryFuel's listed 200 mg amount more interpretable than an undisclosed proprietary blend. Matching a studied dose, however, is not the same thing as proving the finished product works.
Practical reading rule
When a supplement page turns “some evidence for an acute attention measure” into “better memory and mental performance all day,” it has crossed an evidentiary gap. Cognition Current keeps those claims separate.